U.S. patent number 3,737,009 [Application Number 05/194,675] was granted by the patent office on 1973-06-05 for wheel chair lift.
Invention is credited to Joseph L. Stoddard.
United States Patent |
3,737,009 |
Stoddard |
June 5, 1973 |
WHEEL CHAIR LIFT
Abstract
A lift is described which provides a convenient and safe means
for lifting objects and/or personnel for a limited height. In
particular, the lift provides a means whereby a person in a wheel
chair may be raised a given distance, such as the height necessary
to enter a trailer. In addition to the basic lifting mechanisms,
the lift provides a safety feature whereby a lip, connected to the
lifting platform and actuated by the upward movement of the
platform, pivots upwardly and prevents an inadvertent roll-off of
the wheel chair. The structure about the platform includes sheet
material about three sides and a hinged flap across the fourth
side. As the platform is raised, the hinged flap, normally urged
into a horizontal position by a spring, is pivotally raised
underneath the rising platform whereby the fourth side is sealed
off to prevent children or pets from crawling under the raised
platform with subsequent injury should the platform lower upon
them. On descent, the frontal lip pivots forwardly and downwardly
whereby, when the platform contacts the ground, the lip will
provide a short ramp to the ground. Simultaneously, the flap,
raised into an upright position on ascent, pivots to a horizontal
position under force of the spring.
Inventors: |
Stoddard; Joseph L. (Tucson,
AZ) |
Family
ID: |
22718483 |
Appl.
No.: |
05/194,675 |
Filed: |
November 1, 1971 |
Current U.S.
Class: |
187/282; 187/200;
187/217; 187/255; 187/403 |
Current CPC
Class: |
A61G
3/063 (20130101); B66B 9/00 (20130101); A61G
2200/14 (20130101) |
Current International
Class: |
B66B
9/00 (20060101); A61G 3/06 (20060101); A61G
3/00 (20060101); B66F 11/00 (20060101); B66b
011/04 () |
Field of
Search: |
;187/10,12,20,51,62,98,9,94,17,8.52 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hornsby; Harvey C.
Claims
I claim:
1. A vertically moving platform assembly within a supporting and
guiding framework, including a base having a plurality of sides, a
barrier extending upwardly from less than all the sides thus
providing at least one open side, and power means for raising the
platform, comprising:
a hinged lip pivoted to one edge of the platform for providing a
ramp for ease of ingress and egress when the latter is in its
lowered position,
flexible means connected between said lip and said platform for
rotating said lip upwardly in response to an upward movement of the
platform,
a hinged flap pivoted to said open side of the base of the
framework about a horizontal pivot point for movement between a
horizontal position beneath said platform when said platform is a
lowered position and a raised vertical position upon elevation of
said platform, said flap being at all times disposed beneath a
plane defined by the platform, and
flexible means connected between said flap and said platform for
pivoting said flat upwardly about said horizontal pivot point in
response to an upward movement of the platform to form a continuous
barrier about the raised platform, whereby a load elevated by the
platform will be retained on said platform by said lip and the
barrier will prevent ingress of foreign objects beneath the raised
platform.
2. A vertically moving platform assembly as claimed in claim 1,
comprising:
a counterweight system attached to the platform and co-operating
with the framework, whereby vertical movement of an unloaded
platform must be initiated by an outside force.
3. A vertically moving platform assembly as claimed in claim 1,
wherein said pivoting means comprises:
a spring connected between said flap and the framework for urging
said flap to a horizontal position, and
a cord connected between said flap and the platform, whereby
movement of the platform is translated through said cord into a
pivotal movement of said flap counter to the spring force.
4. A vertically moving platform assembly as claimed in claim 1,
wherein said rotating means comprises:
a cord having one end attached to said lip and the other end
attached to the platform assembly, and
a pulley attached to the framework for engaging said cord, whereby
movement of the platform relative to the framework will shorten the
effective cord length causing said lip to rotate upwardly.
5. The power means as claimed in claim 1, comprising:
an electric motor attached to the framework,
means for converting the rotary output of said electric motor into
a vertically moving element, and
means for connecting said element to the platform, whereby the
rotary output of said electric motor is translated into a vertical
movement of the platform.
