A 4-wheel mobile vehicle including provision for controlling the steering position of each of the four (4) wheels so that every wheel's rolling axis will intersect at a common central point around which the vehicle will turn. The control is provided by a pair of cables which can interconnect each of the pair of wheels on each side of the vehicle to turn through similar turns in the opposite direction, and wherein the linear position of the cables are provided by a pair of specially cut cams which are positioned by the steering column. Each pair of wheels is further characterized by a support system which provides for vertical deviation of the front and back wheels without substantially causing the vehicle carriage itself to be vertically deviated by a substantial amount.

BRIEF DESCRIPTION OF THE PRIOR ART 
Coordinated 4-wheel vehicle steering is accomplished in several ways. For 
example, U.S. Pat. No. 4,373,603, issued to Carl D. Nelson, discloses a 
steering system control means for coordinating the turning movements of 
the rear wheels in response to the turning movements of the front wheels 
in a plurality of modes of operation. The patent has a sensing means which 
feeds an electrical signal to a control box which determines the position 
of the wheels in response to a selector switch selected by the operator of 
the vehicle. 
U.S. Pat. No. 2,910,131, issued to A. S. Krotz, discloses a steering 
apparatus for a steered vehicle which utilizes a plurality of hydraulic 
cylinders and hydraulic controls for positioning the front and back wheels 
on each side of a vehicle in a desired direction, either longitudinally or 
about a radius in response to the steering commands of an operator. This 
patent requires an extremely complex mechanical-hydraulic apparatus in 
order to accomplish the desired steering for each of the four wheels. 
U.S. Pat. No. 3,596,730, issued to Robert F. Cece, is another patent 
relating to steered vehicles wherein a complex mechanical-hydraulic system 
is utilized in order to control the position of the front and rear wheels 
of a vehicle so that it can traverse either a straight or curvilinear path 
about a common axis of rotation. 
U.S. Pat. No. 4,416,109, issued to John J. Slazas, illustrates one method 
of supporting the four (4) wheels of a vehicle in order to maintain the 
carriage of the vehicle in a substantially uniform plane while the wheels 
are deviating vertically about the common plane. 
BRIEF DESCRIPTION OF THE INVENTION 
All of the above patents relate to an apparatus for moving a carriage over 
a substantially flat plane while the steering apparatus is turning all of 
the vehicle wheels so that their rolling axes will all intersect at a 
common center point of rotation, traversing a linear path, or while some 
or all of the wheels are deviating vertically from the plane during the 
period of time one or more the wheels is moving over hills or valleys. 
This invention discloses a simple, mechanical means for both maintaining 
the carriage portion of the vehicle in a substantially uniform plane while 
the wheels are deviating vertically from the uniform plane. Furthermore, 
this invention provides for a simple mechanical means for steering the 
vehicale, either along a linear path or around a common point by providing 
control over all four (4) wheels so that the path of the wheels will be 
normal to a radius of each wheel which passes through the common point or 
axis of rotation. 
In one embodiment of the motorized vehicle, a frame means has a first and 
second side frame, each of which has first and second wheels, each side 
frame is journaled for rotation about a first axis parallel to a plane 
through the frame and each wheel is journaled about a second axis 
perpendicular to the plane. First and second turning means are coupled to 
the second axis journalling means for rotating the first pair of wheels in 
opposite directions from each other and the second pair of wheels, 
likewise, in opposite direction from each other. First and second cams 
have following which are controlled by a steering means rotatably attached 
to the frame and communicating with the cams. Means are provided for 
coupling the first and second cams followers to the first and second 
turning means, respectively, with the cams being configured in a manner to 
cause first and second pairs of wheels to follow a first and second 
circumference, both having a common center, when the steering wheel is 
turned. The turning means essentially comprises a cable passing over 
pulleys which are axially attached to each of the journalling means on one 
side of the carriage in a manner so that linear movement of the cable will 
cause the pulley journal to one wheel to turn in one direction and will 
cause the remaining wheel to turn a like number of degrees in the opposite 
direction. 
