U.S. patent application number 10/180469 was filed with the patent office on 2003-01-09 for low floor vehicle ramp assembly.
This patent application is currently assigned to Lift-U, Division of Hogan Mfg. Inc.. Invention is credited to Cohn, Alan R., Lewis, Cleatus A., Simon, Curtis J..
Application Number | 20030007853 10/180469 |
Document ID | / |
Family ID | 26740547 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030007853 |
Kind Code |
A1 |
Cohn, Alan R. ; et
al. |
January 9, 2003 |
Low floor vehicle ramp assembly
Abstract
A ramp assembly (20) for mounting in a low floor bus (22) or
other vehicle. The ramp assembly (20) includes a rectangular
enclosure (24) that fits underneath the chassis of the low floor
bus (22). The ramp assembly (20) includes a reciprocating mechanism
(26) for moving a ramp platform (28) between a fully deployed
position and a fully stowed position. During this movement, the
reciprocating mechanism (26) raises the trailing end of the ramp
platform (28) in one translational movement with the extension of
the ramp platform, such that the trailing end of the ramp platform,
when deployed, is raised to the floor level of the low floor bus
(22).
Inventors: |
Cohn, Alan R.; (Lockeford,
CA) ; Lewis, Cleatus A.; (Modesto, CA) ;
Simon, Curtis J.; ( Grove, OK) |
Correspondence
Address: |
CHRISTENSEN, O'CONNOR, JOHNSON, KINDNESS, PLLC
1420 FIFTH AVENUE
SUITE 2800
SEATTLE
WA
98101-2347
US
|
Assignee: |
Lift-U, Division of Hogan Mfg.
Inc.
|
Family ID: |
26740547 |
Appl. No.: |
10/180469 |
Filed: |
June 25, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10180469 |
Jun 25, 2002 |
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09563774 |
May 2, 2000 |
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6409458 |
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09563774 |
May 2, 2000 |
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09164434 |
Sep 30, 1998 |
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09164434 |
Sep 30, 1998 |
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09060948 |
Apr 15, 1998 |
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6186733 |
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Current U.S.
Class: |
414/537 |
Current CPC
Class: |
Y10S 414/134 20130101;
B60R 3/02 20130101; A61G 3/061 20130101; F16H 7/24 20130101; Y10T
74/1884 20150115; B60P 1/431 20130101; A61G 3/067 20161101 |
Class at
Publication: |
414/537 |
International
Class: |
B60P 001/00 |
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A ramp assembly comprising: a frame; a ramp platform mounted in
the frame defining trailing and forward ends and extendible and
retractable along a length of the frame between stowed and deployed
positions, the ramp platform being arranged when deployed such that
the forward end extends down toward the ground; a first locking
mechanism that locks the ramp platform into a fully deployed
position; a second locking mechanism that locks the ramp platform
into a fully stowed position; a reciprocating mechanism for
extending and retracting the ramp platform along a length of the
frame between the stowed and deployed positions; and a time delay
circuit associated with the reciprocating mechanism to delay
actuation of the reciprocating mechanism for a predetermined period
of time.
2. The ramp assembly of claim 1, wherein the first locking
mechanism comprises a first latch plate attached to the frame and a
first latch arm operatively associated with the ramp platform to
extend and retract with the ramp platform and configured and
arranged so as to engage and lock onto the first latch plate when
the ramp platform is in the fully deployed position.
3. The ramp assembly of claim 2, wherein the first latch plate is
adjustable along a longitudinal axis of the frame.
4. The ramp assembly of claim 2, wherein the first locking
mechanism comprises a second latch plate attached to the frame and
a second latch arm operatively associated with the ramp platform to
extend and retract with the ramp platform and configured and
arranged so as to engage and lock onto the second latch plate when
the ramp platform is in the fully deployed position.
5. The ramp assembly of claim 4, wherein the first and second latch
plates are adjustable along a longitudinal axis of the frame.
6. The ramp assembly of claim 4, wherein the second locking
mechanism comprises a stowed latch plate attached to the frame that
is engaged by and locked onto by the second latch arm when the ramp
platform is in the fully stowed position.
7. The ramp assembly of claim 4, further comprising a coupling
linking movement of the first and second latch arms.
8. The ramp assembly of claim 7, further comprising a spring
arranged to bias the first and second latch arms to engage and lock
onto the first and second latch plates, respectively.
9. The ramp assembly of claim 8, further comprising a solenoid
actuator operatively associated with the second latch arm so that
actuation of the solenoid actuator disengages the first and second
latch arms from the first and second latch plates, respectively, in
the fully deployed position, and disengages the second latch arm
from the stowed latch plate in the fully stowed position.
10. The ramp assembly of claim 9, wherein the time delay circuit is
configured to delay the actuation of the reciprocating mechanism
until after actuation of the solenoid actuator, so that the first
and second latch arms are fully disengaged from the first and
second latch plates, respectively, before actuation of the
reciprocating mechanism in the fully deployed position, and so that
the second latch arm is fully disengaged from the stowed latch
plate before actuation of the reciprocating mechanism in the fully
stowed position.
11. The ramp assembly of claim 10, wherein the time delay circuit
is further configured to simultaneously deactuate the solenoid
actuator and actuate the reciprocating mechanism.
12. The ramp assembly of claim 2, wherein the second locking
mechanism comprises a stowed latch plate attached to the frame that
is engaged by and locked onto by the first latch arm when the ramp
platform is in the fully stowed position.
13. The ramp assembly of claim 12, further comprising a spring
arranged to bias the first latch arm to engage and lock onto the
first latch plate.
14. The ramp assembly of claim 13, further comprising a solenoid
actuator operatively associated with the first latch arm so that
actuation of the solenoid actuator disengages the first latch arm
from the first latch plate in the fully deployed position, and
disengages the first latch arm from the stowed latch plate in the
fully stowed position.
15. The ramp assembly of claim 14, wherein the time delay circuit
is configured to delay the actuation of the reciprocating mechanism
until after actuation of the solenoid actuator, so that the first
latch arm is fully disengaged from the first latch plate before
actuation of the reciprocating mechanism in the fully deployed
position, and so that the first latch arm is fully disengaged from
the stowed latch plate before actuation of the reciprocating
mechanism in the fully stowed position.
16. The ramp assembly of claim 15, wherein the time delay circuit
is further configured to simultaneously deactuate the solenoid
actuator and actuate the reciprocating mechanism.
17. The ramp assembly of claim 1, further comprising a single
manual release mechanism, actuation of which (1) releases the first
locking mechanism when the ramp assembly is in the fully deployed
position and (2) releases the second locking mechanism when the
ramp platform is in the fully stowed position.
18. The ramp assembly of claim 17, wherein the first locking
mechanism comprises a first latch plate attached to the frame and a
first latch arm operatively associated with the ramp platform to
extend and retract with the ramp platform and configured and
arranged so as to engage and lock onto the first latch plate when
the ramp platform is in the fully deployed position.
19. The ramp assembly of claim 18, wherein the first latch plate is
adjustable along the longitudinal axis of the frame.
20. The ramp assembly of claim 18, wherein the first locking
mechanism comprises a second latch plate attached to the frame and
a second latch arm operatively associated with the ramp platform to
extend and retract with the ramp platform and configured and
arranged so as to engage and lock onto the second latch plate when
the ramp platform is in the fully deployed position.
21. The ramp assembly of claim 20, wherein the first and second
latch plates are adjustable along a longitudinal axis of the
frame.
22. The ramp assembly of claim 20, wherein the second locking
mechanism comprises a stowed latch plate attached to the frame that
is engaged by and locked onto by the second latch arm when the ramp
platform is in the fully stowed position.
23. The ramp assembly of claim 22, further comprising a coupling
linking movement of the first and second latch arms.
24. The ramp assembly of claim 23, wherein the single manual
release mechanism comprises a handle (1) operatively associated
with the first latch arm when the ramp platform is in the deployed
position such that actuation of the handle causes the first and
second latch arms to release the first and second latch plates, and
(2) operatively associated with the first latch arm when the ramp
platform is in the stowed position such that actuation of the
handle causes the second latch arm to release the stowed latch
plate.
25. The ramp assembly of claim 24, further comprising a spring
arranged to bias the first and second latch arms to engage and lock
onto the first and second latch plates, respectively.
26. The ramp assembly of claim 22, further comprising a solenoid
actuator operatively associated with the second latch arm so that
actuation of the solenoid actuator disengages the first and second
latch arms from the first and second latch plates, respectively, in
the fully deployed position, and disengages the second latch arm
from the stowed latch plate in the fully stowed position.
27. The ramp assembly of claim 2, wherein the second locking
mechanism comprises a stowed latch plate attached to the frame that
is engaged by and locked onto by a second latch arm when the ramp
platform is in the fully stowed position.
28. The ramp assembly of claim 27, wherein the first and second
latch arms each comprise a single latch arm.
29. The ramp assembly of claim 27, further comprising a solenoid
actuator operatively associated with the first and second latch
arms so that actuation of the solenoid actuator disengages the
first latch arm from the first latch plate in the fully deployed
position, and disengages the second latch arm from the stowed latch
plate in the fully stowed position.
30. The ramp assembly of claim 29, wherein the time delay circuit
configured to delay the actuation of the reciprocating mechanism
until after actuation of the solenoid actuator, so that the first
latch arm is fully disengaged from the first latch plate before
actuation of the reciprocating mechanism in the fully deployed
position, and so that the second latch arm is fully disengaged from
the stowed latch plate before actuation of the reciprocating
mechanism in the fully stowed position.
31. The ramp assembly of claim 30, wherein the time delay circuit
is further configured to simultaneously deactuate the solenoid
actuator and actuate the reciprocating mechanism.
32. A ramp assembly comprising: a frame; a ramp platform mounted in
the frame defining trailing and forward ends and extendible and
retractable along a length of the frame between stowed and deployed
positions, the ramp platform being arranged when deployed such that
the forward end extends down toward the ground; a first locking
mechanism actuatable between a locked position, wherein the ramp
platform is locked into a fully deployed position, and an unlocked
position; a release mechanism that unlocks the ramp platform in the
fully deployed position and unlocks the ramp platform in the fully
stowed position; a reciprocating mechanism for extending and
retracting the ramp platform along a length of the frame between
the stowed and deployed positions; and a time delay circuit
associated with the reciprocating mechanism and configured to
selectively delay actuation of the reciprocating mechanism until
the first locking mechanism is in the unlocked position.
33. The ramp assembly of claim 32, wherein the first locking
mechanism comprises a first latch plate attached to the frame and a
first latch arm operatively associated with the ramp platform to
extend and retract with the ramp platform and configured and
arranged so as to engage and lock onto the first latch plate when
the ramp platform is in the fully deployed position.
