U.S. patent application number 12/483825 was filed with the patent office on 2009-10-08 for steering and driving systems and related vehicles.
Invention is credited to Hans Hauser.
Application Number | 20090250270 12/483825 |
Document ID | / |
Family ID | 26937036 |
Filed Date | 2009-10-08 |
United States Patent
Application |
20090250270 |
Kind Code |
A1 |
Hauser; Hans |
October 8, 2009 |
Steering and Driving Systems and Related Vehicles
Abstract
A ZTR vehicle includes true or proper ZTR steering in the
forward and reverse directions. The vehicle has independently
driven locomotive drives that drive the wheels to provide mobility
and steering to the vehicle. A steering wheel is included that
pivots one of two steering input members that rotate to
independently shift the drive units. A speed and direction pedal is
also included, which is communicated to provide direction and
magnitude input to the drive units. The steering input and speed
and direction inputs coordinate propelling the vehicle such the
vehicle turns in the same direction when traveling forward as well
as in reverse.
Inventors: |
Hauser; Hans; (Strongsville,
OH) |
Correspondence
Address: |
FULBRIGHT & JAWORSKI L.L.P.
600 CONGRESS AVE., SUITE 2400
AUSTIN
TX
78701
US
|
Family ID: |
26937036 |
Appl. No.: |
12/483825 |
Filed: |
June 12, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11269899 |
Nov 8, 2005 |
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12483825 |
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10245158 |
Sep 11, 2002 |
6962219 |
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11269899 |
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60322943 |
Sep 17, 2001 |
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Current U.S.
Class: |
180/6.32 ;
180/315 |
Current CPC
Class: |
B62D 11/04 20130101;
B62D 11/006 20130101 |
Class at
Publication: |
180/6.32 ;
180/315 |
International
Class: |
B62D 11/02 20060101
B62D011/02; B60K 26/00 20060101 B60K026/00 |
Claims
1. A steering and drive control mechanism for a zero turn radius
vehicle that includes a vehicle chassis and a pair of transmission
systems for independently driving at least two traction elements
that are spaced from each other and each define two parallel drive
directions for driving said vehicle, said steering and drive
control mechanism comprising a drive assembly comprising a pivoting
member mounted to pivot about a pivot axis relative said chassis, a
pair of control linkage members engaged to the pivoting member in a
movable manner so that the connection point for each control
linkage member with said pivoting member can be moved relative said
pivot axis, each said control linkage member in operative
connection with a respective transmission systems to control the
respective transmission system, a foot operated pedal assembly,
operatively coupled to the drive assembly so that movement of the
pedal assembly results in pivotal movement of the pivoting member
about the pivot axis; a steering member pivotally connected to the
vehicle chassis, a steering assembly coupling the steering member
with the control linkage members so that pivoting movement of the
steering member can vary the position of one or both of the
connection points of the control linkage members relative the pivot
axis to thereby effect a change in operation of one of both of the
transmission systems.
2. The steering and drive control mechanism as claimed in claim 1
wherein the location of each of the connection points at the
pivoting member of each of the control linkage members can be
varied by independently.
3. The steering and drive control mechanism as claimed in claim 1
wherein biasing means is provided to bias the control linkage
members to a location relative the pivoting member where the
location of the connection points in the same distance from the
pivot axis.
4. The steering and drive control mechanism as claimed in claim 1
wherein each said control linkage member is mounted relative said
chassis by a mount that allow the control linkage member to
displace in a manner rotationally unconstrained by said mount upon
(a) the rotation of said pivoting member about the pivot axis
and/or (b) movement of the steering member to vary the position of
one or both of the connection points of the control linkage members
relative the pivot axis.
5. The steering and drive control mechanism as claimed in claim 1
wherein the traction elements be wheels.
6. The zero turning radius lawnmower that includes the mechanism as
claimed in claim 1.
7. The zero turning radius lawnmower, said lawnmower comprising a
pair of transmissions to drive at least two drivers independently
of each other; a chassis; a steering and drive control mechanism as
claimed in claim 1.
8. The lawnmower as claimed in claim 7 wherein the steering member
is a steering wheel.