This invention also features a suspension system for the central frame or 
body of the vehicle in a manner so that a wheel can deviate vertically 
without causing a substantial deviation in the central frame of the 
vehicle which carries the cutting apparatus or other attachments for the 
vehicle. The suspension system essentially comprises a central frame with 
right and left side frames pivotally attached thereto, with each side 
frame supporting a wheel at each end. A bar is pivotally mounted to the 
front portion of the central frame with its ends each being connected to a 
side frame though pivot joints and connecting links. The side frames are 
likewise centrally journalled through a pivot to the central frame of the 
vehicle so that vertical movement of the wheels will be about the 
horizontal pivot and about the central frame and ends of the pivoted bar; 
thus, the wheels can move a substantial amount in a vertical direction 
without causing a substantial deviation in the vertical positioning of any 
attachments located under the body of the vehicle. The placement of a 
cutting apparatus also provides for complete cutting of grass or other 
material when the vehicle is making a turn about a location such as the 
edging around a tree or flower garden, for example.

DETAILED DESCRIPTION OF THE INVENTION SUSPENSION SYSTEM 
Referring to all of the drawings but in particular to FIGS. 1, 2, 3 and 4, 
the novel suspension system for this vehicle is illustrated. A vehicle 
generally referred to by arrow 10 comprises three separate assemblies, a 
central frame or body referred to by arrow 11 positioned in a generally 
horizontal plane, a right-hand side frame 12 and a left-hand side frame 
13. Central frame 11 essentially consists of mounting platform 14 having a 
seat 15 attached thereto at the rear of platform 14 and a motor 16 
attached at its front. A steering column 17 is rotatably attached at the 
mid-portion between motor 16 and seat 15. Steering column 17 has a 
steering wheel 18 attached at its end for rotating steering column 17 at 
the desire of an operator. 
Each of the right-hand and left-hand side frames 12 and 13, respectively 
are essentially identical excent mirror images of each other and 
therefore, only one side frame 13 will be fully described. It essentially 
consists of a central channel member 19 with fore and aft angular portions 
20 and 21 attaced thereto. Each wheel 22L and 23L is rotatably mounted on 
an "L" shaped bracket 24 (see FIGS. 1 and 3). "L" shaped bracket 24 has an 
hydraulic motor 25 attached thereto (FIG. 1) for supporting and driving 
each of wheels 22L, 23L, 22R and 23 R. A pair of wheels 22L and 23L are 
likewise attached to fore portion 20 and aft portion 21, respectively, by 
"L" shaped bracket 24 having vertical shafts or journals 30 and 31 (see 
FIG. 5 or 6) which in turn have pulleys 32 and 33 rigidly attached 
thereto. Both right-hand side frame 12 and left-hand side frame 13 are 
attached to central frame 11 through a horizontal shaft 34 which is 
mounted under platform 14 and extends on each side thereof. Side frame 13 
is rotatably journalled in a bearing 35 which is attached to a "U" shaped 
member 36 about a first axis. Member 36 is welded to central channel 
member 19. 
The second point of attachment for side frames 12 and 13 is provided by a 
horizontal bar 37 which has a pivot 38 centrally located along bar 37. 
Pivot 38 is attached to the forward end of platform 14. Bar 37 is 
supported by extensions 39 and 40 which are each attached to fore portion 
20 on the left-hand side frame 13. A tie-rod 41 is pivoted at 44 and 43 to 
extension 39 and to horizontal bar 37. Tie-rod 42 is pivoted to extension 
40 through a pivot 46 and is attached to horizontal rod 37 through a pivot 
45. 
SUSPENSION SYSTEM OPERATION 
The operating of the suspension system can be best illustrated by referring 
to FIGS. 3 and 4. In these figures a single wheel 22L is shown positioned 
in a new position 22L' which has been lifted as a consequence of a raise 
in the surface of the earth by a amount D1. Thus, fore portion 20 has 
likewise been raised to a position 20'. However, horizontal shaft 34 has 
only been raised to a new location 34' which is a distance D3. It should 
be noted that distance D3 is substantially less than distance D1. The 
second support point represented by pivot 38 has likewise been raised by a 
distance D2 which is also substantially less than the distance D1. Thus, 
when wheel 22L is raised to the new position 22L' which is a distance D1, 
then extension 39 is raised to a new position 39', raising tie-rod 41 to 
the new position 41'. Since tie-rod 41' is tied to horizontal bar 37 at 
linkage point 43, horizontal bar 37 will raise to the new position 37; 
raising pivot point 38 to 38'. As perviously discussed, this distance D2 
is substantially less than the distance D1 since both the front of central 
frame 11 and the side of central frame 11 are raised by a distance D2 and 
D3, respectively, both of which are substantially less than the distance 
D1. Any attachment to central frame 11 will likewise be shifted out of its 
position with the ground by a lessor amount than would ordinarily be 
expected. Thus, the suspension assembly described causes a substantial 
reduction in the vertical shift of any attachments connected to the under 
portion of central frame 11, such as, for example, grass cutting heads 50, 
as illustrated in FIGS. 1 and 2. 