34. The ramp assembly of claim 33, wherein the first locking
mechanism comprises a second latch plate attached to the frame and
a second latch arm operatively associated with the ramp platform to
extend and retract with the ramp platform and configured and
arranged so as to engage and lock onto the second latch plate when
the ramp platform is in the fully deployed position.
35. The ramp assembly of claim 33, further comprising a second
locking mechanism that locks the ramp platform into a fully stowed
position, wherein the second locking mechanism comprises a stowed
latch plate attached to the frame that is engaged by and locked
onto by a second latch arm when the ramp platform is in the fully
stowed position.
36. The ramp assembly of claim 35, wherein the release mechanism
comprises a cam lever having a camming surface, the camming surface
configured to engage the first latch arm when the ramp platform is
in the fully deployed position so that when the cam lever is
actuated the first latch arm disengages the first latch plate.
37. The ramp assembly of claim 36, further comprising a cable
attached to the cam lever and configured and arranged so as to be
operatively associated with the second latch arm when the ramp
assembly is in the stowed position, and wherein actuation of the
cam lever causes the cable to disengage the second latch arm from
the stowed latch plate.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application of U.S. patent
application Ser. No. 09/563,774, filed May 2, 2000, now U.S. Pat.
No. 6,409,458, issued Jun. 25, 2002, which is a continuation of
U.S. patent application Ser. No. 09/164,434, now abandoned, filed
Sep. 30, 1998, which is a continuation-in-part of U.S. patent
application Ser. No. 09/060,948, filed Apr. 15, 1998, now U.S. Pat.
No. 6,186,733, issued Feb. 13, 2001, all of which are hereby
expressly incorporated by reference.
TECHNICAL FIELD OF THE INVENTION
[0002] This invention relates generally to retractable ramp
platforms that facilitate boarding of a passenger onto a vehicle
and, in particular, retractable ramp platforms that facilitate
access to a low floor vehicle.
BACKGROUND OF THE INVENTION
[0003] Intra-city buses have included wheelchair lifts for
transporting persons of limited mobility in and out of the
vehicles. Typically, a prior art wheelchair lift included a
mechanically driven platform to raise and lower a passenger between
loading from outside of the vehicle at ground level and entry into
the vehicle at a vehicle floor level. For example, wheelchair lifts
of the type installed in the stairwell of transit vehicles, such as
intra-city buses, have been used for some time. One type of prior
art wheelchair lift, commonly referred to as a "step lift" was
disclosed in U.S. Pat. No. 4,466,771 to Thorley et al. The step
lift in Thorley et al. was designed to be installed in the
stairwell of a transit vehicle, and included hinged panels that
were movable between a step configuration and a platform
configuration. In the step configuration, the hinged panels formed
steps for use by passengers to board and exit the vehicle. In the
platform configuration, the hinged panels formed a horizontal
platform used to raise and lower a wheelchair passenger between a
vehicle floor-level position and a ground-level position.
[0004] Municipalities recently began using "low floor buses." In
this style of bus, a passenger entered the bus at a level that was
above ground by a sufficient amount so that the chassis had proper
ground clearance. The floor of the bus throughout the vehicle was
substantially at this level. It was believed that such buses were
more stable in operation, and permitted simpler egress and ingress
of passengers.
[0005] A problem encountered with the low floor buses was that
wheelchair lifts such as were disclosed in Thorley et al. could not
be installed in the buses because there was not a stairwell.
Moreover, the low floor buses lacked sufficient underchassis space
to mount the complex lifting mechanisms for a wheelchair lift.
Therefore, other systems had to be developed to accommodate
wheelchair users and other passengers of limited mobility. To
address these concerns, some manufacturers developed ramp
assemblies for providing limited mobility passengers access into
and out of the low floor buses. The ramp assemblies were structures
that selectively provided a ramp platform that extended between the
outside ground and the floor of a vehicle such as an intra-city bus
to provide access into and out of the vehicle.
[0006] Prior art ramp assemblies typically stowed the ramp platform
under the vehicles when not in use, and deployed the ramp platform
when it was necessary to provide passenger access. When the ramp
platform was deployed, the two ends were positioned at different
heights, creating a slope upward from the ground to the bus floor.
An example of a ramp assembly for use in a low floor bus was
disclosed in U.S. Pat. No. 5,636,399 to Tremblay et al. A similar
ramp assembly for use in a van was disclosed in U.S. Pat. No.
5,393,192 to Hall et al.
[0007] One of the problems found in designing prior art ramp
assemblies for low floor vehicles was the limited amount of space
allotted for the ramp platform and its reciprocating mechanism,
including the motor and necessary drive mechanism. Because the low
floor buses lacked a stairwell and a raised floor under which the
ramp assembly could be mounted, the designer was forced to minimize
size in all dimensions to prevent loss of ground clearance or
interference with other underchassis structures. Tremblay et al.
and Hall et al. addressed this problem by providing a compact ramp
assembly. However, while the ramp assemblies disclosed in Tremblay
et al. and Hall et al. were relatively small, the motors used for
the ramps were mounted behind or underneath the frame for the ramp
assembly, requiring additional installation area underneath the
vehicle. There exists a need for a more efficient manner of
mounting a motor for a ramp assembly.
[0008] Another problem with the prior art ramp assemblies was that
the ramp platform was stowed several inches below the floor level
and, to reach the deployed position, had to be raised to extend
between the floor and the ground. Alternatively, some form of
transition between the ramp in the deployed position and the floor
had to be provided. Tremblay et al. addressed this problem by
providing a hinged panel that formed a transition between the floor
and the ramp platform. Hall et al., on the other hand, provided a
complex tilting mechanism utilizing a reciprocating motor to lift
the trailing end of the ramp to floor level. There is a need for a
less complex mechanism for providing a transition between the floor
and a ramp platform.
[0009] Another problem with prior art ramp assemblies is that, if
power was cut to the reciprocating mechanism for the ramp platform,
the ramp platform may be stuck in a deployed position. In such
case, the driver of the bus would have to wait for maintenance
crews to repair, or at least stow, the ramp platform. There is a
need for a more simple way of retracting a ramp platform when the
reciprocating mechanism for the ramp platform is inoperable.
SUMMARY OF THE INVENTION
[0010] In accordance with one embodiment of the invention, the ramp
assembly includes a frame for mounting below a floor of a vehicle
and a ramp platform mounted in the frame. The ramp assembly also
includes a first locking mechanism that locks the ramp platform
into a fully deployed position, and a second locking mechanism that
locks the ramp platform into a fully stowed position. A
reciprocating mechanism is provided for extending and retracting
the ramp platform along a length of the frame between the stowed
and deployed positions. The ramp assembly also includes a time
delay circuit associated with the reciprocating mechanism to delay
actuation of the reciprocating mechanism for a predetermined period
of time.
[0011] The first locking mechanism preferably includes a first
latch arm operatively associated with the reciprocating mechanism
to extend and retract with the ramp platform and a first latch
plate attached to the frame that is engaged by the first latch arm
when the ramp platform is in the fully deployed position. A second
latch arm can be operatively associated with the reciprocating
mechanism to extend and retract with the ramp platform that engages
a second latch plate attached to the frame when the ramp platform
is in the fully deployed position.
[0012] In accordance with other aspects of one embodiment of the
present invention, the ramp assembly also includes a release
mechanism. The single manual release mechanism preferably includes
a handle (1) operatively associated with the first latch arm when
the ramp platform is in the deployed position such that actuation
of the handle causes both the first and second latch arms to
release the first and second latch plates, and (2) operatively
associated with the second latch arm when the ramp platform is in
the stowed position such that actuation of the handle causes the
second latch arm to release the third latch plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing aspects and many of the attendant advantages
of this invention will become better understood by reference to the
following detailed description, when taken in conjunction with the
accompanying drawings, wherein:
[0014] FIG. 1 is a partial side view of a low floor bus having a
ramp assembly made in accordance with the present invention;
[0015] FIG. 2 is a front isometric view of the ramp assembly in
FIG. 1, with the ramp assembly removed from the low floor bus, the
ramp platform fully deployed, and the top panel removed for
detail;
[0016] FIG. 3 is a front isometric view of the ramp assembly in
FIG. 2, with the ramp platform fully stowed;
[0017] FIG. 4 is a rear isometric view of the ramp assembly in FIG.
2;
[0018] FIG. 5 is a top plan view of the ramp assembly in FIG.
2;
[0019] FIG. 6 is a sectional view of the rectangular enclosure for
the ramp assembly in FIG. 1, taken along the sectional lines 6-6 in
FIG. 5, with the rectangular motor plate and the ramp platform
removed for detail;
[0020] FIG. 7 is a partial sectional view taken along the sectional
lines 7-7 in FIG. 5;
[0021] FIG. 8 is a partial sectional view taken along the section
lines 6-6 in FIG. 5, with the rectangular motor plate and the ramp
platform in position;
[0022] FIG. 9 is a sectional view similar to FIG. 6, with the
rectangular motor plate and the ramp platform in position, and the
ramp platform fully stowed;
[0023] FIG. 10 is a partial sectional view similar to FIG. 8, with
the ramp platform 14 inches retracted;
[0024] FIG. 11 is a partial sectional view similar to FIG. 8, with
the ramp platform 11 inches retracted;
[0025] FIG. 12 is a partial sectional view similar to FIG. 8, with
the ramp platform 9 inches retracted;
[0026] FIG. 13 is a partial sectional view similar to FIG. 8, with
the ramp platform 6 inches retracted;
[0027] FIG. 14 is a partial sectional view similar to FIG. 8, with
the ramp platform 4 inches retracted;
[0028] FIG. 15 is a partial sectional view similar to FIG. 8, with
the ramp platform 11/4 inch retracted;
[0029] FIG. 16 is a partial sectional view similar to FIG. 8, with
the ramp platform {fraction (3/4)} inch retracted;
[0030] FIG. 17 is a partial sectional view similar to FIG. 8, with
the ramp platform {fraction (1/2)} inch retracted;
[0031] FIG. 18 is a partial sectional view similar to FIG. 8, with
the ramp platform {fraction (1/4)} inch retracted;
[0032] FIG. 19 is a top plan view of the ramp assembly in FIG. 2,
showing the latching mechanism of the present invention, with the
rectangular motor plate and the ramp platform removed for detail,
and the ramp assembly in the deployed position;
[0033] FIG. 20 is a detail view of the first latch plate of the
latching mechanism in FIG. 19, with the latch pivot arms and the
coupling arm removed for detail;
[0034] FIG. 21 is a detail view of the first latch plate in FIG.
20, with the latch arm manually actuated;
[0035] FIG. 22 is a detail view of the second latch plate of the
latching mechanism in FIG. 19 with the latch pivot arms and the
coupling arm removed for detail;
[0036] FIG. 23 is a detail view of the second latch plate in FIG.
20, with the latch arm manually actuated;
[0037] FIG. 24 is a top plan view similar to FIG. 19, with the ramp
assembly in the stowed position;
[0038] FIG. 25 is a detail view of the first latch arm in FIG.