9. A control mechanism to control the speed and direction of travel
of a vehicle that includes a steering wheel and an accelerator
pedal, said vehicle capable of being propelled by two spaced apart
traction elements each independently driven by a respective motor,
the output torque of each motor controlled by a displaceable input
device, said control mechanism comprising; a first push-pull rod
having a first distal end and a second distal end, said first
distal end engaged to said input device of one of said motors
(hereinafter "first motor"), a second push-pull rod having a first
distal end and a second distal end, said first distal end engaged
to said input device of the other of said motors (hereinafter
"second motor"), a pivot member mounted from said vehicle pivotable
about a pivot axis in a manner responsive to the position of the
accelerator pedal, said pivot member including at least one lever
arm to which and along at least part of which at least one of said
first and push-pull rod members and second push-pull rod members
can traverse by being slidingly coupled thereto at or towards said
second distal end, such that when said pivot member is pivoted
about pivot axis, the first push-pull rod can, when in at least one
position along said lever arm, displace the input device of said
first motor and said second push-pull rod can, when in at least one
position along said lever arm, displace the input device of said
second motor, a first coupling member operatively extending between
said steering wheel and said first push-pull rod and a second
coupling member operatively extending between said steering wheel
and said second push-pull rod, wherein the movement of said
steering wheel is, via said coupling members, capable of displacing
both said first push-pull rod and said second push-pull rod along
said lever arm to displace first push-pull rod and/or said second
push-pull rod relative said pivot axis to thereby change the
effective lever arm effect of said pivot member on said first
push-pull rod and/or said second push-pull rod and thereby vary its
effect on its respective input device.
10. The mechanism as claimed in claim 9 wherein the pivot member
includes two lever arms, one for each of said first push-pull rod
and said second push-pull rod, each said lever arm movable in
unison.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] The present application is a continuation of co-pending U.S.
patent application Ser. No. 11/269,899, filed Nov. 8, 2005 which is
a continuation of U.S. patent application Ser. No. 10/245,158,
filed Sep. 11, 2002, now issued as U.S. Pat. No. 6,962,219, which
claims priority to U.S. Provisional Application Ser. No.
60/322,943, filed on Sep. 17, 2001. U.S. patent application Ser.
Nos. 10/245,158 and 11/269,899 are incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] A. Field of Invention
[0003] The present invention relates to the art of Zero Turn Radius
vehicles and more specifically to Zero Turn Radius mowers
incorporating mechanical steering systems.
[0004] B. Description of the Related Art
[0005] Zero Turn Radius (ZTR) vehicles including mowers work well
for their intended purpose. One advantage of ZTR vehicles is that
they are capable of making very tight (zero radius) turns. One
disadvantage of most ZTR vehicles is that their operation is not
intuitive for most operators because steering of the vehicles is
accomplished by steering levers, rather than a steering wheel.
Recently, steering wheels have been incorporated onto ZTR vehicles.
However, known ZTR vehicles using a steering wheel steer the
vehicle differently in the forward direction of travel than in
reverse. That is to say, that with the steering wheel steered to
turn the vehicle right, and upon depressing the accelerator, the
vehicle will make a forward right turn. But, when the accelerator
is depressed to drive the vehicle in reverse, the vehicle makes a
rearward left turn, rather than a rearward right turn. What is
needed is a reliable mechanical ZTR steering system that steers the
vehicle consistently in the direction that the steering wheel is
turned in forward as well as the reverse directions.
[0006] Other objects and advantages of the invention will appear
from the following detailed description of the preferred embodiment
of the invention with reference being made to the accompanying
drawings.
BRIEF SUMMARY
[0007] The present invention includes a ZTR vehicle that provides
for proper steering of the ZTR vehicle in the forward and reverse
directions.
[0008] Another aspect of the present invention includes a ZTR
vehicle having a steering wheel that controls the steering of the
vehicle.
[0009] Yet another aspect of the present invention includes
hydrostatic drives that drive each respective rear ground engaging
wheel independently from the other.