STEERING APATUS 
Referring to FIGS. 5 through 9, but in particular to FIGS. 5 and 6, the 
steering control assembly essentially comprises first and second cams 51 
and 52, respectively, which operate the left side wheels and right side 
wheels, respectively. Cam 51 has a cam follower 54, and cam 52 has a cam 
follower 55. Joining cams 51 and 52 is a rack gear 53, and a pinion gear 
49 attached to steering column 17. Each of cam followers 54 and 55 is 
attached to a rod 56 which communicates with a spool valve 57 and a piston 
rod 58 for positioning cylinder 59. 
The actual details of operation of the spool valve and positioning cylinder 
are better illustrated with a description of FIG. 7 which will follow. A 
clamping apparatus 60 is attached to spool valve 57 and clamped to a cable 
61 by means of a plurality of bolts 62. Cylinder 59 is connected to 
platform 14 through a bracket 63 and bolt 64. Cable 61 travels around an 
idler pulley 65, around pulley 32, another idler pulley 66, through a 
third idler pulley 67 and pulley 33, and then around idler pulley 68 to 
form a complete loop, noting that cable 61 passes around pulley 33 so that 
pulley 33 turns in the opposite direction from pulley 32. Clamp 70 
connects control valve 57 to cable 71 for the right-hand wheels. Cable 71 
passes around pulleys 75, 73, 72, 79, 77 and 76 in a like manner as cable 
61 just described and turns wheels 22R and 23R together in like angles of 
rotation but in opposite directions. 
DIRECTIONAL CONTROL OPERATION 
The directional control will be explained separately from the actual 
operation of the various power steering cylinders and the hydraulics 
associated therewith. The directional control operation is best determined 
by referring to FIGS. 5 and 6. 
In FIG. 5, vehicle 10 is positioned for straight ahead steering, that is 
wheels 22L, 23L, 22R and 23R are oriented so that the rolling axes of the 
wheels are parallel. Referring to cams 51 and 52, it is noted that cam 
followers 54 and 55 are located at point L1 and L2, respectively, on cams 
51 and 52, respectively. In the event it is desired to rotate the vehicle 
10 about a certain location, such as point P1, as seen in FIG. 6, then it 
is necessary that the rolling axes of all four wheels pass through point 
P1 (as seen by radii R2, R2, R1, R1). Thus in order for vehicle 10 to 
traverse about point P1, each pair of wheels 22R and 23R and 22L and 23L 
must traverse individual circumferences spaced by the distances of radii 
R1 and R1, respectively. As can be seen in FIG. 6, the wheels 22R and 23R 
turn through a much greater turning angle than wheels 22L and 23L. In 
order to accomplish this, pinion gear 49 is rotated by steering shaft 17 
in the direction of arrow 80, which will move the rack 53 in the direction 
of arrow 81. This will cause cam follower 54 to drop down on cam 51 a 
distance A1, while cam follower 55 will climb on cam 52 a distance A2 to 
points L'1 and L'2 respectively. Cable 61 has moved in the direction of 
arrow 83, while cable 71 has moved in the direction of arrow 84. The 
movemnet of cable 61 in the direction of arrow 83 a distance B1, will 
cause pulleys 32 and 33 to rotate clockwise and counterclockwise 
respectively on journals 30 and 31, causing the wheels to rotate to the 
position illustrated in FIG. 6. Cable 71, on the other hand, will move a 
distance B2 in the direction of arrow 84, a greater distance causing 
pulleys 73 and 77 to also rotate clockwise and counterclockwise, 
respectively on journals 74 and 78, so that wheels 22R and 23R assume a 
position normal to radius R2. In the event the opposite direction of 
rotation is desired, rack and pinion gear 49 need only to be turned the 
opposite direction which will cause the cables to move opposite to that 
illustrated in FIG. 6. 
In order to facilitate the steering of a substnatially heavy mowing 
machine, the cam followers 54 and 55 are coupled to a conventional power 
steering circuit which is illustrated in FIG. 7. Cam follower 55 is shown 
in contact with cam 52 (FIG. 7). Control valve 57 is a three position 
4-way valve having a cut-off position 90, a direct flow position 91 and a 
reverse flow position 93. Hydraulic lines 93 couple the control valve 57 
to sump 94 and hydraulic line 95 couples sump 94 to a pump 96 and from 
pump 96 to a line 97 to control valve 57. Line 98 couples control valve 57 
to the cap end 99 of positioning cylinder 59 while line 100 couples 
control value 57 to the rod end of the cylinder, Pistor 102, which is 
internal to cylinder 59, is connected to piston rod 58 as illustrated, 
which is in turn connected to a movable spool in control valve 57. A 
spring 103 and spring washer 104 apply a bias on rod 56, which in turn 
supports cam follower 55 and is connected to the movable spool in control 
valve 57 in a manner to maintain cam follower 55 against the surface of 
cam 52. 