24;
[0039] FIG. 26 is a detail view of the first latch arm in FIG. 25,
with the latch arm manually actuated;
[0040] FIG. 27 is a detail view of the second latch arm in FIG.
24;
[0041] FIG. 28 is a detail view of the second latch arm in FIG. 25,
with the latch arm manually actuated;
[0042] FIG. 29 is a rear, top perspective view of a second
embodiment of a ramp assembly made in accordance with the present
invention, with the ramp platform in the deployed position;
[0043] FIG. 30 is a front, top perspective view of the ramp
assembly in FIG. 29, with the ramp platform in the stowed
position;
[0044] FIG. 31 is a top cutaway view of the rectangular motor plate
for the ramp assembly in FIG. 29;
[0045] FIG. 32 is a side cutaway view of the lever arm of the ramp
assembly in FIG. 29, with the ramp platform deployed a distance
that is substantially the same as the deployment of the ramp
platform in FIG. 15;
[0046] FIG. 33 is an exploded perspective view of the attachment of
the lever arm in FIG. 32 to the ramp platform;
[0047] FIG. 34 is an operation diagram for a delay circuit for the
solenoids and motor of the ramp assembly in FIG. 29;
[0048] FIG. 35 is a bottom cutaway view of an adjustable deployed
latch plate for the ramp assembly in FIG. 29;
[0049] FIG. 36 is a bottom view of the adjustable deployed latch
plate in FIG. 35, with the bottom plate removed, and a latch arm
shown in position against the latch plate;
[0050] FIG. 37 is a rear, underside view of a belt release
mechanism for the ramp assembly in FIG. 29;
[0051] FIG. 38 is the belt release mechanism in FIG. 37, with the
rectangular enclosure for the ramp assembly removed for detail;
[0052] FIG. 39 is a side perspective view of the belt release
assembly for the belt release mechanism in FIG. 38;
[0053] FIG. 40 is a front, top perspective view of the ramp
assembly in FIG. 29, with the belt release mechanism released so
that the tension in the belt is removed;
[0054] FIG. 41 is a detailed cutaway view of the handles for the
belt release mechanism and manual unlatching mechanism of the ramp
assembly in FIG. 29, with the handle for the belt release mechanism
turned to a locked position;
[0055] FIG. 42 is the belt release mechanism in FIG. 38, with the
belt released;
[0056] FIG. 43 is the belt release assembly in FIG. 39, with the
belt release mechanism in the position shown in FIG. 42;
[0057] FIG. 44 is a side perspective view of a drive belt clutch
mechanism in the ramp assembly in FIG. 29;
[0058] FIG. 45 is a side perspective view of a clutch saddle in the
drive belt clutch mechanism in FIG. 44;
[0059] FIG. 46 is a side cutaway view showing the drive belt
extending through the drive belt clutch mechanism in FIG. 44, with
the drive belt tensioned;
[0060] FIG. 47 is the cutaway view in FIG. 46, with the drive belt
released;
[0061] FIG. 48 is a side perspective view of an adjustable clamp
for a belt tensioner in the ramp assembly in FIG. 29;
[0062] FIG. 49 is a stationary plate used with the adjustable clamp
in FIG. 48 in formation of the belt tensioner for the ramp assembly
in FIG. 29;
[0063] FIG. 50 is a release tool for use with the ramp assembly in
FIG. 29;
[0064] FIG. 51 is a rear, bottom perspective view of the ramp
assembly in FIG. 29;
[0065] FIG. 52 is a side cutaway view of the belt tensioner for the
ramp assembly in FIG. 29, the parts of which are shown in FIGS. 40
and 49; and
[0066] FIG. 53 is a side perspective view of a wire rope retainer
for the pulleys in the ramp assembly in FIG. 29.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0067] Referring now to the drawing, in which like reference
numerals represent like parts throughout the several views, FIG. 2
shows a ramp assembly 20 for mounting in a low floor bus 22 (FIG.
1) or other vehicle. The ramp assembly 20 fits within a frame, in
the drawings shown as a rectangular enclosure 24, that fits
underneath the chassis of the low floor bus 22. The ramp assembly
20 includes a reciprocating mechanism 26 for moving a ramp platform
28 between a fully deployed position (FIG. 2) and a fully stowed
position (FIG. 3).
[0068] The rectangular enclosure 24 includes side panels 32, 34, an
end panel 36, a bottom panel 38 and a removable top panel 40 (shown
removed from and raised above the rectangular enclosure 24 in FIG.
3). The side panels 32, 34, the end panel 36, and the bottom panel
38 are a weldment that provides a structural frame to house the
ramp platform 28 and the reciprocating mechanism 26 along the plane
of the rectangular enclosure 24. Preferably, the side panels 32, 34
include bottom flanges (not shown) that provide structural support
for the bottom panel 38. The top panel 40 functions as a cover for
the rectangular enclosure 24 and, as described above, is removable.
The rectangular enclosure 24 is attached below the doorway of the
low floor bus 22 by brackets 41, welding or another method known in
the art. When in place, the top panel 40 is located just below the
floor of the doorway of the low floor bus 22 (FIG. 1).
[0069] A hinged closure panel 42 (FIG. 3) is attached to the
forward end of the rectangular enclosure 24 (opposite the end panel
36). The hinged closure panel 42 is hinged from the bottom panel 38
and is spring-loaded to the closed position. The hinged closure
panel 42 includes V-shaped brackets 44 (FIG. 8) on its inner side,
adjacent to the side panels 32, 34, and arranged so that the point
of the V extends toward the end panel 36 when the hinged closure
panel 42 is closed. As is described in detail below, the V-shaped
brackets 44 are contacted by the ramp platform 28 at the beginning
of deployment of the ramp platform so as to open the hinged closure
panel 42.
[0070] FIG. 6 shows a side view of the inside of one of the side
panels 34. The side panel 34 includes a guide bar 46 extending
along an upper surface thereof. The outboard, or forward end of the
guide bar 46 has a serpentine profile. Specifically, the guide bar
46 extends upward at a rear juncture 48 and continues upward to a
peak 50 where the guide bar turns and extends downward to a forward
juncture 52. Just forward of the forward juncture 52, the guide bar
46 tapers upward at a sloped front edge 53.
[0071] The outer edges of the bottom panel 38 include bottom flange
support bearings 54 directly below the guide bars 46. The bottom
flange support bearings 54 can rest on top of bottom flanges for
the side panels 32, 34, if provided. The bottom flange support
bearings 54 extend along the bottom panel 38 adjacent to the side
panel 34 and underneath the guide bars 46, and are preferably
manufactured from a low friction material such as Nylatron.TM.
bearing material. The bearing material does not require
lubrication, which improves reliability and reduces maintenance.
The bottom flange support bearings 54 are preferably the same
height along their lengths, with the exception of a tapered leading
edge 55 (FIG. 6).
[0072] Cap screw heads, or pins 56 (FIG. 6), extend into the side
panels 32, 34, and are located at the forward end of the
rectangular enclosure 24 just above the forward juncture 52 of the
guide bars 46. As described in detail below, the pins 56 act as
abutment surfaces for rotating the trailing end of the ramp
platform upward at the end of deployment of the ramp platform.
[0073] An upper cross-member 58 spans the width of the forward end
of the rectangular enclosure 24. The upper cross-member 58 provides
additional structural support for the rectangular enclosure 24, as
well as threshold support for passenger foot traffic at the edge of
the doorway for the low floor bus 22.
[0074] A structural channel 60 (FIG. 2) is located above the
reciprocating mechanism 26 and the ramp platform 28, and is fixed
between the rearward portion of the rectangular enclosure 24
(adjacent to the end panel 36) and the upper cross-member 58. The
structural channel 60 provides longitudinal structure for the
rectangular enclosure 24, as well as support for components of the
reciprocating mechanism 26, as is described in detail below.
[0075] The reciprocating mechanism 26 includes a rectangular motor
plate 62 having bearing strips 64 attached at its ends. The
rectangular motor plate 62 is of sufficient length so as to rest on
top of and run along the bottom flange support bearings 54 on
opposite sides of the bottom panel 38. The bearing strips 64 are of
sufficient height and shape to fit snugly between the guide bars
46, the rectangular motor plate 62, and the bottom flange support
bearings 54. The bearing strips 64 are preferably manufactured from
a low-friction material so that they freely slide along the top of
the bottom flange support bearings 54 and bottom surface of the
guide bars 46.
[0076] An electric motor 72 is attached to a motor mount 77, which
is mounted on the rectangular motor plate 62 such that the motor
extends lengthwise on the motor plate and such that a motor shaft
(not shown) extending out of the electrical motor also extends
lengthwise. A flexible coupling 74b connects the motor shaft to a
drive shaft 74a (FIG. 5). Although the electric motor 72 is
disclosed as being electric, it is to be understood that hydraulic,
pneumatic, or other powered motors could be used. A drive pulley 76
(FIG. 7) is located on the drive shaft 74a. The drive shaft 74a is
supported by bearings (not shown) pressed into a mounting plate 73
(FIG. 7) that is attached to the rectangular motor plate 62.
[0077] A pair of idler pulleys 78 (FIG. 7) are mounted on opposite
sides of the drive pulley 76. The central axes of the idler pulleys
78 extend parallel to the central axis of the drive pulley 76. The
idler pulleys 78 roll on stationary idler shafts 78a, using
bearings (not shown).
[0078] A drive belt 80 is fixed at both ends to opposite ends of
the rectangular enclosure 24. The drive belt 80 includes ribs or
holes (not shown) that are engaged by teeth 81 on the drive pulley
76 (FIG. 7). The drive belt 80 extends over both of the idler
pulleys 78 and under the drive pulley 76, ensuring proper
engagement of the drive belt 80 with the drive pulley 76. The
forward end of the drive belt 80 is attached by a drive belt clamp
79 that is adjustable to tension the drive belt 80. The structural
channel 60 provides support for the drive belt clamp 79, and serves
as a cover for the drive belt 80.
[0079] A torque shaft 82 (FIG. 3) extends along the forward edge of
the rectangular motor plate 62 and is mounted for rotation in bores
64a in the forward end of the bearing strips 64. Lever arms 84
(FIG. 8) are mounted on opposite ends of the torque shaft 82 for
rotation with the torque shaft. Each of the lever arms 84 is shaped
like an elongate triangle with rounded edges. The pointed distal
end of the elongate triangle faces forward, and the bottom opposite
corner of the triangle is attached for rotation on the torque shaft
82. A curved slot 86 is located on the third corner of the triangle
and faces upward. The triangular shape of the lever arm 84 causes
the mouth of the curved slot 86 to face somewhat forward as well as
upward. The pointed, forward end of each of the lever arms 84 is
pivotally attached to trunnions 87 that are fixed to the sides of
the ramp platform 28 near its rearward end (FIG. 4).