[0010] Still another aspect of the present invention includes an
asynchronously actuated set of two steering input members that
engage the hydrostatic drives.
[0011] Still yet another aspect of the present invention includes a
speed and direction input member that maneuvers pintle links of the
hydrostatic drive substantially in unison.
[0012] A ZTR vehicle is provided that steers the same in the
forward and reverse directions. The vehicle includes a steering
wheel operatively connected to independently steer two (2) drive
control members. The drive control members provide input to two (2)
locomotive drive units that propel and steer the vehicle. An
accelerator pedal or speed input device is rotatably disposed about
the vehicle to provide speed and direction input to drive the
vehicle. The accelerator pedal is connected to a rotating shaft
that pivots two (2) speed input members. The steering wheel
provides steering input to two (2) steering input members. The
steering input members each have sleeves that slide longitudinally
about the drive control members to provide independent shifting of
the drive control members in the forward and reverse
directions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention may take physical form in certain parts and
arrangement of parts, a preferred embodiment of which will be
described in detail in this specification and illustrated in the
accompanying drawings which form a part hereof and wherein:
[0014] FIG. 1 is a side view of a ZTR vehicle.
[0015] FIG. 2 is a partial cutaway view of the power train of the
ZTR vehicle, including Hydrostatic Drives.
[0016] FIG. 3 is a top view of the mechanical ZTR control
linkage.
[0017] FIG. 4 is a close up side view of the mechanical ZTR control
linkage.
[0018] FIG. 5 is a perspective view of the steering wheel and
steering mechanism.
[0019] FIG. 6a is a schematic side view of the ZTR control assembly
with no steering input and no speed input.
[0020] FIG. 6b is a schematic side view of the ZTR control assembly
with no steering input and speed input driving the vehicle in a
forward direction.
[0021] FIG. 6c is a schematic side view of the ZTR control assembly
with no steering input and speed input driving the vehicle in a
reverse direction.
[0022] FIG. 7a is a schematic side view of the ZTR control assembly
with the steering wheel fully turned and no speed input.
[0023] FIG. 7b is a schematic side view of the ZTR control assembly
with the steering wheel fully turned and speed input actuated to
drive the vehicle in forward direction resulting in a forward ZTR
turn.
[0024] FIG. 7c is a schematic side view of the ZTR control assembly
with the steering wheel fully tuned and speed input actuated to
drive the vehicle in reverse direction resulting in a reverse ZTR
turn.
[0025] FIG. 8 is schematic representation of the drive control
members and the speed input members engaged in the forward
direction.
[0026] FIG. 9 is schematic representation of the drive control
members and the speed input members engaged in the reverse
direction.
[0027] FIG. 10 is schematic representation of the drive control
members and a series of trajectories for the control members.
[0028] FIG. 11a is schematic representation of the drive control
members and the speed input members engaged in the forward
direction.
[0029] FIG. 11b is schematic representation of the drive control
members and the speed input members engaged in the forward
direction.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0030] Referring now to the drawings wherein the showings are for
purposes of illustrating a preferred embodiment of the invention
only and not for purposes of limiting the same, FIG. 1 depicts a
ZTR vehicle 1. The ZTR vehicle 1 includes a frame 3 supporting two
rotatably-mounted front ground engaging wheels 4, 5 and two
rotatably-mounted rear ground engaging wheels 6, 7. The rear ground
engaging wheels 6, 7 provide steering and mobility to maneuver the
vehicle 1 as desired. The vehicle 1 may include an engine 7, which
may be an internal combustion engine 8. However, any type of engine
may be chosen with sound engineering judgment that provides power
to operate the vehicle 1. The vehicle 1 may also include a steering
wheel 10 that is operatively connected to steer the vehicle 1 as
will be discussed in greater detail in a subsequent paragraph. A
speed control member 11 may be rotatably attached to the vehicle 1,
which is operable to provide variable speed control input in first
and second directions, as will be discussed subsequently.
Additionally, the ZTR vehicle 1 may include a mower deck 13 wherein
the ZTR vehicle 1 is a ZTR mower 2.