6. The power means as claimed in claim 5, including:
a manually operated switch for energizing said electric motor,
and
an automatically operated switch for de-energizing said electric
motor when the platform has reached its apex.
7. The power means as claimed in claim 6, wherein
said manual switch is attached to the platform, and
said automatic switch is actuated in response to a predetermined
relative movement between the framework and the platform.
Description
This invention relates to that class of devices useful for raising
loads for a limited distance.
Recently developing sociological and economical changes have made
trailers and trailer courts extremely popular among the elderly,
particularly those who lived on limited means, that is, on pensions
or annuities. Many of these persons are physically handicapped
because of senescence or injury and some may in fact be incapable
ofwalking for any extended distance. For this class of persons, who
are relegated to a wheel chair for mobility and who are incapable
of ascending steps without aid, there is a serious problem in
mounting the entrance steps to their trailer. The use of inclined
ramps leading up the the trailer have been attempted; however,
these suffer from two very serious disadvantages. First, the ramp
requires an extended amount of ground surface area in order to
maintain a gradual slope. This is an impossibility in a crowded
trailer park. The second problem arises in that many of this class
of persons are not physically powerful enough to propel themselves
up even a gradual ramp. Thus, their mobility is dependent on the
use of an electric or otherwise powered wheel chair. These wheel
chairs are expensive and beyond the means of many persons within
this class.
A solution in the past has been that of employing one of the
commercially available lifts. This solution was unsatisfactory in
that many of these lifts were either very expensive and beyond the
means of the aforementioned class of persons, or else did not
provide sufficient safety features to permit the user to employ the
lift without fear of possible injury.
It is therefore a primary object of the present invention to
provide a lift for a wheeled vehicle which incorporates
interlocking safety features whereby the occupants may employ the
lift without fear of personal injury.
Another object of the present invention is to provide a lift for a
wheeled vehicle which does not present a safety hazard to crawling
children or pets.
Another object of the present invention is to provide a raised lip
to prevent wheeled loads from rolling off the raised platform.
Still another object of the present invention is to provide an
interlocked pivotal side co-operating with three fixed sides to
establish a surrounding barrier beneath the raised platform.
These and other objects of the present invention will become
apparent to those skilled in the art as the description thereof
proceeds.
In describing the invention with more specificity, reference will
be made to the following drawings, in which:
FIG. 1 illustrates the basic structure taught in accordance with
the teachings of the present invention.
FIG. 2 illustrates a cross section of the basic structure taken at
line 2--2 of FIG. 1.
FIG. 3 illustrates the hinged flap forming the fourth side of the
barrier surrounding the platform.
FIG. 4 illustrates a cross section of the basic structure taken at
line 4--4 of FIG. 2.
Referring to FIG. 1, there is shown a lift assembly built according
to the invention. The framework of the lift assembly includes four
upright supports 1, 2, 3, and 4, which are attached to a flat
rectangular base 73. The front upright supports 1, 2 are connected
by horizontal bars 5 and 6 to the rear extended upright supports 3
and 4, respectively. Supports 3 and 4 are braced by diagonal
members 7 and 8 extending from points in proximity to the junction
of support 1 and horizontal bar 5 and support 2 and horizontal bar
6 to the upper portion of supports 3 and 4, respectively. In this
fashion, the uprights 1, 2, 3, and 4, including their respective
connecting members, form three sides of the lift framework.
Extending upwardly from the base 73 and along each of these three
sides, defined by uprights 1 and 3, 3 and 4, and 4 and 2, there may
be barriers 9, 10, 11, respectively, of sheet-like material or
screening. The height above the base 100 of these barriers should
be at least equal to the height of the raised position of the
platform 14. If desired, the barriers 9, 10, and 11 may be designed
to serve both as an additional support for uprights 1, 2, 3, and 4
and as a shroud about the platform 14. Additional bracing, such as
triangles 12 and 13, may be welded to uprights 1 and 2 and the base
73, to add rigidity to the structure.
