All terrain vehicle for disabled persons

A self-powered, all terrain vehicle designed for self-assisted transfers of a paraplegic, or other disabled person, between the vehicle and a wheelchair. A longitudinally extended vehicle underframe is carried between two track mechanisms. Each track mechanism has an endless belt about the same and about pivotally mounted idler wheels and a rear drive sprocket in driving engagement with the belt. Each drive sprocket is driven by a hydraulic motor powered by a hydraulic pump coupled to an internal combustion engine. Height adjustable motor mounts permit adjusting the tension in each belt. A seat assembly carried by the underframe provides a passenger seating surface that extends laterally outward over the track mechanisms to minimize the lateral distance a wheelchair-bound passenger must heave his body to mount and dismount the vehicle. To achieve a narrow vehicle profile for ease of passenger entry and exit, the engine and hydraulic drive system components are disposed longitudinally, and the hydraulic fluid tank comprises two wing tank portions disposed under side portions of the seating surface and joined by a rear tank portion mounted behind the seating assembly. An air bladder seat suspension system aids passenger comfort and permits adjusting the longitudinal attitude of the seating surface. Passenger safety restraints include a pair of leg rests, and seat and shoulder belts. A steerable auxiliary wheel system is provided for rolling the vehicle on auxiliary wheels in the event the vehicle becomes inoperable.

CROSS REFERENCE TO RELATED APPLICATIONS 
Not applicable. 
STATEMENT REGARDING FEDERALLY APPROVED RESEARCH OR DEVELOPMENT 
Not applicable. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to small, self-propelled vehicles that may be used 
by the infirm, disabled or aged, and particularly to a personal, 
all-terrain vehicle for transporting a paraplegic. 
2. Background Art 
Self-propelled wheelchairs have been used by aged and infirm persons for 
personal transportation, commonly powered by an electric battery and 
motor, but an internal combustion engine powered version was also 
disclosed by Walker, U.S. Pat. No. 4,475,613. Wheelchairs are generally 
suitable, however, only for locomotion over smooth or paved surfaces. For 
self-propelled transportation over rough and uneven terrain such as 
stairs, mountain and forest trails, and gravel roads, vehicles mounted on 
a pair of tracks or endless belts, and a passenger seat mounted on the 
vehicle between the tracks, have been developed. See, for example, the 
tracked stair climbing wheelchair described by Littlejohn, et al., U.S. 
Pat. No. 5,123,495, and that described by Watkins, U.S. Pat. No. 
4,674,584. Such tracked vehicles can be ideal for outdoor use in rugged, 
hilly terrain because their dual track mechanisms can provide a stable, 
wide stance, and excellent ability to grip loose and muddy surfaces, and 
uneven surfaces. Heretofore, however, the task of boarding and unboarding 
the tracked vehicle has been difficult for wheelchair-bound persons, 
especially during self-assisted transfers executed by paraplegics. When 
the wheelchair would be drawn up alongside and parallel to one of the 
track mechanisms and adjacent the passenger seat of the tracked vehicle, 
it would be necessary to lift and swing the entire lower body of the 
paraplegic up and out of the wheelchair, all the way across one track 
mechanism, and into the passenger seat. Self-assisted transfer from the 
tracked vehicle back to the wheelchair was equally difficult due to the 
width of the track mechanisms. Thus, there remains a need for a tracked, 
stable, self-propelled all-terrain vehicle designed for self-assisted 
transfers from and to a wheelchair. 
SUMMARY OF THE INVENTION 
The present invention provides a self-propelled, all-terrain vehicle for 
self-assisted transfers of a disabled person (e.g., a paraplegic) between 
the vehicle and a wheelchair, and for transporting the person over a 
ground surface. The vehicle has a longitudinally elongated underframe 
carried between left and right tracks mechanisms. Each of the track 
mechanisms has an endless belt about the mechanism, pivotally mounted 
idler wheels, and a rear drive sprocket in driving engagement with the 
belt. 
A seat assembly is centrally disposed above and carried by the underframe 
at a height above the surface substantially equal to the height of the 
seat of a wheelchair. The seat assembly includes a horizontal seat panel 
having front and rear edges and left and right side portions joining the 
front and rear edges. In order to minimize the lateral distance over which 
a disabled person seated in a wheelchair adjacent one side of the vehicle 
must swing his body and legs in order to sit in the vehicle, the side 
portions of the seat panel extend laterally over, and only slightly above, 
each of the track mechanisms. This arrangement likewise minimizes the 
distance over which a disabled person seated in the vehicle must swing his 
body and legs in order to dismount from the vehicle into his wheelchair. 