[0031] With reference now to FIG. 2, a pair of locomotive drive
units, 16, 18 are shown operatively connected to drive rear ground
engaging wheels 6, 7 respectively. In the preferred embodiment, the
drive units 16, 18 are hydrostatic drives (HDs) but it is to be
understood that other drive units are also contemplated, such
electric and mechanical drive units. The drive units 16, 18 are
used to independently drive the rear wheels 6, 7 as is well known
for ZTR vehicles and which will not be discussed further. The
hydrostatic drives 16, 18 may include pivotally attached pintle
links 22, 24 that when pivoted in first and second directions
control power that drives the respective wheels in first and second
directions. The more that the pintle links 22, 24 are pivoted, the
greater the magnitude of speed that the locomotive drives 16, 18
are driven in each respective direction. First ends 26a, 28a of
input shafts 26, 28 may be connected to the pintle links 22, 24
respectively and may translate tension and compression forces for
use in pivoting the pintle links 22, 24 in the first and second
directions. It is noted that the input shafts 26, 28 may be
independently shifted with respect to the other. By "shifted" it is
meant that the input shafts 26, 28 may be separately longitudinally
moved whereby the pintle links 22, 24 are pivoted respectively.
Additionally, the input shafts 26, 28 may be pivotally attached at
the first ends 26a, 28a to the pintle links 22, 24 in such a manner
so as to allow for pivotal movement of the input shafts 26, 28 with
respect to the pintle links 22, 24. In other words, the first ends
26a, 28a of the input shafts 26, 28 may be pivoted with respect to
the pintle links 26, 28.
[0032] With reference now to FIGS. 2 and 3, a ZTR control assembly
is shown generally at 31. The ZTR control assembly 31 includes a
linkage, which in the preferred embodiment may be mechanical
members, interconnected to receive steering input from the steering
wheel 10 and speed control input from the speed control member 11
for use together in providing control to shift the input shafts 26,
28. The speed control member 11 may be a foot pedal or hand lever
for controlling the magnitude and direction of the speed input by
pivoting the member 11. It is noted that any member may be used to
provide speed input as chosen with sound engineering judgment. The
steering wheel 10 may also be exchanged with other steering members
as is appropriate for use with the present invention. The linkage
31 is configured to steer the vehicle the same in the forward as in
the reverse direction. In other words, the ZTR control linkage 31
is interconnected to the steering wheel 10 and the speed control
member 11 to provide proper steering in the reverse and forward
directions of travel. That is to say that when the vehicle is being
driven in a first, or forward, direction and when the steering
wheel 10 is turned in a first steering direction, to the right for
example, the left rear ground engaging wheel will drive faster than
the right rear ground engaging wheel thereby steering the vehicle
in the first direction, or right direction. For true ZTR steering
in this case, the left rear ground-engaging wheel may drive forward
and the right rear ground-engaging wheel may drive backward. When
the vehicle is driven in the reverse, or second, direction, and
with the steering wheel still turned in the first steering
direction, which may be to the right, the left rear ground-engaging
wheel may still drive faster than the right rear ground engaging
wheel accept in the opposite direction causing the vehicle to steer
properly in the forward and reverse direction. By steering properly
in the forward and reverse directions it is meant that the steering
of the ZTR vehicle responds similarly to a vehicle having drive
wheels driven at a constant rate and wherein steering wheels are
pivoted with respect to the frame of the vehicle.