[0080] Each of the trunnions 87 includes a circular bearing 88
mounted thereon and attached to the associated lever arm 84. The
circular bearing 88 functions as a cam follower located between and
influenced by the guide bars 46 and the bottom bearing flange
support 54.
[0081] A coiled electrical cable 90 (FIGS. 3 and 5 only) supplies
power to the electrical motor 72 and other electrical components on
the rectangular motor plate 62. The coiled electrical cable 90
wraps around a rod 92 that extends the length of the upper portion
of the rectangular enclosure 24. The coiled electrical cable 90 is
configured much like an extension spring, such that as the
rectangular motor plate 62 travels back and forth through its range
of motion, the coiled electrical cable compresses in the stowed
position (FIG. 3), and stretches the length of the rectangular
enclosure 24 in the deployed position (FIG. 5). During this
extension and retraction, the coiled electrical cable 90 is
supported and guided by the rod 92, which prevents the coiled
electrical cable from becoming entangled in the reciprocating
mechanism 26. If different types of motors are used, power (such as
hydraulic fluid) can be supplied by a similar coiled supply
line.
[0082] The ramp platform 28 is rectangular in shape and is of
sufficient width to accommodate persons in wheelchairs and/or
mobility aid devices. To minimize weight, the ramp platform 28 is
preferably constructed of thin sheet metal having a corrugated
sheet 102 (FIG. 10) extending between upper and lower sheets 104,
106. Alternatively, the ramp platform can be made of lightweight
aluminum or a composite material of sufficient strength and
stiffness to support the weight of passengers boarding the ramp
platform 28. A non-skid material or other covering (not shown) can
be used- on the top surface of the ramp platform 28 to aid a
passenger in loading the vehicle.
[0083] Stationary side curbs 108 extend along the outer edges of
the ramp platform 28. The stationary side curbs 108 are preferably
at least two inches in height, thereby preventing a wheelchair or a
mobility aid device from rolling off of the sides of the ramp
platform 28. The rearward, or inboard ends of the stationary side
curbs 108 include bevels 110, which permit deployment of the ramp
platform 28 without interference with the enclosure 24.
[0084] The ramp platform 28 includes a beveled leading edge 114
extending along the width of its forward end. The beveled leading
edge 114 contacts the ground when the ramp platform 28 is fully
deployed so as to provide a minimum threshold height when the
wheels of a wheelchair roll onto the ramp platform.
[0085] Bearing blocks 116 are attached to the leading outside edges
of the stationary side curbs 108. The bearing blocks 116 extend
between the guide bars 46 and the bottom flange support bearings 54
when the ramp platform 28 is withdrawn to the stowed position. The
bearing blocks 116 prevent the ramp platform 28 from rattling or
bouncing within the enclosure as the vehicle travels down
roadways.
[0086] A latch mechanism 120 (FIGS. 19-28) is used to selectively
hold the ramp platform 28 in the deployed or stowed positions. The
latch mechanism 120 includes first and second latch arms 122, 124
(best shown in FIGS. 20 AND 22) extending underneath the
rectangular motor plate 62 and pivotally mounted about their
centers on pins 126, 128. The pins 126, 128 extend through
orthogonal bores (not shown) in the left central and right central
halves of the rectangular motor plate 62, respectively. Thus, the
first and second latch arms 122, 124 travel with the rectangular
motor plate 62 during extension and retraction of the ramp platform
28.
[0087] The first latch arm 122 includes a cutout 130 on the front,
right end of the latch arm. The cutout 130 is spaced from the pin
126. The second latch arm 124 includes two cutouts 132, 134 located
on opposite sides and on opposite ends of the second latch arm.
Both of these cutouts 132, 134 are spaced from the pin 128.
[0088] Movement of the two latch arms 122, 124 is tied by a
coupling arm 136, a short pivot arm 138, and a long pivot arm 140.
The short pivot arm 138 is attached for rotation with the first
latch arm 122 by the pin 126, and extends above the rectangular
motor plate 62 parallel with the rearward portion of the first
lever arm 122. The long pivot arm 140 is fixed for rotation with
the second latch arm 124 by the pivot pin 128, and extends above
the rectangular motor plate 62 parallel with the second latch arm
124. The coupling arm 136 is rotatably attached to the distal,
rearward ends of the short pivot arm 138 and long pivot arm 140.
The opposite end of the long pivot arm 140 is attached to the apex
of a triangular plate 142. The base of the triangular plate 142 is
attached to the actuating arms on a pair of solenoids 144.
[0089] Actuation of the solenoids 144 causes the long pivot arm 140
to rotate, which through the coupling arm 136 causes the short
pivot arm 138 to rotate. Because the short pivot arm 138 is fixed
for rotation with the latch arm 122, and the long pivot arm 140 is
fixed for rotation with the latch arm 124, rotation of the short
and long pivot arms 138, 140 causes a corresponding rotation of the
latch arms 122, 124.
[0090] The cutout 130 in the latch arm 122 and the cutout 132 in
the latch arm 124 are configured so as to extend over protrusions
on deployed latch plates 146, 148 located at the forward end of the
bottom panel 38. The deployed latch plates 146, 148 lie below the
path of the rectangular motor plate 62 and the ramp platform
28.
[0091] When the ramp platform 28 is fully deployed, the cutouts
130, 132 extend over the deployed latch plates 146, 148 (FIGS. 20
AND 22), preventing movement of the rectangular motor plate 62 and
the ramp platform 28. In this manner, the latch mechanism 120 acts
as a dual locking mechanism to hold the rectangular motor plate 62
and the ramp platform 28 in the deployed position. A spring 150 is
attached to the rearward, distal end of the long pivot arm 140, and
biases the latch arms 122, 124 toward counterclockwise rotation so
that cutouts 130, 132 maintain locking engagement with the deployed
latch plates 146, 148. To overcome this locking engagement, the
solenoids 144 are actuated, causing the triangular plate 142 to
retract and rotate the latch arms 122, 124 in the clockwise
direction, thereby releasing the deployed latch plates 146, 148
from the cutouts 130, 132 (FIGS. 21 and 23).
[0092] The latch arms 122, 124 include rounded front ends having
tapered leading sections 152, 154. The tapered leading sections
152, 154 cause the latch arms 122, 124 to engage and roll over the
deployed latch plates 146, 148 as the rectangular motor plate 62
and the ramp platform 28 are extended to the deployed position. The
tapered leading sections 152, 154 continue to rotate the latch arms
122, 124 until the cutouts 130, 132 snap into place onto the
deployed latch plates 146, 148 when the ramp platform 28 is fully
deployed.
[0093] The cutout 134 on the rearward end of the latch arm 124 is
configured to fit over a stowed latch plate 156 at the rearward
portion of the rectangular enclosure 24. The stowed latch plate 156
is located on the bottom panel 38, and is sized so as to fit under
the rectangular motor plate 62 when the ramp platform 28 is stowed.
The rearward edge of the second latch arm 124 includes a tapered
trailing section 158 designed to engage and roll over the latch
plate 156 during retraction of the ramp platform 28. Thus, the
engagement of the cutout 134 with the stowed latch plate 156 acts
as a locking mechanism to hold the ramp platform 28 and rectangular
motor plate 62 in position when the ramp platform is in the stowed
position.
[0094] In use, the low floor bus 22 reaches a destination and the
ramp platform 28 is deployed. During travel, the ramp platform 28
is maintained in the stowed position (FIG. 9), and is held in place
by the contact of the cutout 134 of the second latch arm 124 on the
stowed latch plate 156. To deploy the ramp platform 28, the driver
of the low floor bus 22 presses a deploy switch (not shown), which
actuates the solenoids 144, releasing the cutout 134 from the
stowed latch plate 156. Then, the electric motor 72 is powered
causing the drive pulley 76 to rotate. Rotation of the drive pulley
76 causes the drive pulley 76 to move along the drive belt 80,
advancing the rectangular motor plate 62 and the ramp platform 28
within the rectangular enclosure 24. At the beginning of this
movement, the leading end of the ramp platform 28 engages the
V-shaped bracket 44 on the hinged closure panel 42, causing the
hinged closure panel to swing downward and expose the inside of the
rectangular enclosure 24. During the beginning of extension of the
ramp platform 28 and the rectangular motor plate 62, the bearing
blocks 116 move along and between the guide bars 46 and the bottom
flange support bearings 54. The bearing blocks 116 extend beyond
the end of the guide bars 46 and the bottom flange support bearings
54 after a short extension of the ramp platform 28.
[0095] During extension of the ramp platform 28 and the rectangular
motor plate 62, the bearing strips 64 on the outer edges of the
rectangular motor plate are guided below the lower surface of guide
bars 46, and ride along the upper surface of the bottom flange
support bearings 54. In addition, the outer edges of the
rectangular motor plate 62 and the outer side edges of the ramp
platform 28 ride along the upper surface of the bottom flange
support bearings 54. The circular bearings 88 are trapped between
the bottom flange support bearings 54 and the guide bars 46 during
this extension.
[0096] As the ramp platform 28 extends outward and more than half
of the ramp platform extends out of the rectangular enclosure 24,
the weight of the forward end of the ramp platform cantilevers the
rearward end of the ramp platform upward around the tapered leading
edge 55 of the bottom flange support bearings 54, pressing the
circular bearing 88 upward against the lower surface of the guide
bars 46. The serpentine profile of the lower edge of the guide bars
46 causes the circular bearings 88 to act as cam followers that
engage and are influenced by the serpentine profile to control the
ramp platform's angle with respect to the rectangular enclosure
24.
[0097] As the circular bearings 88 reach the rear junctures 48 of
the guide bars 46 (FIG. 10), the circular bearings begin an upward
climb toward the peak 50 of the guide bars. The torque shaft 82,
however, remains adjacent to the bottom flange support bearings 54
because the torque shaft is attached to the bearing strips 64,
which are confined from movement upward by the lower surface of the
guide bars 46. Thus, the lever arms 84 rotate about the torque
shaft 82 so that the curved slots 86 extend almost straight upward
relative to the rectangular motor plate 62 (FIG. 11).
[0098] After the circular bearings 88 have reached the peaks 50
(FIG. 12), the circular bearings begin a downward motion (FIG. 13)
toward the forward junctures 52 (FIG. 14). When the circular
bearings 88 reach the peaks 50, the angle of the ramp platform 28
with the bottom panel 38 is the same as the angle of the section of
the guide bars 46 between the peak 50 and forward juncture 52 with
the bottom panel. Thus, as the circular bearings 88 move downward
toward the forward junctures 52, the ramp platform 28 extends in a
linear manner along an angle which is equal to the lower surface of
the guide bars 46.
[0099] As the ramp platform 28 approaches the last few inches of
the deployment, the circular bearings 88 extend beyond the ends of
the guide bars 46 and the bottom flange support bearings 54 (FIG.