The vehicle is provided with hydraulic drive means, including left and 
right hydraulic motors coupled to the left and right drive sprockets, each 
motor supported by a motor mount assembly attached to the underframe. The 
vehicle is powered by an internal combustion engine mounted on the 
vehicle, which drives a hydraulic fluid pump. Hydraulic drive control 
means is provided for initiating and controlling forward, reverse, and 
turning movements of the vehicle by controlling the flow of pressurized 
fluid from the pump to the hydraulic motors. In an alternative embodiment, 
however, the internal combustion engine instead drives a direct current 
electric generator, the electric power output of which is conducted 
through a voltage regulator to electric storage batteries. An electric 
motor wired to the batteries drives the hydraulic fluid pump. 
A hydraulic fluid storage tank is provided having left and right wing tank 
portions under the left and right side portions of the seat panel, 
respectively, and a rear tank portion disposed adjacent the rear edge of 
the seat panel and in communication with the wing tank portions. Both the 
wing tank portions and the rear tank portion are mounted to the seat 
assembly above the height of the track mechanisms, thereby helping to 
minimize the distance between the track mechanisms. Preferably, each wing 
tank portion is substantially triangular in longitudinal cross-section, 
having a pair of substantially triangular side walls joined by a 
horizontal top wall, and a forwardly and downwardly sloping bottom wall. 
One of the wing tank portions is provided with an exit port 159 for 
delivering hydraulic fluid to the hydraulic drive means; the opposite wing 
tank portion has a return port for receiving hydraulic fluid from the 
hydraulic fluid drive means. A fuel tank is mounted on the vehicle and 
disposed above the rear tank portion of the hydraulic fluid tank. 
Preferably, the fuel tank is integral with the hydraulic fluid rear tank 
portion and has a bottom wall that is also a top wall of the rear tank 
portion. 
The vehicle has an underframe, including left and right inner rails, each 
inner rail having a front end and a rear end. A front cross member joins 
the inner rail front ends; a rear cross member joins the inner rail rear 
ends. A rear skid plate is attached to and joins a rear portion of each of 
the inner rails, and extends forward from the rear cross member to a 
central portion of the underframe. A horizontal front skid plate is 
attached to and joins a front portion of each of the inner rails, and 
extends rearward from the front cross member to the rear plate. 
The seat assembly includes left and right pairs of equal-length, 
spaced-apart vertical seat supports. Each seat support has a lower end 
attached to the rear plate and an opposite, upper end. The upper ends of 
the left and right pairs are attached to left and right side portions of 
the seat frame lateral supports, respectively. The seat assembly further 
includes an arm rest assembly. The arm rest assembly has left and right 
pairs of equal-length, spaced-apart vertical arm rest supports. Each arm 
rest support has a lower end attached to the seat frame and an opposite, 
upper end. The arm rest assembly further includes left and right, arm 
rests extending between the left and right pairs of vertical arm rest 
supports, respectively. At least one of the arm rests is removable to 
facilitate entry to and exit from the vehicle. The arm rest assembly also 
includes left and right back supports, each back support having a lower 
end attached to the seat frame and an opposite free end; a seat cushion 
that rests upon the seat panel 92; and a back cushion attached to the back 
supports. Safety restraints are provided, including seat and lap restraint 
belts, and a pair of removable leg rests. 
The motor mount assembly permits adjustment of the height of the hydraulic 
motors and attached rear sprockets with respect to the underframe, which 
provides a means for adjusting the tension of the endless belts. 
Accordingly, the motor mount assembly comprises upstanding, apertured, 
left and right motor mount lugs attached to a rear portion of the 
underframe, and left and right motor mounts. Each motor mount includes a 
lower bracket portion attached to a motor mount lug and has a vertical 
height adjustment slot. Integral with the lower bracket portion and 
extending upward therefrom, is an upper bracket portion having first, 
second and third apertures for receiving the shaft, forward drive port, 
and reverse drive port of a hydraulic motor, respectively. The upper 
bracket portion is adapted for supporting a hydraulic motor with the shaft 
thereof oriented laterally outward of the underframe. Each motor mount 
further includes a height adjustment bolt inserted through each motor 
mount lug and through the height adjustment slot of the motor mount 
attached thereto. Each height adjustment bolt is fitted with a wing nut 
for securing the motor mount at a desired height. The motor mount assembly 
also includes a laterally disposed, horizontal tie bar that extends from 
the lower bracket portion of the right motor mount to the lower bracket 
portion of the left motor mount and is attached to each lower bracket 
portion. 