The vertically moving platform assembly includes a platform 14 and
two vertical sides 15 and 16 extending upwardly from opposite sides
of the platform 14. Triangular braces 17 and 18 may be welded to
the platform 14 to secure the respective sides and provide
additional rigidity. Channel members 19 and 20 are welded to the
sides 15 and 16 respectively to co-operate with uprights 3 and 4,
respectively, and act as guides when raising or lowering the
platform 14. The remaining two sides of the platform 14 do not have
any permanent barriers in order that a wheeled vehicle may be
rolled onto the lowered platform 14 from the front and off the rear
of platform 14 when the platform 14 is in the raised position.
A pivotable lip 21 is attached to and extends across the front
portion of th platform 14. A cord or cable 22 is attached to the
front corner of the lip 21 and extends therefrom through a pulley
74 attached to an upper portion of barrier 9 and then attaches to
the upper portion of the side 15. In operation, the lip 21
functions as follows. When the platform 14 is in the lowered
position, the lip 21 acts as a ramp to permit an easy entry for a
wheeled vehicle onto the platform 14. As the platform 14 begins to
rise, the effective cord length between the lip 21 and the upper
portion of side 15 tends to be shortened due to the immobility of
the pulley 74 through which the cord 22 must pass. Thus, the front
of the lip 21 is forced to pivot upwardly toward platform 14.
Thereby, the lip 21 pivots upwardly beyond horizontal to provide an
upward incline for a vehicle carried on the platform 14; thus, the
vehicle is inhibited from rolling off the platform 14. If desired,
a second cord 23 may be used at the other side of the platform,
operating in the previously described manner.
Each of the supports 3 and 4 includes shelf 24, 25 mounted in
proximity to the top portion of the respective uprights. Each of
these shelves 24, 25 supports a journalled sprocket 26, 27
respectively. The lower part of supports 3 and 4 include
journalling means 75, 76 co-operating with an axle 34 extending
beyond the side of either one of the supports. Attached to either
end of axle 34 are sprockets 28, 29. A pair of chains 32, 33, which
may be in the nature of bicycle chains, extend about sprockets 26,
28 and 27, 29 respectively. An extension 30 and 31 is attached to
each of the platform sides 15 and 16, and clamped, or otherwise
secured to each of the chains 32, 33, such that the platform may
not be raised nor lowered without causing sprockets 28, 29 and
ultimately axle 34 to rotate. Thus, any rotation of axle 34 will
cause the platform 14 to ascend or descend, depending on the
direction of rotation. A sprocket 35 is rigidly attached to axle 34
in proximity to sprocket 28. A support structure 37 attached to the
side of the lift framework supports a journalled axle 38. Pulley 39
and sprocket 40, operating as a rotating unit, are mounted on axle
38. Chain 36 connects sprocket 40 to sprocket 35 whereby any
rotation of pulley 39 will necessarily cause some rotation of axle
34. An electric motor 24 having a pulley 42 attached to the
armature thereof drives pulley 39 through a belt 41
In operation, rotation of the armature of motor 24 necessarily
rotates pulley 39 and sprocket 40. Sprocket 35, through movement of
chain 36, causes axle 34 to rotate. As sprockets 28 and 29 are
firmly attached to axle 34, sprockets 26 and 29 will be rotatably
driven through chains 32 and 33. Any movement of the chains 32, 33
will cause the platform 14 to move upwardly or downwardly due to
the interconnection through attachments 30 and 31.
A pair of counterweights 43, 44 attached by cords 45, 46 to the
platform 14 through pulleys 47, 48 are designed to place the
platform 14 in a condition of near equilibrium. That is, without
the application of an outside force, the platform 14 will neither
ascend nor descend.
A switch 49, which may be conveniently placed on the upper edge of
one side of the raised sides of platform 14, such as side 15 as
shown, controls the power to the electric motor 24. The switch 49
is connected so that as it is placed in the "ON" position, the
motor 24 will be actuated, causing the platform 14 to rise. A
second switch 50, which may be placed upon one of the uprights,
such as upright 4 as shown, operates to shut off motor 24. The
switch 50 may either be manually operated or it may be
automatically operated through arm 51 extending above th platform
side 16. Thus, as the lift is set in motion by actuation of switch
49, platform 14 will continue to rise until upright arm 51 actuates
switch 50 to turn the motor 24 off.
As previously mentioned, the platform 14 will neither ascend nor
descend due to its own weight because of the counterweight system.