15). By this time, the beveled leading edge 114 of the ramp
platform 28 is resting on the ground. After a little more
advancement of the ramp platform 28, the curved slots 86 on each of
the lever arms 84 engage the pins 56 (FIG. 16). The pins 56 act as
abutment surfaces for engaging and rotating the lever arms 84. The
engagement of the curved slots 86 with the pins 56 stops
advancement of the top portions of the lever arms 84, causing the
lever arms to rotate about the torque shaft 82. As is shown
sequentially in FIGS. 17, 18, and 8, the lever arms 84 continue to
rotate, lifting the trailing end of the ramp platform 28 upward
until the trailing end of the ramp platform is aligned with the
upper cross-member 58.
[0100] During the final advancement of the ramp platform 28, the
lever arms 84 contact the V-shaped brackets 44 on the hinged
closure panel 42, causing the hinged closure panel to pivot
downward clear of the underside of the deployed ramp platform 28.
In addition, the leading edges of the bearing strips 64 are
captured between the forward juncture 52 of the guide bars 46 and
the bottom flange support bearings 54. This capturing adds
stability to the fully-deployed ramp platform 28. When the ramp
platform is fully deployed, the latch arms 122, 124 lock onto the
deployed latch plates 146, 148.
[0101] The curved slots 86 are toleranced to influence control of
the pivot of the lever arms 84 during travel. Specifically, the
curved slots 86 and the lever arms 84 are arranged so that the
trailing end of the ramp platform 28 moves substantially straight
upward and downward after the bearings 88 have extended beyond the
end of the guide bars. During this movement, concave rear surfaces
152 of the curved slots 86 move along the pins 56. This movement
helps in retracting the ramp platform 28, because it forces the
lever arms 84 to pivot downward and not rely on gravity. The torque
shaft 82 provides continuity from one lever arm 84 to the other
should non-uniform loads be applied to the ramp platform 28.
[0102] As can be best seen in FIG. 6, the serpentine profile of the
guide rail 46 and the substantially straight configuration of the
bottom flange support bearings 54 creates a gap 154 between the
guide rail and the bottom flange support bearings underneath the
peak 50. The gap 154 permits free movement of the circular bearings
88 between the guide rail 46 and the bottom flange support bearings
54 so that the ramp platform 28 can extend at a variety of
different angles relative to the rectangular enclosure 24. This
freedom of movement of the circular bearings 88 permits the ramp
platform 28 to extend in a variety of different angles relative to
the rectangular enclosure 24, allowing the ramp platform 28 to be
deployed onto surfaces having varying heights. If the leading end
of the ramp platform 28 comes into contact with the ground, the
weight of the ramp platform no longer cantilevers the circular
bearings 88 into contact with the guide rail 46. Instead, the
circular bearings 88 lower toward the bottom flange support
bearings 54 and the ramp platform 28 continues to extend, with the
leading edge of the ramp platform dragging on the ground, until the
ramp platform is fully extended. In this manner, the ramp platform
28 can be deployed onto different surfaces having varying
heights.
[0103] As is best shown in FIG. 5, a limit switch 160 is located on
the rectangular motor plate between the solenoids 144 and the
electrical motor 72. The limit switch 160 includes an arm 162 that
engages a first stop 164 (near the upper cross member 58, FIG. 3)
upon full deployment of the ramp platform 28, and a second stop 166
(adjacent the end panel 36, FIG. 4) upon full retraction of the
ramp platform 28. The limit switch 160 signals the control logic
system for the ramp assembly 20 that the ramp platform is in the
fully stowed or fully deployed positions. Once the ramp platform 28
is in either position, power is disconnected from the electrical
motor 72.
[0104] To retract the ramp platform 28, the driver actuates a
"stow" button (not shown), which causes the solenoids 144 to
actuate and release the latch arms 122, 124 from the deployed latch
plates 146, 148. Then, the electric motor 72 is powered causing the
drive pulley 76 to rotate. Rotation of the drive pulley 76 causes
the drive pulley to move along the drive belt 80, causing the
rectangular motor plate 62 to move backward, rotating the lever
arms 84, and thereby lowering the rearward end of the ramp platform
28. As described above, the front edge of the guide bars 46 include
a sloped front edge 53 so as to direct the circular bearings 88 to
between the guide bar and the bottom flange support bearing 54. The
tapered leading edge 55 of the bottom flange support bearings 54
also helps to guide the circular bearings 88 into the cam slots
formed by the guide bars 46 and the bottom flange support bearings
54.
[0105] Once the pins 56 are released from the curved slots 86 of
the lever arms 84, the lever arms 84 cease rotation, and the ramp
platform 28 begins retraction. As the ramp platform 28 is
retracted, the circular bearings 88 once again engage the lower
surfaces of the guide bars 46, and move along the serpentine path
of the guide bars until at least half of the ramp platform 28 is
within the rectangular enclosure 24, and the weight of the ramp
platform is upon the bottom flange support bearings 54. During this
movement, the rectangular motor plate 62 continues to retract and
pull the ramp platform 28 toward the rear portion of the
rectangular enclosure 24. The latch arm 124 eventually engages and
rolls over the stowed latch plate 156, and locks in place. The
limit switch 160 is engaged by the stop 166, and power is cut to
the electrical motor 72. At the end of the retraction of the ramp
platform 28, the hinged closure panel 42 closes. The stowed ramp
platform 28 is now ready for travel.
[0106] On occasions when electrical power to the ramp assembly 20
should fail, a manual unlatching mechanism 180 enables the operator
to release the ramp platform 28 from the deployed or stowed
positions. The operator may then push the ramp platform 28 rearward
to stow it in the rectangular enclosure 24. Alternatively, if
electrical power is unavailable, a mechanic can operate the manual
unlatching mechanism 180 to release the ramp platform 28 in order
to physically extend the ramp platform for servicing.
[0107] The manual unlatching mechanism 180 (FIG. 19) includes a cam
lever 182 located adjacent to and between the deployed latch plates
146, 148. The cam lever 182 is pivotally attached at one end to a
pin 183 that is fixed to the bottom panel 38. The opposite end of
the cam lever 182 includes a convex surface 181.
[0108] A wire cable 184 is attached to the rear end of the cam
lever 182. The forward end of the cam lever 182 is attached to an
extension spring 186 (FIG. 24). The wire cable 184 is attached at
an opposite end to a T-handle 194 (FIG. 2) having a threaded rod
196. The threaded rod 196 (FIG. 19) is inserted through and
supported by a guide tube 198 attached to the rectangular enclosure
24. The guide tube 198 also limits the full stroke of the T-handle
194 by its length. The wire cable 184 extends rearwardly from the
cam lever 182 along the top surface of the bottom panel 38 and
wraps around a wire rope pulley 200 located at the end panel 36
adjacent the structural channel 60. From the wire rope pulley 200,
the wire cable 184 extends along the rearward interior of the
rectangular enclosure 24 to a second wire rope pulley 202 that
extends partly through an opening in the rearward portion of the
side panel 34. At the second wire rope pulley 202, the wire cable
184 exits the rectangular enclosure 24 and extends toward the
forward end of the rectangular enclosure terminating at the
threaded rod 196.
[0109] The wire cable 184 includes a wire rope ball shank 204
swaged to the wire cable along the rearward interior of the
rectangular enclosure, between the two wire cable pulleys 200, 202,
adjacent to the location where the latch arm 122 extends when the
ramp platform 28 is in the stowed position. The latch arm 122
includes a V-notch 208 at its rearward end which is designed to
capture the wire cable 184 when the ramp platform 28 is retracted
to the stowed position.
[0110] When the ramp platform is in the stowed position, the wire
cable 184 extends through the V-notch 208 in the rear portion of
the latch arm 122 (FIG. 25). If power is cut to the ramp assembly
20, the T-handle 194 can be pulled to operate the manual unlatching
mechanism 180. When the T-handle 194 is pulled, the wire cable
extends along the V-notch 208 until the wire rope ball shank 204
engages the rearward end of the latch arm 122, and causes the latch
arm 122 (FIG. 26), as well as the second latch arm 124 (FIG. 28) to
rotate. Rotation of the second latch arm 124 causes the cutout 134
to release from the stowed latch plate 156, and the ramp platform
28 is released. The ramp platform can then be manually
withdrawn.
[0111] When the ramp platform 28 is fully deployed and power is cut
to the ramp assembly 20, the manual unlatching mechanism 180 can be
operated so as to release the ramp platform 28 so that it can be
manually retracted. The rear end of the latch arm 122 includes a
protrusion 210 (FIG. 20). This protrusion 210 is engaged by the
camming surface 181 of the cam lever 182 when the ramp platform 28
is fully deployed and the T-handle 194 is pulled. Engagement of the
protrusion 210 by the cam lever 182 causes the latch arm 122, as
well as the latch arm 124, to rotate and release the deployed latch
plates 146, 148 (FIGS. 21 and 23). In this manner, the manual
unlatching mechanism 180 unlocks the ramp platform 28 and permits
manual retraction of the ramp platform.
[0112] A disconnect coupling or clutch (not shown) can be coupled
between the electrical motor 72 and drive shaft 74 to allow
selective release of the drive pulley from the electrical motor 72,
which would ease manual extension or retraction of the ramp
mechanism. In addition, anti-friction bearings (not shown) at the
shafts for the drive pulley 76 and idler pulleys 78 could reduce
the force required to manually extend or retract the ramp platform
28. Finally, the drive belt 80 could be loosened or removed to
reduce resistance to manual retraction or extension of the ramp
platform 28.
[0113] The ramp assembly 20 of the present invention provides
several advantages over prior art ramps. The lever arms 84 and pins
56 provide a mechanism by which the ramp platform 28 can be
extended and the trailing end of the platform can be lifted, all in
one translational movement. Thus, additional motors or mechanisms
are not needed to lift the rear trailing end of the ramp platform
28. In addition, a transitional plate or other mechanism is not
needed to provide a smooth transition between the ramp platform and
the floor of the low-floor bus 22.
[0114] The present invention also provides the convenient
reciprocating mechanism 26 that includes an electric motor 72 that
is mounted for reciprocating motion with the ramp platform 28. This
design saves space, and does not require a mounting structure for a
motor underneath or behind the rectangular enclosure 24. The coiled
electrical cable 90 permits accessible electrical power for the
electric motor 72 and other components on the rectangular motor
plate 62. Although the power supplied is disclosed as an electric
motor 72, it is to be understood that hydraulic and other power
sources could be used.
[0115] The ramp assembly 20 of the present invention also provides
the manual unlatching mechanism 180, which permits manual release
of the ramp platform 28 at the fully extended or retracted
positions. The ramp platform 28 can then be manually extended or
retracted.
[0116] FIGS. 29-51 show an alternate embodiment of a ramp assembly
300 embodying the present invention. As with the first described
ramp assembly 20, the ramp assembly 300 includes a rectangular
enclosure 24, a reciprocating mechanism 26, and a ramp platform 28.