Each track mechanism includes an outer rail; the outer rails are attached 
to opposite sides of the underframe. A large front idler is rotataby 
mounted between front portions of the each of the outer rails and the 
underframe; likwise, a large rear idler is rotatably mounted beween rear 
portions of each of the outer rails and the underframe. Two pairs of 
longitudinally spaced-apart, small idler wheels are disposed in tandem 
between central portions of the support members and between each of the 
large front and rear idler wheels. Means are provided for spring coupling 
to the outer rails and the underframe each large front idler wheel, each 
large rear idler wheel, and each pair of small idler wheels. 
In an alternative embodiment, the seat panel is eliminated and the seat 
assembly instead includes a seat suspension system that rests on the seat 
frame. The seat suspension system includes parallel upper and lower air 
bladder support plates and a plurality of horizontally spaced-apart, 
inflatable air bladders resting upon and attached to an upper surface of 
the lower air bladder support plate, and attached to a lower surface of 
the upper bladder support plate. A seat cushion rests on the upper air 
bladder support plate. The longitudinal pitch of the seat cushion can be 
varied by adjusting the air pressures within the air bladders. 
The vehicle is preferably equipped with a steerable, auxiliary wheel system 
by which the vehicle can be rolled about when the vehicle is otherwise 
inoperable--due to engine failure, for example. This system includes a 
removable steering column and steering column support, which are storable 
separate from the vehicle. When the auxiliary wheel system is to be used, 
the steering column and steering column support are installed into the 
vehicle, as follows: an upper end of the steering column, with attached 
steering wheel, is positioned above the seat surface, and an opposite 
lower end of the column is positioned above the front cross member. The 
steering column support is attached to the seat assembly and in supporting 
engagement with the steering column intermediate the upper and lower ends 
of the column. The auxiliary wheel system also includes left and right 
rear wheel assemblies attached to the rear portions of the left and right 
rails, and left and right front wheel assemblies attached to front 
portions of the left and right rails, respectively. Each of the wheel 
assemblies has auxiliary wheels that are height adjustable between an 
upper, retracted position and a lower, surface-engaging position. A 
steering linkage means is attached to a lower, front portion of the 
vehicle for imparting pivotal motions to each of the front auxiliary 
wheels about a vertical axis through a central portion of each of the 
auxiliary wheels in response to rotational motions of the steering wheel. 
Important objectives of the present invention therefore include the 
following: 
It is an object of the invention to provide a self-propelled, all-terrain 
vehicle, comprising a longitudinally elongated underframe carried between 
left and right track mechanisms, for self-assisted transfers of a disabled 
person between the vehicle and a wheelchair, and for transporting the 
person over a surface. 
It is another object of the invention to power such a vehicle with an 
internal combustion engine driving a hydraulic pump, the pump being 
connected by hydraulic conduit to a hydraulic drive system controlled by 
hydraulic drive control means. 
It is a further object of the invention to provide such a vehicle wherein 
the overall width of the vehicle is minimized by placing the seat and wing 
tank portions of the hydraulic fluid tank partially over the track 
mechanisms instead of between the track mechanisms, and wherein the height 
of the vehicle seat approximates the height of a wheelchair seat, thereby 
reducing the effort that would otherwise be required for a disabled 
person, such as a paraplegic, seated in a wheelchair drawn up alongside 
the vehicle, to swing his body and legs out of the wheelchair and up into 
a seat on the vehicle, and thereafter, to swing his legs and body out of 
the vehicle to return to said wheelchair, all without any assistance. 
Another object of the invention is to provide such a vehicle with motor 
mount assemblies that permit adjustment of the tension in the endless belt 
of each of the track mechanisms. 
It is still another object of the invention to provide such a vehicle with 
an air bladder seat suspension system, both for comfort and to permit 
adjustment of the longitudinal attitude of the seat. 
Further objects of the invention are to provide such a vehicle with a 
removable, steerable auxiliary wheel system that facilitates moving the 
vehicle whenever the vehicle becomes inoperable, and with a spring 
suspension system for the track mechanism for a smoother, more controlled 
ride.