[0033] With continued reference to FIGS. 2 and 3, the ZTR control
linkage 31 may include a rod member 38 that is rotatably attached
with respect to the frame 3. The rod member 38 has a first end 39
that is fixedly attached to a speed control member 11 or pedal
member 41. The pedal member 41 is therefore also pivotally attached
with respect to the frame 3, which is allowed to rotate in first
and second directions. It is noted the pedal member 41 may be
biased via a spring or other mechanism toward a neutral or
non-driving position. The first direction may represent the forward
direction of travel, which when member 11 is depressed will drive
the vehicle forward. With the steering wheel not steered in a first
or second direction, the drive units will drive equally at the same
magnitude propelling the vehicle straight forward, not steering in
either direction. Likewise, the second or reverse direction
functions in a similar manner. In this way, depressing the pedal
member 41 in a first direction rotates the rod member 38 in a first
rotational direction 42 and likewise depressing the pedal member 41
in a second direction rotates the rod member 38 in a second
rotational direction 43. There is also fixedly attached to the rod
member 38 two control members 34, 35, which may be two speed input
members 54, 55. However, in that the two members 34, 35 rotate
together in unison, the two control members 34, 35 may function as
a single speed-control member 34a. In this way, actuation of the
pedal member 41 applies rotational force equally to both of the
speed input members 54, 55. The speed input members 54, 55 will be
discussed in greater detail in a subsequent paragraph. The ZTR
control assembly 31 may also include two second members 44, 45,
which may be steering input members 64, 65. The steering members
64, 65, at a first end 64a, 65a thereof, are received onto the rod
member 38 in such a manner that the steering members 64, 65 may
rotate with respect to the rod member 38. In this way, depressing
the pedal member 41 in either direction does not affect the
rotational movement or adjustment of the steering members 64, 65.
Additionally, there may be two generally tubular sleeve members 51,
52 that are rotationally attached with respect to second ends 64b,
65b of the steering members 64, 65. The sleeve members 51, 52 are
also respectively received onto the input shafts 26, 28 and may
slide longitudinally thereon for use in providing input steering
forces as will be discussed in a subsequent paragraph. As the
steering members 64, 65 are rotated, the sleeve members 64, 65 may
independently rotate with respect to the first ends 64a, 65a of the
steering members 64, 65 and will further be longitudinally adjusted
along the input shafts 26, 28.
[0034] With reference now to FIGS. 3 and 4, FIG. 4 depicts a close
up side view of only one section of the mechanical ZTR control
linkage 31 for the purpose of clarity. It is understood that the
opposite side of the linkage functions in a similar manner. The rod
member 38 has a U-shaped portion 38a whereon the speed input
members 54, 55 are fixedly attached. The speed input members 54, 55
may have an aperture 36 fashioned therein that receives the rod
member 38. Subsequently, the speed input members 54, 55 may be
welded to the rod member 38a. However, any configuration of the
speed input member and any means of fixedly securing the speed
input members 54, 55 to the rod member 38a may be chosen with sound
engineering judgment. It is noted that FIG. 4 shows the cross
section of the U-shaped portion 38a of the rod member 38 disposed
in the plane of the speed input members 54, 55. Likewise, FIG. 4
shows the cross section of the rod member 38 in the plane of the
steering members 64, 65 at the first end 64a, 65a of the steering
members 64, 65. Focusing on the input shafts 26, 28, the second
ends 26b, 28b are fashioned to form slot pins 58, 59. The slot pins
58, 59 are curved so as to engage a slot 37 formed in the speed
input members 54, 55 as will be discussed in the following
paragraphs. In this manner, the slot pins 58, 59 are fashioned to
sliding engage the speed input members 54, 55 along the length of
the slot 37 formed in the speed input members 54, 55. When the
steering input 54, 55 are rotated in a first direction, the input
shafts 26, 28 may be pulled or shifted in a first direction
rotating the pintle links and engaging the driving units.
[0035] With continued reference to FIG. 4 and now to FIG. 5, the
steering wheel 10 may be fixedly connected to a pinion gear 70 that
meshingly engages a steering disk 72 having coordinating gear teeth
73. At a distal end 75 of the steering disk 72, the steering disk
72 is pivotally attached with respect to the frame 3. In this
manner, turning the steering wheel 10 rotates the pinion gear 70
that in turn rotates the steering disk 72. In that the operation of
steering wheels and steering mechanisms are well known, no further
explanation will be offered at this point. First and second tension
cables 77, 78 are further included and fixedly attach at first ends
77a, 78a to the steering disk 72, as clearly shown in Figures, and
at second ends 77b, 78b to the steering members 64, 65. It is noted
that the tension cables 77, 78 translate tension force only. In
this way, rotating the steering wheel 10 applies force to only one
of the tension cables 77, 78 at a time. In other words, rotating
the steering wheel 10 in a first direction applies tension force to
tension cable 77, while allowing tension cable 78 to be slack or be
in a state having no tension applied to the cable. Consequently,
rotating the steering wheel 10 in the second direction applies
tension force to cable 78, while allowing cable 77 to be slack. In
this manner, rotating the steering wheel 10 applies tension force
to one of the steering member 64, 65. It is noted that the steering
members 64, 65 may be biased toward a default position by any means
chosen with sound engineering judgment. In this way, the steering
member 64, 65 may be preloaded with predetermined amount of force,
taking up slack in the cables 77, 78 during rotation of the
steering wheel 10.