Th inclusion of passengers or goods will, however, upset this
balance. The gearing arrangement used by the combination of pulleys
and sprockets is designed such that in order for there to be
movement of the platform 14, the armature of motor 24 must turn at
a relatively high rate. This requirement, plus the inherent
frictional resistance present in the lift insures that after the
power to the motor 24 is turned off, the platform 14 descends
relatively slowly. To lock the platform 14 at any given position, a
brake may be utilized. This brake may be desired when motor 24 is
shut off and the platform 14 is in its raised position. Thereby,
the platform 14 will not suddenly or unexpectedly begin to descend
during the loading or unloading operation. The design of the brake
may be quite elaborate if desired or may be a simple go/no-go type
of system. A simple but satisfactory brake system will be
described. A brake shaft 52 may be journalled at 53 on diagonal
support 7 and at 54 on horizontal support 5. One end of the shaft
52 includes a brake shoe arrangement 57, which under pressure of
springs 55, 56, exerts a force upon the edges of pulley 39, thus
retarding or inhibiting rotation of the pulley. The other end of
the shaft 52 may include a horizontally projecting extension 59
riding upon a cam or inclined plane 77 such that if the shaft 52
rotated within journals 53, 54, the horizontal extension 59 rides
up the inclined plane 77 and releases the brake shoe 57 from the
pulley 39. A handle 58 may be connected to extension 59 for ease in
operating the brake. The effectiveness of the brake may be
increased by aligning the shaft 52 off center of pulley 39 and
counter to the expected direction of rotation. Thereby, any
rotation of pulley 39 resulting from the load placed on platform 14
will tend to force the brake shoe 57 upwardly and increase the
force of the brake shoe 57 on the edge of pulley 39.
In operation, an occupant of the lift would utilize the brake in
the following manner. Upon reaching the higher elevation after the
motor 24 is shut off through actuation of switch 50 by arm 51 and
platform 14, the lift will stop. At this time, the occupant would
be within easy reach of handle 58, and could then swing or rotate
th handle 58 such that extension 59 interacted with the inclined
plane 77 to set the brake shoe 57 on the edge of pulley 39. The
platform 14 would then be immobile for all practical purposes and
the occupant could leave the platform 14 without fear of it
suddenly beginning to descend due to his weight. On re-entering the
lift at the raised position, the occupant would begin his descent
by simply rotating handle 58 so as to release the brake shoe 57
from contact with the edge of pulley 39 and calmly await descent of
the platform 14.
As previously mentioned, the sheet material 9, 10, and 11
collectively act to create a barrier about the sides of the
platform 14. A primary purpose of this barrier is to prevent pets,
small children, or other things from crawling under or being placed
beneath the platform 14 while the platform 14 is in the raised
position. Subsequent descent by the platform 14 could conceivably
cause irreparable damage to these children, pets, or other things.
In order to provide a four-sided barrier, a fourth side may be used
which is actuated by movement of the platform 14 itself.
Referring to FIG. 3, a flap 60, pivotally mounted at 68 coincident
with the front edge of the fourth side of base 73 is spring-biased
by spring 61 suitably attached at point 62 to either the base 73 or
a portion of the base framework such that the flap 60 in its normal
position lies horizontally and will not impinge upon or impede the
movement of the platform 14. When the platform 14 is raised, a cord
69 attached to the flap 60 and a fixed point 67 on the raised side
15 of the platform 14 causes flap 60 to pivot into an upright
position. The point of attachment 70 between the cord 69 and the
flap 60 must, of course, be predetermined from the known height to
which the platform 14 rises in order that the flap 60 obtain a
vertical position at the apex of the platform 14 ascent. Thus,
while the platform 14 is in the raised position, the base 73 of the
lift framework is surrounded on all four sides by a barrier whereby
foreign objects cannot be inadvertently or by design be placed
beneath the platform 14. On descent, the flap 60 pivotally swings
out of the way under force of spring 61 so that it will not
interfere with the egress of the occupant from the platform 14.
As a further safety precaution, an enclosure 71, shown in cutaway
view in FIG. 1, may be placed about the counterweight, motor,
pulleys, and sprockets. Similarly, a second enclosure 72 may house
the counterweight and sprockets on the opposite side of the lift
framework.
* * * * *