The terms "front" and "rear" refer to the left and right portions of the 
vehicle as depicted in FIG. 1, and the terms "left" and "right" refer to 
the left and right sides of the vehicle as depicted in FIG. 2. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIGS. 1-3, a self-propelled, all-terrain vehicle, denoted 
generally by the numeral 10, is shown resting on a ground surface 12. A 
parallel pair of spaced-apart track mechanisms 14 are attached to a 
longitudinally elongated underframe 16, as may best be seen in FIG. 4. The 
underframe 16 includes parallel, horizontal, left and right inner rails 
34, each having a front end 34F and a rear end 34R. A front cross member 
36 joins the front ends 34F; a rear cross member 38 joins the rear ends 
34R. A horizontal rear plate 40 is attached to, and joins, a rear portion 
of each of the inner rails 34 and extends forward from the rear cross 
member 38 to a central portion 16C of the underframe 16. A horizontal skid 
plate 42 is attached to, and joins, a front portion 34F of each of the 
rails 34, and extends rearward from the front cross member 36 to the rear 
plate 40. A brush guard 37 comprising a horizontal bottom plate 37B and a 
forwardly and upwardly canted lip 37L extends forwardly from the front 
cross member 36. 
Each of the track mechanisms 14 includes an outer rail 44 disposed parallel 
to, and attached to, an inner rail 34, respectively. Each track mechanism 
14 further includes an endless belt 18 about idler wheels pivotally 
mounted to, and disposed between, an outer rail 44, and an inner rail 34, 
respectively, including a large front idler wheel 20, a large rear idler 
wheel 22, and two pairs of longitudinally spaced-apart, small idler wheels 
24 disposed in tandem between the front idler wheel 20 and the rear idler 
wheel 22. Each of the belts 18 is also in driving engagement with a rear 
drive sprocket 26 mounted for rotation to the shaft 30 of a hydraulic 
motor 32. 
The left and right hydraulic motors 32 are supported by left and right 
motor mount assemblies, denoted generally by the numerals 50, 50', 
respectively. The motor mount assemblies 50, 50' include upstanding, 
apertured, left and right motor mount lugs 52, 52' attached to the 
underframe 16 adjacent the rear cross member 38, and left and right motor 
mounts, 54, 54', respectively, as may be seen in FIGS. 4 and 6. Each motor 
mount 54, 54' includes a lower bracket portion 56, 56' attached to a motor 
mount lug 52, 52', and has a vertical, height adjustment slot 58, 58'. 
Each motor mount 54, 54' further includes an upper bracket portion 60, 60' 
integral with the lower bracket portion 56, 56' and extending upward 
therefrom. Each upper bracket portion 60, 60' has first 62, second 64, and 
third 66 apertures for receiving the shaft 30, forward drive port 68, and 
reverse drive port 70 of a hydraulic motor 32, respectively. Each upper 
bracket portion 60, 60' is adapted for supporting a hydraulic motor 32 
with its shaft 30 oriented laterally outward of the underframe 16. A 
height adjustment bolt 72, 72' is inserted through each motor mount lug 
52, 52' and through the height adjustment slot 58, 58' attached thereto, 
and fitted with a wing nut (not shown) for securing the motor mount 52, 
52' at a desired height with respect to the underframe 16. A laterally 
disposed, horizontal tie bar 80 extends from the lower bracket portion 56' 
of the right motor mount 52' to the lower bracket portion 56 of the left 
motor mount 52. Thus, the tension in each endless belt 18 can be increased 
or decreased by adjusting up or down, respectively, the position of each 
of the hydraulic motors 32 and the rear drive sprockets 26 attached to the 
shafts 30 thereof. 
The vehicle 10 further includes a seat assembly 90 disposed above and 
carried by the underframe 16 to provide a passenger seating surface 100 at 
a height above the ground surface 12 substantially equal to the height of 
the seat of a conventional wheelchair--that is, preferably in the range of 
20 to 27 inches above the ground surface 12, more or less. As may best be 
seen in FIGS. 2 and 4, the seat assembly 90 includes a flat, horizontal 
seat panel 92 having left and right side portions 95. The seat panel 92 
rests upon, and is attached to, a rectangular seat frame 93 comprising 
lateral front and rear support members 93F, 93R joined by longitudinal 
left and right support members 97. The seat frame 93 is centrally 
supported above the underframe 16 by left and right pairs of equal-length, 
longitudinally spaced-apart, vertical seat supports 94, each having a 
lower end attached to the rear plate 40 and an upper end attached to the 
longitudinal left and right seat frame support members 97, respectively. 