Like parts on the ramp assembly 20 and the ramp assembly 300
include like reference numerals.
[0117] The ramp assembly 300 includes springs 301 (best shown in
FIGS. 30 and 32) that are attached to the lever arms 302. One of
the springs 301 is attached at one end to an eyelet 303 at the
upper extension of one of the lever arms 302. The opposite end of
the spring 301 is attached to an eyelet 304 located at the rear
inner edge of the adjacent bearing strip 64. A similar spring 301
is mounted on the opposite side of the rectangular motor plate 62
for attachment to the other lever arm 302.
[0118] The springs 301 are helpful in manual deployment of the ramp
platform 28. It has been found that when the ramp platform 28 is
manually deployed, the trailing end of the ramp platform very often
does not lift upward high enough and therefore advance the
rectangular motor plate 62 to engage the latch arms 122, 124 on the
deployed latch plates 146, 148. The springs 301 overcome this
problem by providing a lifting force that raises the trailing end
of the ramp platform 28, and therefore aids in advancement of the
rectangular motor plate 62, during manual extension.
[0119] Because the springs 301 cause the leading ends of the lever
arms 302 to be biased upwards, the top edges 305 (FIGS. 32 and 33)
of the lever arms 302 are shaped differently than the top edges of
lever arms 84 for the first ramp assembly 20. Preferably, the top
edges 305 slope slightly upward so that the top edges 305 can
smoothly ride along and not be impeded by the pins 56. The slope of
the top edges 305 causes the lever arms 302 to move along the pins
56, and permits a smooth, extension of the trailing end of the ramp
platform 28, while guiding the curved slots 86 to the pins 56.
[0120] The springs 301 preferably have a sufficient spring constant
and are sized so that they support approximately one-half the
weight of the ramp of platform 28. The springs 301 therefore
counterbalance the trailing edge of the ramp platform 28 upward,
thus allowing a smooth transition for the curved slots 86 to engage
the pins 56 which also allows advancement of the rectangular motor
plate 62 a sufficient distance so that the deployed latch arms 122,
124 engage, roll over, and latch against the deployed latch plates
146, 148. By providing this function, the springs 301 enable an
operator to manually extend the ramp platform 28 until the ramp
platform is fully deployed without expending much extra effort as
the trailing end of the ramp platform is raised.
[0121] The lever arm 302 includes a removable cam follower 306
(best shown in FIG. 33) attached at its leading end. The removable
cam follower 306 serves the function of the circular bearing 88 of
the previous embodiment, and additionally provides a convenient
manner of removing the ramp platform 28.
[0122] The leading end of the lever arm 302 includes a half
circular open end 307, the opening of which faces forward, and two
threaded holes 308 spaced rearward therefrom. The removable cam
follower 306 is teardrop shaped and includes a sleeve 309 extending
off its rear surface at the larger portion of the tear drop shape.
Two holes 310 are provided that match with the threaded holes 308
on the lever arm 302 and that are countersunk to receive the heads
of cap bolts 311 (FIG. 41). A larger hole 312 that is concentric
with the sleeve 309 is provided at the larger portion of the
teardrop-shape of the removable cam follower 306. The larger hole
312 is aligned so that when the bolts 311 are extended through the
small holes 310 and threaded into the threaded holes 308 on the
lever arm 302, the larger hole 312 is concentric with the half
circular open end 307 of the lever arm 302.
[0123] The larger hole 312 and sleeve 309 on the cam follower 306
are designed so that they fit over a pin 314 that extends sideways
outward from the trailing end of the ramp platform 28. A similar
pin 314 is located on the opposite side of the ramp platform 28 and
is received within a similar removable cam follower 306 attached to
the other lever arm 302. The lever arms 302 and removable cam
followers 306 are spaced apart so that the pins 314 on opposite
sides of the ramp platform 28 are received by and held against the
cam followers 306 when the cam followers are tightened against the
lever arms 302 by the cap bolts 311. The sleeve 309 is also seated
against the half circular open end 307 of the lever arm 302.
[0124] The cap bolts 311 include a tool receiving pattern such as a
hex socket head. By placing a tool into the tool receiving pattern
and rotating the bolts 311, one of the removable cam followers 306
can be loosened and removed, releasing the respective pin 314 on
that side of the ramp platform 28. The ramp platform 28 can then be
lowered to move away from the lever arm 302, and then can be pulled
so that the opposite pin 314 is pulled out of the hole 312 and
sleeve 309 on the opposite removable cam follower 306. In this
manner, the ramp platform 28 is removed from the ramp assembly 300
by disassembly of only one removable cam follower 306. This feature
provides a simpler disconnect procedure for the ramp platform 28 if
repair or maintenance needs to be performed.
[0125] The removable cam followers 306 are preferably formed from a
low-friction bearing material. This material permits the removable
cam followers 306 to freely slide between the support bearings 54
and guide bars 46.
[0126] It has been found that upon manual release by the manual
unlatching mechanism 180 of the deployed latch arms 122, 128 from
the deployed latch plates 146, 148, the weight of the ramp platform
28 pulls the lever arms 302 down a sufficient amount to retract the
rectangular motor plate 62 into the rectangular enclosure 24 so
that when the manual unlatching mechanism 180 is released, the
deployed latch arms do not re-engage the deployed latch plates. To
provide a similar function, a push-off spring mechanism 320 (best
shown in FIG. 31) is provided on the rectangular motor plate 62 to
initiate movement of the rectangular motor plate and the ramp
platform 28 upon manual release in the stowed position. The
push-off spring mechanism 320 initiates movement of the rectangular
motor plate 62 upon manual release of the cutout 134 on the
rearward end of the latch arm 124 from the stowed latch plate
156.
[0127] As can be seen in FIG. 31, the push-off spring mechanism 320
includes a bracket 322 extending perpendicularly upward from the
face of the rectangular motor plate 62. The bracket 322 includes a
hole (not shown) extending parallel to the rectangular motor plate
62. A bolt 324 extends through a spring 326, into a spring
retaining sleeve 328, and out through the hole. A nut 330 is
threaded onto the end of the bolt that extends out of the hole. The
opposite end of the bolt 324 is positioned so that it extends
slightly rearward beyond the end of the rectangular motor plate 62.
In operation, the head of the bolt 324 engages the end panel 36 of
the rectangular enclosure 24. When the ramp platform 28 is in the
stowed position, the spring 326 is slightly compressed. Actuation
of the manual unlatching mechanism 180 causes the spring 326 to
relax (extend) and push the rectangular motor plate 62 away from
the end panel 36. This movement by the rectangular motor plate 62
away from the end panel 36 is sufficient to prevent the cutout 134
on the rearward end of the latch arm 124 from re-engaging the
stowed latch plate 156 after manual release.
[0128] The ramp assembly 300 also incorporates a delay circuit 334
(FIG. 34) for more efficient operation of the solenoids 144 and the
motor 72. Applicants have found that when power is supplied to the
rectangular motor plate 62, the motor 72 begins movement of the
rectangular motor plate 62 faster than the solenoids 144 release
the latch mechanism 120. This lag in movement by the latch
mechanism 120 is due largely to the weight of the latch mechanism
120. The motor 72 has a tendency to attempt to move the rectangular
motor plate 62 immediately upon receiving power and before the
latch arms 122, 124 have released from either the deployed latch
plates 146, 148, or the stowed latch plate 156. To solve this
problem, the present invention provides the delay circuit 334 shown
in FIG. 34.
[0129] The delay circuit 334 introduces a time delay between
actuation of the solenoids 144 and start of the motor 72. The delay
circuit 334 utilizes delay circuitry (not shown, but well known in
the art) to properly space the time between the start of the
solenoids 144 and start of the motor 72, so that the latch arms
122, 124 are fully released before the motor 72 attempts to move
the rectangular motor plate 62.
[0130] Applicants have also found it to be advantageous to use
similar timing circuitry within the delay circuit 334 to deactuate
the solenoids 144 simultaneously with start of the motor 72.
Because start of the motor 72 occurs more rapidly than deactuation
of the solenoids 144 can cause return of the latch mechanism 120 by
the spring 150 and the return stroke of the solenoids 144, the
motor moves the rectangular motor plate 62 before the latch arms
122, 124 can re-engage the latch plates. In addition, by
deactuating the solenoids 144 at the same time the motor 72 is
started, the solenoids and the motor are not powered at the same
time. This results in less power having to be provided to the
rectangular motor plate 62.
[0131] A sensor switch 340 (FIG. 31) is provided on the trailing
end of the rectangular motor plate 62. The sensor switch 340
engages the end panel 36 when the rectangular motor plate 62 is in
the stowed position. The sensor switch 340 provides an interlock
signal to the low floor bus 22 upon engagement of the sensor switch
340 with the end panel 36. The interlock signal is an indication
that the ramp platform 28 is in the stowed position. The interlock
signal can be wired to an interlock in the bus electrical system so
as to prevent travel of the bus when the ramp platform 28 is not in
the stowed position. Alternatively, the interlock signal can light
an indicator lamp at the control panel for the bus driver, or other
indicators could be provided.
[0132] The ramp assembly 300 includes an adjustable deployed latch
plate 342 (shown in relation to the ramp assembly in FIG. 51). The
underside of the adjustable deployed latch plate 342 is shown in
FIG. 36. The adjustable deployed latch plate 342 includes a
rectangular raised section 344 that extends along the bottom side
of the deployed latch plate. The rectangular raised section 344 is
configured to fit within a rectangular elongate cutout 346 in the
bottom panel 38 (FIG. 35). The rectangular elongate cutout 346 is
longer than the rectangular raised section 344, but only slightly
larger in width, which permits the adjustable deployed latch plate
342 to fit within and slide along the rectangular elongate cutout.
The adjustable deployed latch plate 342 includes a number of
threaded holes 348 (FIG. 36) extending into the bottom of the latch
plate and located on opposite sides of the rectangular raised
section 344. The threaded holes 348 align with elongate slots 350
on the bottom panel 38 (FIG. 35). Screws 352 extend through the
elongate slots 350 into the threaded holes 348.
[0133] A rod 354 is threaded into a female threaded hole 356 that
extends into the aft section of the adjustable deployed latch plate
342. The threaded rod 354 includes a tool receiving pattern 358,
such as the head of a bolt, at its distal end. A five-sided box 359
is attached to the aft end of the adjustable deployed latch plate
342, over the end of the threaded rod 354. The five-sided box 359
keeps dirt and other road grime from entering the ramp assembly 300
through the rectangular elongate cutout 346.
[0134] An abutment surface in the form of a metal protrusion 360 is
located on the top surface of the bottom panel 38 just rearward of
the end of the rectangular elongate cutout 346. The metal
protrusion 360 can be formed integral with the bottom panel 38,
punched out of the bottom panel, welded integral with the bottom
panel, or can be formed in other conventional methods.