[0036] With continued reference to FIGS. 2 through 5 and now to
FIGS. 6 and 7, the operation of the present invention will now be
discussed. FIGS. 6 and 7 schematically show the various positions
of the steering members 64, 65, the speed input members 54, 55 and
the input shafts 26, 28 as related to steering and accelerating the
vehicle 1. Specifically, FIG. 6 refers to a first mode of operation
where the vehicle 1 is driving straight, that is to say that the
vehicle 1 is being driven forward without steering input. In this
mode, the driver depresses the pedal member 41 (Reference FIG. 3)
in a first direction 42, which causes rotation of the speed input
members 54, 55. This is clearly depicted in FIG. 6b. As previously
described, this action results in the pintle links 22, 24 being
shifted, which drives the vehicle 1 forward. It is noted that the
steering members 64, 65 remain in a constant default position,
which forces the slot pins 58, 59 toward one end 37a of the slot
37. In a similar manner, depressing the pedal member 41 in the
second direction 43 drives the vehicle 1 in reverse. Referring now
to FIG. 7, FIG. 7a shows the steering wheel 10 rotated in a first
direction to a maximum position. In this manner, the tension cable
77 applies force to rotate steering member 64, whereby the bias
force holding the steering member 64 is overcome. This shifts slot
pin 58 to a distal end of slot 37. In this manner, depressing the
pedal member 41 in a first direction causes rotation of pintle link
22 in a reverse direction than when slot pin 58 was biased in the
default position. In other words, depressing the pedal member 41 to
drive the vehicle forward, with the steering wheel 10 fully turned
in the first direction, causes pintle link 22 to drive that
respective wheel in reverse. Noting that the opposing wheel is
driven forward, this results in a Zero Radius turn. Thus, it can be
seen that ZTR steering in forward and reverse is accomplished. It
is noted that the vehicle 1 may include front steerable wheels 4, 5
that are rotated proportionately to the turning radius of the
vehicle. Any manner of steering the front wheels 4, 5 may be chosen
with sound engineering judgment. In this way, the front steerable
wheels 4, 5 may be rotated to be substantially tangent to an arc
defined at one point by the radius of turning and by the other
point at the center of each wheel 4, 5.
[0037] With reference again to FIG. 4 and now to FIGS. 8 and 9, the
shifting of the input shafts 26, 28 will now be discussed. As
previously mentioned, the input shafts 26, 28 may be rigid rods
connected at respective first ends 26a, 28a to the pintle links 22,
24, reference FIG. 2. The pintle links 22, 24, as well known in the
art, actuate the drive units, or stroke the hydrostatic drive, in
first and second directions and at selectively varying magnitudes
of speed. The distal ends of the input shafts 26, 28, or drive
control members, may be communicated to the speed input members 54,
55 and the steering members 64, 65 as previously described. FIG. 8
shows only one of the speed input members 54, 55 and one drive
control member or input shaft 26, 28 for clarity. The drive control
member 26, 28 may have a neutral or non-engaging position N wherein
the respective locomotive drive 16, 18 is substantially not engaged
to drive in either the forward or reverse direction. The drive
control member 26, 28 is shown received in the slot 37 of the speed
control member 54, 55 at a top position 37a. This may be the
default or biased position. When the pedal member 41 is rotated in
a first direction 42, the drive control member 26, 28 is shifted in
a first direction to engage the respective locomotive drive unit
16, 18 to drive in a first direction and speed. Similarly, FIG. 9
shows the same shifted in a second direction. The first direction
42 may coordinate with a forward direction of travel and second
direction 43 may coordinate with the reverse direction of travel.