As may be seen in FIGS. 2 and 8, the seat plate 92 extends laterally 
outward of the vertical seat supports 94 and out over the tracks 18, which 
reduces the lateral distance that a disabled person would otherwise have 
to heft his body sideways in order to get on or off the seating surface 
100 of the vehicle 10. The seat panel 92 has a vent hole 91 to permit air 
flow from the underlying engine compartment 120, and is removable from the 
seat frame 93 for access to the engine compartment 120. 
The seat assembly 90 further includes an arm rest assembly, comprising left 
and right pairs of equal length, longitudinally spaced-apart vertical arm 
rest supports 96, each having a lower end attached to the seat frame 93 
and an opposite, upper end supporting a longitudinal arm rest strut 101 
extending between the vertical arm rest supports 96. Resting on, and 
attached to each strut 101 is an arm rest 98. At least one, and preferably 
both, of the front vertical supports 96 is equipped with quick release 
catches (not shown) for easy removal from, and reattachment to, the seat 
frame 93, in order to facilitate a disabled person's self-assisted 
mounting and dismounting the vehicle 10. 
The seat assembly 90 also includes left and right, vertical seat back 
supports 99, each having a lower end attached to the lateral rear member 
93R of the seat frame 93 and an opposite, free upper end. A removable seat 
back cushion 110 is attached to the seat back supports 99, and a seat 
cushion 112 rests upon the seat panel 92. 
In an alternative embodiment, the seat panel 92 is eliminated entirely and 
the seat assembly 90 instead includes a seat suspension system 130, as 
best seen in FIGS. 8-12, both for passenger comfort as well as to provide 
a means for adjusting the longitudinal attitude of the seat cushion 112. 
The seat suspension system 130 rests on an upper surface of the seat frame 
93, and includes spaced-apart, upper and lower air bladder support plates, 
132U, 132L, having size and shape substantially equal to that of the seat 
frame 93. A plurality of horizontally spaced-apart, inflatable air 
bladders 134 rest upon, and are attached to, an upper surface of the lower 
bladder support plate 132L and attached to a lower surface of the upper 
air bladder support plate 132U. As shown in FIG. 12, each bladder 134 has 
a hollow, inflatable, substantially toroidal rubber tube 135 and circular, 
apertured, upper and lower bladder mounting plates 136U, 136L attached to 
flat upper and lower surfaces of the tube 135, respectively. Mounting 
screws 139 and washers 140 are provided for mounting each bladder 134 
between the upper and lower bladder support plates 132 U, 132L, as shown 
in FIG. 11. The upper support plate 132U has a plurality of ventilation 
holes 143. A pair of air inlet/discharge ports 137 is provided on 
oppositely disposed exterior surfaces of each tube 135. The bladders 134 
communicate with one another by means of air hoses 138 inserted into ports 
137. Referring now to FIG. 9, in a preferred embodiment, there are 
provided air hose-interconnected front left and front right bladders 
132FL, 132FR, a centrally disposed bladder 132C, and air 
hose-interconnected rear left and rear right bladders 132RL and 132RR, and 
valve stems 142 on the left and right sides of the seat suspension system 
130 for separately introducing air under pressure into the front pair 
132FL, 132FR, the central 132C and the rear pair 132RL, 132RR of bladders, 
respectively, such that, by adjusting the relative air pressures within 
them, the longitudinal attitude A of the upper bladder support plate 
132U--and hence that of the seating surface 100--can be adjusted. 
It is particularly important that the legs of a paraplegic be restrained 
while riding the vehicle 10; accordingly, as shown in FIGS. 1 and 4, 
removable, laterally spaced-apart, left and right leg rests 150 extend 
forwardly from the lateral front support member 93F of the seat frame 93 
and thence downwardly to front left and front right portions of the skid 
plate 42, respectively. Like the arm rests 98, the leg rests 150 
preferably also have quick release catches (not shown). For additional 
passenger safety restraint, the seat assembly 90 is equipped with a lap 
belt 150 and shoulder belt 152. 