[0135] In practice, the adjustable deployed latch plate 342 is
arranged so that the rectangular raised section 344 extends into
the rectangular elongate cutout 346. The screws 352 extend through
the elongate slots 350 and into the threaded holes 348. The screws
352 are not tightened until the adjustable deployed latch plate 342
is properly aligned relative to the latch arm 124. To properly
align the adjustable deployed latch plate 342, the rectangular
raised section 344 is slid along the rectangular elongate cutout
346 until the adjustable deployed latch plate 342 is approximately
aligned with the cutout 132 on the latch arm 124 when the
rectangular motor plate 62 and the ramp platform 28 are in the
fully deployed position. A tool (not shown) that fits on the tool
receiving pattern 358 rotates the threaded rod 354 until the
threaded rod abuts against the metal protrusion 360. Further
rotation of the threaded rod 354 moves the adjustable deployed
latch plate 342 toward the front of the rectangular elongate cutout
346. By maintaining the threaded rod 354 snugly against the metal
protrusion 360, rotation of the threaded rod provides minute
adjustments of the adjustable deployed latch plate 342. In this
manner, the adjustable deployed latch plate 342 can be aligned so
that latch arm 124 fits precisely over the latch plate when the
ramp platform is in the fully deployed position.
[0136] Preferably, a second adjustable deployed latch plate 362
(FIG. 51) is provided for alignment with the cutout 130 of the
other latch arm 122. The details of the second adjustable deployed
latch plate are not shown, but could be similar to the adjustable
deployed latch plate 342 described. The adjustable deployed latch
plates 342, 362 provide a method for properly aligning the latch
plates with the latch arms 122, 124 that is accessible from the
bottom (outside) of the rectangular enclosure 24.
[0137] A manual unlatching mechanism 366 is provided for the ramp
assembly 300 that is substantially the same as the manual
unlatching mechanism 180 described with reference to the ramp
assembly 20. However, a different handle 368 (best shown in FIG.
41) is utilized in the manual unlatching mechanism 366. The handle
368 includes a loop 370 at a forward end that is attached to a
hexagonal rod 372. The hexagonal rod 372 extends through a
hexagonal slot 374 in a bracket 376 that extends perpendicular from
the side panel 34 of the rectangular enclosure 24. The hexagonal
rod 372 includes a rounded circumferential groove 378 spaced from
the distal end of the hexagonal rod. Just forward of the rounded
groove 378, a cap bolt 380 extends radially into the hexagonal rod
372. The head of the cap bolt 380 extends out of the side of the
hexagonal rod 372.
[0138] The front end of the handle 368 extends through a hole (not
shown) in the bracket 41. The loop 370 is normally positioned
between the bracket 41 and the hinged closure panel 42.
[0139] A release tool 382 (FIG. 50) is used to unlatch the manual
unlatching mechanism 366. The release tool includes a handle 384, a
hook 386, and a round tube (or rod) 388 extending from the handle
to the hook. The hook 386 is sized so that it can fit within the
loop 370 of the handle 368, and can extend over one side of the
loop.
[0140] In practice, the release tool 382 is gripped at the handle
384 by an operator, and the hook 386 is extended into the loop 370
of the handle 368 of the manual unlatching mechanism 366. The
operator may have to open the hinged closure panel 42 to access the
handle 368. The operator pulls outward on the release tool 382,
which pulls outward the handle 368. The handle 368 is attached to
the wire cable 184, and pulling outward on the handle rotates the
latch arms 122, 124 as was described with reference to the first
ramp assembly 20.
[0141] The hexagonal shapes of the hexagonal rod 372 and the
hexagonal slot 374 prevent rotation of the hexagonal rod and
maintains the loop 370 in alignment so that it can extend out of
and retract into the frame 41. The hexagonal rod 372 is pulled
outward until the cap bolt 380 abuts against the bracket 376. The
contact of the cap bolt 380 with the bracket 376 precludes further
extension of the hexagonal rod 372.
[0142] During extension of the handle 368, the manual unlatching
mechanism 366 releases the latch arms 122, 124 from the deployed
latch plates 342, 362 or the stowed latch plate 156. After the
latch arms 122, 124 are released, the operator can stop pulling on
the handle 368, and the spring 186 returns the handle 368 into
position against the bracket 41. Although actuation of the manual
unlatching mechanism 366 is described with reference to use of a
release tool 382 by an operator, it is to be understood that the
handle 368 of the manual unlatching mechanism 366 could be gripped
by the fingers of an operator, or could be pulled outward using
other methods.
[0143] The ramp assembly 300 incorporates a drive belt clutch
mechanism 398 (FIG. 44) and a manual belt release mechanism 400
(FIG. 38). In summary, the two mechanisms 398, 400 work together so
that a belt release assembly 402 of the manual belt release
mechanism 400 relaxes the drive belt 404 (i.e., removes tension),
and the drive belt clutch mechanism 398 separates the drive belt
404 from operation of the motor 72. In this manner, the ramp
platform 28 can be manually extended and retracted without the
resistance of the motor 72 against the drive belt 404. The manual
belt release mechanism 400 will be described below, followed by a
description of the drive belt clutch mechanism 398.
[0144] The manual belt release mechanism 400 includes a belt
release assembly 402 (FIG. 39) that is attached to the drive belt
404. The belt release assembly 402 includes a toothed belt clamp
406. The toothed belt clamp 406 is a flat plate with a series of
slots 408 extending from front to back along its center and a
cutout 410 just forward of the slots. Threaded holes 412 are
aligned along both sides of the slots 408. At the front, top end of
the toothed belt clamp 406 are two triangular cutout recesses
414.
[0145] A separate belt tensioner link 416 (FIG. 39) is pivotally
mounted from the apex of each of the triangular cutout recesses
414. Pins 418 extend through each of the belt tensioner links 416,
through the toothed belt clamp 406 at the apex of the triangular
cutout recesses 414, and into an additional set of belt tensioner
links 420 on the opposite side of the toothed belt clamp 406. Thus,
each pin 418 acts as a pivotal mount for both a belt tensioner link
416 located on the top of the toothed belt clamp 406 and located
within the triangular cutout recesses 414, and a belt tensioner
link 420 located underneath the toothed belt clamp 406. The belt
tensioner links 416, 420 extend forward to opposite sides of
eccentric pivot mounts 422, 424 (best shown in FIG. 43). The
eccentric pivot mounts 422, 424 each have a flanged bearing 428
extending therethrough. L-brackets 430, 431 extend upward from the
eccentric pivot mounts 422, 424.
[0146] The eccentric pivot mounts 422, 424 are rotatably mounted on
pins 456 that extend into the structured channel 60. The tops of
the pins 456 are shown in FIG. 30, and the bottoms of the pins are
shown in FIG. 42. The belt tension links 416, 420 are pivotally
mounted about pins 426 (one shown in FIG. 43, one shown in FIG. 38)
that are eccentrically mounted about the pin 456 on the eccentric
pivot mounts 422, 424.
[0147] A drive cam 432 (FIG. 39) is attached to the L-bracket 430
of the eccentric pivot mount 422, and a driven cam 434 is attached
to the L-bracket 431 of the opposite eccentric pivot mount 424. The
drive cam 432 includes a half circular plate 435 having teeth 436
along an outer edge of the circumference of the half circle, and a
lever arm 438 fixed at one end of the circumference of the half
circle. The lever arm 438 extends outward in a plane from the plate
435 and bends at a distal end at a right angle to form a spring
attachment 440. A pin 442 is located adjacent to the angle formed
between the spring attachment 440 and the lever arm 438.
[0148] The driven cam 434 includes a quarter circle plate 443
having teeth 444 along an outer edge of the circumference of the
quarter circle, and arranged to engage the teeth 436 on the drive
cam 432. The drive cam 432 and the driven cam 434 both include
flanged bearings 446 aligned with the flanged bearings 428 in the
eccentric pivot mounts 422, 424. The pins 456 extend into the pairs
of flanged bearings 446, 428.
[0149] Turning now to FIG. 37, the belt release assembly 402 is
mounted just below the structural channel 60 at the rearward
portion of the rectangular enclosure 24 (location relative to the
entire ramp assembly 300 is shown in FIG. 51). A pair of grooved
bearings 450 are mounted on opposite sides of the structural
channel 60 to slidingly receive the side edges of the toothed belt
clamp 406. Teeth on the drive belt 404 extend between the slots 408
on the toothed belt clamp 406. A drive belt clamp plate 452 is
attached over the drive belt 404 and the toothed belt clamp 406 so
as to capture the drive belt 404. The drive belt clamp plate 452 is
held in position against the toothed belt clamp by a series of
fasteners 454 that extend through holes (not shown) in the drive
belt clamp plate 452 and into the threaded holes 412 in the toothed
belt clamp 406.
[0150] Referring now to FIG. 38, the pins 456 extend through the
top of the structural channel 60 and downward through the flanged
bearings 446, 428, on the eccentric pivot mounts 422, 424 and the
drive cam 432 and driven cam 434. The drive cam 432 and driven cam
434 are thus mounted for rotation with the eccentric pivot mounts
422, 424 about the pins 456.
[0151] A pair of springs 460 (full mounting shown in FIG. 37) are
each attached at one end to a bracket 462 on the back side of the
end panel 36, and attached at the other end to the spring
attachment 440 on the lever arm 438 of the drive cam 432. A belt
release cable 464 is attached at the pin 442 on the lever arm 438
of the drive cam 432. The belt release cable 464 extends from the
pin 442 along the back of the end panel 36 (FIG. 51) through a
pulley 466 and forward to a handle 470 mounted just below the
handle 368 for the manual unlatching mechanism 366. The handle 470
includes a similar structure to the handle 368, including a loop
370, hexagonal rod 372, rounded groove 378, and cap bolt 380. The
handle 470 for the manual belt release mechanism 400 extends
through a hexagonal slot 472 in the bracket 376 that includes a
cutout 474. The cutout 474 is arranged opposite the side panel 34
and extends radially outward from the circumference of the
hexagonal slot 472. The cutout 474 is slightly larger than the head
of the cap bolt 380, the function of which will be described in
detail below. The handle 470, like the handle 368, is accessible
between the bracket 41 and the hinged closure panel 42 (FIG.
41).
[0152] The operation of the manual belt release mechanism 400 will
now be described. If manual retraction or deployment of the ramp
platform 28 is desired, the manual belt release mechanism 400 is
actuated so as to release the drive belt 404. To do this, the
hinged closure panel 42 is manually opened and the loop 370 of the
handle 470 is grasped by the hook 386 of the release tool 382. The
operator pulls on the release tool 382, causing the handle 470 to
extend outward from the bracket 41 (FIG. 40). Pulling the handle
470 outward in this manner causes the head of the cap bolt 380 to
be pulled through the cutout 474. The rounded groove 378 is aligned
with the hexagonal slot 472, which permits the handle 470 to be
rotated 90 degrees to extend downward (FIG. 41) so that the head of
the cap bolt 380 is no longer aligned with the cutout 474. In this
position, the handle 470 cannot retract, because the contact
between the head of the cap bolt 380 and the bracket 376 prevents
movement of the handle rearward. The handle 470 is positioned so
that it holds the hinged closure panel 42 open, allowing the
operator access to the handle 368 for the manual unlatching
mechanism 366.