However, any configuration of engaging the drive units 16, 18 and
shifting the control members 26, 28 may be chosen with sound
engineering judgment.
[0038] It can be observed from FIGS. 8 and 9, that the drive
control members 26, 28 may be adjusted through the slot 37 applying
a force F to overcome the bias force, which may be a spring force
not shown, operatively connected in a manner well known in the art.
In the preferred embodiment, the force F may be applied via the
slidably engaging steering members 64, 65 actuated by selectively
steering the steering wheel 10, which will be discussed further in
a subsequent paragraph. Continuing, the drive control members 26,
28 may selectively pivot through the slot 37 to cross from a first
direction 42 position through the neutral position N to a second
direction position 43. The speed input members 54, 55 may be
rotated, in an analog fashion, at any point from a first maximum
position 42a to a second maximum position 43a establishing a series
or a plurality of trajectories through which the drive control
members 26, 28 may be selectively maneuvered. FIG. 10 shows one
such series of trajectories. In this manner, the drive control
members 26, 28 may be selectively shifted from a top or upper slot
position to a lower or bottom slot position. However, it is
expressly noted that pivoting from the top to the bottom position
may shift the respective drive control member 26, 28 from the first
direction 42 to the second 43 or from the second direction 43 to
the first 42 depending upon the position of the speed control
members 54, 55. It is also noted that the top and bottom positions
of slot 37 may be selectively positioned at various points between
the first and second maximum positions 42a, 43a. In this way, as
the speed input members 54, 55 shift both of the drive control
members 26, 28 in unison and in that the steering members 64, 65
can be rotated independently or asynchronously, it can be seen that
the shifting of the drive control members 26, 28 may resultantly
actuate the locomotive drives 16, 18 to steer and propel the ZTR
vehicle 1 in a manner consistent with proper steering in the
forward and reverse directions.
[0039] With reference now to FIGS. 11a and 11b, the drive control
members 26, 28 are shown steered in a first direction and driven in
a first direction 42. For purposes of clarity, the steering members
64, 65 are replaced with force vectors F1 to show the operation of
the present invention more clearly. It should be noted that the
present configuration is representative of FIG. 7c. In this case,
the tension cable 77, which may also be rigid rod members
configured to translate tension force only, pull on the first
rotatable steering members 64, overcoming bias forces, thereby
rotating the steering member 64 in a first direction, which may be
clockwise. Since the opposing cable 78 is not under tension, no
steering force is supplied to the steering member 65, although the
steering member 65 may include a force means to bias the steering
member 65 substantially in a second direction, which may be a
counter clockwise direction. In this manner, the drive control
members 26, 28 may be shifted asynchronously. FIG. 11a shows the
drive control member 26 shifted a distance X in the first direction
and shows drive control member 28 shifted in the second direction a
distance Y. It is noted that the slot 37 may be slightly curved to
compensate for differences in actuating the locomotive drives 16,
18 due to hysteresis and other non-linear factors. However, any
configuration of slot 37 fashioned in the speed control members 54,
55 may be chosen with sound engineering judgment. Distance X may be
greater than distance Y, representing that drive 16 has a greater
magnitude of speed than drive 18. In that the directions are
opposite, the first wheel 6 may be rotating forward at a speed
proportionate to distance X and the second wheel 7 may be rotating
in reverse at a speed proportionate to distance Y, thus resulting
in a turning radius that resides within the wheelbase or at the
center of the wheelbase. When the pedal member 41 is pivoted in the
second direction 43 and with the steering in the same position,
that is to say that forces F and F1 remain constant, the magnitude
of the ratio of XJY remains the same although the direction of each
drive is reversed. This results in proper steering in the forward
and reverse directions as previously mentioned.
[0040] While specific embodiments of the invention have been
described and illustrated, it is to be understood that these
embodiments are provided by way of example only and that the
invention is not to be construed as being limited thereto but only
by proper scope of the following claims.
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