Referring now to FIG. 7, an internal combustion engine 160 is shown mounted 
to the underframe 16 with the engine drive shaft 162 oriented vertically 
downward and fitted with an engine drive shaft pulley 164. For adequate 
vehicle hill climbing ability, the engine 160 should preferably be rated 
at 12 to 16 horsepower. A hydraulic pump 166 is shown mounted to the rear 
skid plate 40 by a pair of pump mounting brackets 168, rearward of the 
engine 160, with pump driven shaft 170 also oriented vertically downward 
and fitted with a pulley 172. Dual drive belts 174 about the engine shaft 
pulley 164 and the pump pulley 172 couple rotation of the engine drive 
shaft 162 to the pump driven shaft 170. Such longitudinal spacing, instead 
of lateral spacing, of the engine drive shaft 162 and the pump driven 
shaft 170 is for maintaining a narrow lateral vehicle profile--that is, 
maintaining the track mechanisms 14 as close to one another as 
possible--thereby contributing to the ease of mounting and dismounting the 
vehicle. Moreover, since the engine 160 and hydraulic pump 166 are 
relatively heavy components, mounting them directly on the underframe 16 
helps achieve a low center of gravity for vehicle stability. The brackets 
168 mount in two pairs of longitudinally elongated slots 169 in the rear 
skid plate 40, shown in FIG. 21, to permit adjustment of the tension in 
the drive belts 174. 
Further to maintain the vehicle's narrow lateral profile, hydraulic fluid 
is stored in a hydraulic fluid tank 180 that includes left and right wing 
tank portions 180W disposed under the left and right side portions 95 of 
the seat panel 92, respectively, that are joined by, and communicate with, 
a rear tank portion 180R disposed behind the seat frame 93. The rear tank 
portion 180R has a filler port 182 for adding hydraulic fluid to the tank 
180. Preferably, the wing tank portions 180W are substantially triangular 
in longitudinal cross-section, having a pair of substantially triangular 
side walls 185 joined by a horizontal top wall 184, a forwardly and 
downwardly sloping bottom wall 186, and a vertical front wall 190. This 
arrangement, together with making the engine fuel tank 200 as an upper 
compartment to the hydraulic fluid rear tank, whereby they share a common 
wall, further saves space between the two track mechanisms 18 and 
contributes to the desired narrow vehicle profile. The engine includes an 
electric starter motor (not shown), which is powered by an electric 
storage battery 176 mounted to the vehicle 10 behind the rear portion 180R 
of the hydraulic fluid tank 180. 
Hydraulic drive control means 202 are provided for initiating forward, 
reverse and turning movements of the vehicle 10 over a ground surface 12. 
Left and right hydraulic drive hand controls 202 are attached to, and 
extend forwardly from, the left and right vertical arm rest supports 96, 
respectively. Each hand control 202 is equipped with an upstanding hand 
grip lever 204 having a lower end pivotally mounted thereto at pivot point 
204P for forward and reverse, hand-controlled movements within a 
longitudinal slot 206 therein. As shown in greater detail in FIGS. 21, 24, 
for each hand control 202 a control cable 208 is attached to a hand grip 
lever 204 at attachment point 204A above pivot point 204P. From each pivot 
point 204P, each cable 208 is looped around a cable pulley 215, thence 
rearward through a cable attachment bracket 209 within the hand control 
202 that secures the outer sheath of the cable 208; thence down behind the 
seat assembly 92, through a cable attachment bracket 209, thence 
terminating in a first cable end 208F that is connected to an upstanding 
rocker arm 211 pivotally attached at point 211P to the rear skid plate 40. 
Also attached to a rocker arm 211 is an opposite, second end of each cable 
208, from whence the cable 208 runs forwardly back to the point of 
attachment 204A on lever 204. Each rocker arm 204 is adjacent to a 
spool-type hydraulic control valve 179 that receives fluid under pressure 
conducted from the pump 166 through a hydraulic pressure gauge 163, 
pressure relief valve 165, and hydraulic fluid flow divider 149, whereby 
forward and rearward movements of the hand grip lever 204 cause 
corresponding movements of the rocker arm 211 and of the spool within the 
valve 179 attached to the rocker arm 211. Forward drive outlet ports 181 
and reverse drive outlet ports 183 on the left and right control valves 
179 are connected by hydraulic conduit 151 to the forward drive port 68 
and reverse drive port 70 of the left and right hydraulic motors 32. The 
arrows 311 in FIG. 23 show the direction of flow of hydraulic fluid, 
including the return flow from each of the motors 32 through a filter 217 
through an inlet port 161 into the hydraulic fluid tank 180. Thus, so long 
as the engine 160 is driving the pump 166, pushing only the right lever 
forward will cause the vehicle to turn left, pulling the same lever 
rearward will cause the vehicle to turn right, pushing the left and right 
levers forward will cause the vehicle to move forward, and pulling the 
left and right levers rearward will cause the vehicle to move rearward, 
the speed of movement being proportional to the amount of displacement of 
the levers 204. 