[0153] Pulling outward on the handle 470 causes the belt release
assembly 402 to release tension on the drive belt 404. In normal,
tensioned mode of the drive belt 404, the belt release assembly 402
is in the position shown in FIG. 39. In this arrangement, the belt
tension links 420, 416 are in an over-center eccentric position.
That is, the tension in the drive belt 404 and the eccentric
mounting of the belt tension links 416, 420 on the eccentric pivot
mounts 422, 424 biases the drive cam 432 and the driven cam 434
into the positions shown in FIG. 39, and in a direction opposite of
the arrows shown on the surfaces of the drive cam and driven cam.
The springs 460 also pull the lever arm 438 and therefore the drive
cam 432 in a direction that is opposite the arrows.
[0154] By pulling on the handle 470, the belt release cable 464
pulls the lever arm 438 so that the drive cam 432 and driven cam
434 are rotated in the direction of the arrows in FIG. 39. At the
beginning of this rotation, the belt tension links 416, 420 resist
movement because of the over-center location of the belt tension
links relative to their eccentric mounting on the eccentric pivot
mounts 422, 424. Once this initial resistance is overcome, the pins
426 at the upper end of the belt tension links 416, 420 are rotated
by and about the eccentric pivot mounts 422, 424 to the opposite
side of the axis of rotation of the drive cam 432 and the driven
cam 434 (i.e., the pins 456). The pulling force on the belt release
cable 464 then causes further rotation of the drive cam 432 and the
driven cam 434 to the position shown in FIG. 43. In this position,
the belt tension links 416, 420 have been rotated by the eccentric
pivot mounts 422, 424 so that the pins 426 are forward of the pins
456. Moving the belt tension links 416, 420 eccentrically in this
manner moves the toothed belt clamp 406 forward in the grooved
bearings 450. This movement forward releases the tension on the
drive belt 404, and creates slack in the drive belt.
[0155] To re-tension the drive belt 404, the handle 470 is rotated
so as to align the cap bolt 380 with the cutout 474, and the handle
470 is allowed to retract under the tension of the springs 460.
Preferably, the tension of the springs 460 is sufficient to
withdraw the handle 470 and overcome the tension of the drive belt
404 so as to pull the belt tension links 416, 420 back to the
over-center position (shown in FIG. 39). Upon full release of the
handle 470 and return of the belt release assembly to the position
shown in FIGS. 37-39, the drive belt 404 is fully tensioned and
locked into place. Retraction of the handle 470 permits the hinged
closure panel 42 to once again be closed.
[0156] The drive belt clutch mechanism is shown in FIGS. 44-47. The
drive belt clutch mechanism 398 includes a drive pulley 480 mounted
parallel to and between two idler pulleys 482 (FIG. 44). The drive
pulley 480 includes a clutch groove 484 extending around its
circumference and located at its center. The drive pulley 480 is
mounted for rotation about a drive shaft 486 that extends through
front and rear pulley mounting plates 488, 490. The drive pulley
480 includes teeth 485 around its perimeter except at the clutch
groove 484. The teeth 485 are spaced so as to receive the teeth on
the drive belt 404.
[0157] The idler pulleys 482 are mounted on idler shafts (not
shown) for rotation thereon. Bolts 492 extend through spring guides
494 and through the pulley mounting plate 488 or 490 and into the
idler shafts. The spring guides 494 are rings with a
circumferential groove.
[0158] A clutch saddle 496 (FIG. 45) rests across the top of the
pulley mounting plates 488, 490, and is held in position by two
springs 498. The clutch saddle 496 includes two mounting plate bars
500 attached by two cross braces 502. The cross braces 502 and the
mounting plate bars 500 form a rectangle, and the mounting plate
bars extend beyond the rectangle. At distal ends of the mounting
plate bars 500 are spring arm attachments 504 that extend downward
at approximately a 90.degree. angle to the mounting plate bars.
Holes 506 are located on the spring arm attachments 504 for
receiving the ends of the springs 498.
[0159] A clutch band 508 extends across and forms a downward loop
between the two cross braces 502. The clutch band 508 includes two
cross brace attachments 510 and a bottom rounded section 512 for
fitting about the clutch groove 484 of the drive pulley 480. As can
best be seen in FIGS. 46 and 47, the clutch band 508 is configured
such that the radius of curvature of the rounded section
substantially matches the radius of curvature of the outer
circumference of the teeth 485 on the drive pulley 480. Two
flattened sections 514 are formed at the outer ends of the bottom
rounded section 512 for directing the drive belt 404 away from the
teeth of the drive pulley 480. The clutch band 508 extends
substantially straight upward from the flattened sections 514 to
the cross brace attachments 510.
[0160] The clutch saddle 496 is preferably formed as a weldment of
stiff metal, such as steel. The springs 498 are attached to the
spring arm attachments 504 and extend under the spring guides 494.
The springs 498 bias the clutch saddle downward against the upper
surface of pulley mounting plates 488, 490, toward the position
shown in FIG. 47.
[0161] In operation, when the drive belt 404 is tensioned, the
tension of the drive belt pulls the clutch saddle 496 upward into
the position shown in FIG. 46 so that the teeth of the drive belt
engage the teeth 485 of the drive pulley 480. The drive belt 404 is
wider than the clutch groove 484, so it extends across the clutch
groove to engage the teeth 485 on both sides of the clutch groove.
When the drive belt 404 is released by the belt release assembly
402, the springs 498 urge the clutch saddle 496 downward, and push
the teeth of the drive belt 404 out of engagement with the teeth of
the drive pulley 480. In this manner, the ramp platform 28 can be
extended and retracted with the drive belt 404 released from the
drive pulley 480 so that an operator does not have to turn the
motor upon extension and retraction.
[0162] It is important that the tension of the springs 498 not be
too strong so as to stretch the drive belt 404 or bend the clutch
saddle 496 during operation. Instead, a spring tension should be
selected such that the force downward on the clutch saddle 496 by
the springs 498 is sufficient to take the slack in the released
drive belt 404 and move that slack downward by the pressure of the
clutch saddle 496.
[0163] The ramp platform 28 includes an elongate slot 520 along its
leading end. During manual extension of the ramp platform 28, the
hook 386 on the release tool 382 can be inserted into the elongate
slot, and the operator can pull the ramp platform 28 outward. This
operation permits the operator to extend the ramp platform 28
without inserting hands into the rectangular enclosure 24 or having
to bend over to reach the ramp platform 28.
[0164] The components of a belt tensioner 530 for the drive belt
404 are shown in FIGS. 48 and 49. A stationary plate 532 (FIG. 49)
including a groove 534 for receiving the drive belt 404 is mounted
to the underside of the structural channel 60. The stationary plate
532 includes mounting holes 535 on opposite sides of the groove
534. An adjustable clamp 536 (FIG. 48) is mounted between the
stationary plate 532 and a metal plate 537 that extends under the
structural channel 60. The adjustable clamp includes a series of
ribs 538 extending along its middle and two elongate slots 540
extending along the sides of the ribs. A grasping slot 542 is
located at the front end of the ribs 538, and a flange 543 is
aligned across the front of adjustable clamp 536.
[0165] To mount the drive belt 404, the teeth of the drive belt are
matched with the ribs 538 of the adjustable clamp 536, and the
opposite, smooth side of the drive belt is arranged within the
groove 534 of the stationary plate 532. Fasteners such as screws or
bolts 544 (only one shown in FIG. 52) are extended (through the
holes 535 on the stationary plate 532) through the slots 540, and
into the metal plate 537. The bolts 544 are anchored into the metal
plate 537.
[0166] The bolts 544 are not tightened against the adjustable clamp
536 and stationary plate 532 until the drive belt 404 is tensioned.
To tension the drive belt 404, a hook, screwdriver, or other tool
is inserted into the grasping slot 542 and the adjustable clamp 536
is pulled outward relative to the stationary plate 532 so as to
tension the drive belt. The adjustable clamp 536 and the grasping
slot 542 are arranged so that they can be accessed when the hinged
closure panel 42 is open, underneath upper cross member 58 of the
rectangular enclosure 24. Once the drive belt 404 has sufficient
tension, the bolts 544 are tightened to hold the adjustable clamp
536 into position. In this manner, the drive belt 404 is
tensioned.
[0167] Periodically, after several extensions of the ramp platform
28, the drive belt 404 may be stretched, and may require
tightening. To do this, the bolts 544 are loosened, a tool is
placed in the grasping slot 542, and the drive belt 404 is
tightened. The bolts 544 can then be retightened so as to fix the
position of the adjustable clamp 536.
[0168] The ramp assembly 300 includes close-out bearings 552 (FIG.
41) formed of a low friction material such as Delrin. The close-out
bearings 552 perform much of the same function as the V-shaped
brackets 44 of the ramp assembly 20. However, the close-out
bearings 552, because of the low friction material, do not damage
or scratch the ramp platform 28 upon extension and retraction of
the ramp assembly 300.
[0169] A wire rope retainer 560 (FIG. 53) is provided for the
pulley 466. The wire rope retainer 560 is mounted over the pulley
466 so that the pulley freely spins therein. The wire rope retainer
560 is a single piece of metal that forms a U-bracket 561 that
extends around the outside of the pulley 466 and is attached at the
axle of the pulley on opposite sides of the pulley. A flange 562
extends along one side of the pulley 466 off of one side of the
U-bracket 561 and upward to form an L-bracket 564 that fits around
an edge of the pulley 466. The L-bracket 564 and the U-bracket 561
form two retainers for holding the cable 464 on the pulley 466.
[0170] A second L-bracket 565 extends outward from the flange 562
in opposite direction of L-bracket 564 and fits into a slot 567
(FIG. 37) of the bottom panel 38 adjacent to the axle 566 for the
pulley 466. The L-bracket 565 prevents rotation of the wire rope
retainer 560 when the manual bolt release mechanism 400 is
actuated. The wire rope retainer 560 retains the cable 464 on the
pulley 466 should cable 464 go slack. The wire rope retainer 560
can also be used in a similar manner around the pulleys 200 and 202
and cable 184 of manual unlatching mechanism 366 or 180.
[0171] While the preferred embodiment of the invention has been
illustrated and described with reference to preferred embodiments
thereof, it will be appreciated that various changes can be made
therein without departing from the spirit and scope of the
invention as defined in the appended claims.
* * * * *