Referring now to FIGS. 5A, 5B, the vehicle 10 preferably has means 210, 212 
for spring coupling to the inner and outer rails 34, 44, the large front 
idler wheels 20 and the large rear idler wheels 22, respectively, as well 
as means 214 for spring coupling thereto each pair of small idler wheels 
24. The means 210, 212 each include a spacer bracket 216 interposed 
between, and joining, the front and rear portions of the inner and outer 
rails, 34 and 44, respectively. Each spacer bracket 216 has a 
laterally-disposed, cylindrical, first spacer shaft 228 about which is 
pivotally circumposed a first end bushing portion 219 of a longitudinally 
disposed band spring 218; an opposite, second end bushing portion 221 of 
the band spring 218 is adapted for rotational mounting of a large idler 
wheel 20, 22. A parallel pair of tension springs 231 connect central 
portions of each band spring 218 to the spacer bracket 216. Each of the 
means 214 includes a pair of longitudinal, oppositely-directed band 
springs 222 having first ends 225 joined by a laterally disposed, hollow, 
cylindrical bushing 233 pivotally circumposed about a laterally disposed, 
cylindrical, second spacer shaft 228 mounted between the inner and outer 
rails 34, 44, and opposite, free, second bushing ends 226 adapted for 
rotational mounting of small idler wheels 24. A tension spring 231 is 
provided for each means 214 and connects the free, second bushing ends 226 
thereof. Incorporation of means 210, 212, 214 into the vehicle 10 provides 
a smoother, more comfortable ride, particularly over rough terrain. 
In the event of engine failure or other mishap that renders the vehicle 
inoperable on remote or rough terrain, it is desirable to be able to roll 
the vehicle by means of a steerable auxiliary wheel system to the nearest 
road for transporting the vehicle to a repair facility. A steerable 
auxiliary wheel system, denoted generally by the numeral 240, is depicted 
in FIGS. 13-20, installed on the vehicle 10 and ready for use. Left and 
right rear wheel assemblies 242 are attached to rear portions of the outer 
rails 44 and left and right front wheel assemblies 244 are attached to 
front portions of the outer rails 44, respectively. Each wheel assembly 
includes an auxiliary wheel 250, rotatably mounted on a horizontal axle 
252, that are height adjustable between an upper retracted position (FIGS. 
14, 16A, 19A) and a lower, ground surface-engaging position (FIGS. 13, 
16B, 19B). The steering assembly system 240 comprising a removable 
steering column 232 having an upper end 232U with attached steering wheel 
235 and an opposite, lower end 232L, a removable steering column support 
234 attached to the front support member 93F and in supporting engagement 
with the steering column intermediate the upper and lower ends of the 
column 232, and a steering linkage means 238, attached to a lower, front 
portion of the vehicle 10, for imparting pivotal motions to each of the 
front auxiliary wheels 250 about a vertical axis V adjacent each of the 
wheels 250 in response to rotational motions of the steering wheel 235. 
Each of the front and rear wheel assemblies 242, 244, further includes a 
wheel height adjustment block 260 attached to an outer rail 44. As shown 
in FIGS. 17A, 17B, each block 260 has a vertically elongated back wall 
260B, and side walls 260S and a top wall 260T that extend laterally 
outward from the back wall 260B, defining a vertical, height adjustment 
channel 262. A vertically-elongated wheel mount 264 is adapted for 
vertical sliding movement within the height adjustment channel 262. For 
each of the rear auxiliary wheel systems 242, the wheel mount 264 has an 
aperture 264A into which is inserted a first, fixed end of a wheel axle 
252, a second opposite end of the axle 252 being oriented laterally 
outward from the vehicle 10, as shown in FIGS. 17A, 17B. For each of the 
front auxiliary wheel systems 244, however, instead of an axle 252 being 
directly attached to the wheel mount 264, a fixed portion 290F of a 
steering knuckle 290 is attached to, and extends laterally outward from 
the wheel mount 264, as shown in FIGS. 19A, 19B, and an axle 252 (shown in 
phantom outline) is attached to a steering arm portion 290R of the knuckle 
290 rotatable about a kingpin 290K. For mounting each of the blocks 260 to 
the outer rails 44, there are provided, as shown in FIG. 17B, a pair of 
apertured, spaced-apart mounting lugs 268 that extend laterally inward 
from the back wall 260B for securing the block 260 to an outer rail 44 by 
means of a block pin 300. The wheel mount 264 has a vertical, threaded 
bore 264B, shown in phantom outline in FIG. 17A. A wheel height adjustment 
crank 266 has a threaded vertical shaft 266S inserted through aperture 
260A in the top wall 260T and in threaded engagement with the threaded 
bore 264B, and an offset crank knob 266K, whereby rotation of the knob 
266K causes vertical movement of the wheel 250 mounted on the axle 252. 
That is, during periods of time when the steerable auxiliary wheel system 
240 is not in use, the wheels 250 are raised, by turning the crank 266 in 
a first direction, up to an upper, retracted position as depicted in FIGS. 
16A and 19A; but, when the system 240 is to be used, the wheels 250 are 
lowered, by turning the crank 266 in a second, opposite direction, down to 
a lower, ground surface-engaging position as depicted in FIGS. 13, 14, 
16B, and 19B. When the system 240 is not in use, the steering column 232 
and support 234 may remain installed on the vehicle as shown in FIGS. 13, 
14, or they may be removed from the vehicle and stored in some convenient 
location where they will be easily accessible in case the vehicle becomes 
inoperable. 
In addition to the steering knuckles 290, the steering linkage means 238 
preferably further includes an upstanding, apertured steering post 302, 
rigidly attached to the brush guard, through which is inserted the 
steering column lower end 232L, and an upstanding pivot arm 304 rigidly 
attached to the steering column lower end 232L and rotatable therewith. 
The means 238 also includes left and right lateral steering links 306, 
each having a first end 306A pivotally attached to the pivot arm 304 and a 
second, opposite end 306B, and left and right vertical steering links 308 
each having a first end 308A pivotally attached to a lateral steering link 
second end 306B and a second, opposite end 308B pivotally attached to a 
steering arm 290R. Therefore, for example, when the wheels 250 are lowered 
to ground surface 12 and the vehicle 10 is being rolled forward, rightward 
rotation of an upper portion of the steering wheel 235 moves the lateral 
steering links 306 rightward, which clockwise (as viewed from above) 
pivots the front steering arms 290R and attached wheels 250 about the 
kingpins 219K for executing a vehicle right turn (vice-versa, for 
executing a vehicle forward left turn) 
The underframe 16 is preferably made of mild steel and the idler wheels of 
UHMW.RTM. plastic. Except for the seat cushion 112, back cushion 110, and 
rubber bladders 134, 134C, the seat assembly 90 is preferably aluminum, 
square aluminum tubing being used for the seat frame 93, as well as for 
the arm rest assembly 90, and the leg rests 150. The motor mounts 54 are 
also preferably aluminum. The hydraulic fluid tank 180 and the fuel tank 
200 may be made of a rigid plastic or of aluminum. 
An alternative embodiment of the vehicle is depicted in FIG. 22, wherein an 
internal combustion engine 160 mounted on the underframe 16 instead drives 
a direct current electric generator 320, the electric power output of 
which is conducted through a voltage regulator 322 by electric cables 324 
to electric storage batteries 326. An electric motor 328 wired to the 
batteries 326 drives a hydraulic fluid pump 166. In this embodiment, a 
less powerful engine, rated at 2 to 4 horsepower, will suffice. 
Various changes and modifications will become obvious to those skilled in 
the art. For example, an electric solenoid-actuated, hydraulic spool valve 
could be susbstituted for each of the cable-actuated control valves 179, 
thereby eliminating the cables 208 and pulleys 215, with concomitant 
substitutions of electromechanical hand controls for the hand controls 202 
described and illustrated herein--all as is well known to persons of 
ordinary skill in the art. It is the intent that these changes and 
modifications are to be encompassed within the spirit of the appended 
claims and that the invention described herein and shown in the 
accompanying drawings is illustrative only and not intended to limit the 
scope of the invention.