The hydraulic control system of FIG. 7 operates in the following manner. 
When cam 52 is shifted to the left, as indicated by arrow 107, cam 
follower 55 moves down cam 52 due to the force of spring 103, causing 
valve 57 to shift to its position 91. In position 91, pump pressure flows 
from pump 96 to port 99 of cylinder 59 causing piston rod 58 to extend, 
which in turn moves cam follower 55 downward until it engages cam 52. Any 
further movement of piston rod 58 will force rod 56 to retract against 
spring 103, which will shift valve 57 back to its neutral position 90 
causing piston rod 58 to stop moving and the system to come to rest. 
If cam 52 is moved to the right, as indicated by arrow 108, follower 55 is 
forced upward causing valve 57 to shift to its position 92, which allows 
pump pressure to flow to the rod end of cylinder 59 and retract piston rod 
58. As rod 58 retracts, follower 55 also retracts until spring 103 can 
shift valve 57 back to its neutral position 90. Since valve 57 is attached 
to cable 61, any vertical movement A1 (FIG. 6) of cam follower 54 will 
cause a similar movement B1 of cable 61. 
In the aforementioned manner, any movement of cam 52 will cause the cam 
follower to automatically traverse the contours dictated by the cam's 
surface and move the cable accordingly. It would also be possible for the 
present invention to operate without power steering whereby the cam 
followers 55 and 54 would be tied directly to cables 61 and 71. 
FIG. 8 represents a cam having the proper configuration to accomodate the 
steering described in this invention. The cam has approximately a 70 
degree slope in the upper portion 110 of the cam, with respect to 
horizontal and a 40 degree slope in the lower portion 112 of the cam, as 
illustrated. A gradual curve 114 joins the two slpes in between. The cam 
is developed by the lines illustrated as D1, D2, D3, D4, D5, D6 and D7 
etc., wherein each point on the upper portion 110 corresponds with an 
angular position of the wheels on the inside of the turn while the points 
on the lower portion 112 of the cam correspond to the angular position of 
the wheels on the outside of the turn. The wheels on the inside of the 
turn obviously turn through a greater angle, as illustrated in FIG. 6. 
Therefore the slope of the cam must be steeper for the inside turning 
wheels than the outside wheels and the slope difference between 110 and 
112 depends on the width of the vehicle or lateral spacing of the wheels. 
Thus point DO represents the location of the cam follower for straight 
ahead travel of the vehicle and is equivalent to the position L1 and L2 
shown in FIG. 5. Each representative distance D1, D2, D3, etc., through 
D11 represent points closer to the sharpest turning radius that the 
vehicle can make. Thus, D11 represents the sharpest radius that the 
vehicle can turn; while D1 represents the radius slightly less than 
infinity. Each point from D11 through D1 represents equal increments on 
transverse line 113 (FIG. 6) taken from the farthest determined distance 
to the sharpest radius desired to be turned by the vehicle. While vehicle 
rotation point P1 (FIG. 6) is a very sharp or short turning radius. The 
turning radius could be even less. In other words, point P1 could be moved 
to the center of the vehicle, if desired, with the wheels turning through 
angles to the right of the left of more than 90.degree.. 
The grass three cutting heads 50 are conventional in design and arranged in 
an overlapping pattern extending laterally approximately to the edge of 
the wheels. The heads 50 are located slightly ahead of line 113 (FIG. 6) 
so the operator may steer in a normal manner to move closer or away from 
an obstruction with 4-wheel type steering. 
Alternate embodiments for cam configurations are illustrated in FIGS. 9 and 
10. In FIG. 9, steering column 17 rotates cams 51a and 51a, with cam 
follower 54 following cam 51a. Cam follower 55 is behind cam 54 and cannot 
be seen. In all other respects the apparatus of FIG. 9 functions identical 
to that of the appartus described previously. 
In FIG. 10, the cams are separated with cam 51b having cam follower 54 in 
contact therewith and cam 52b having cam follower 55 in contact therewith. 
Steering column 17 drives a chain sprocket 106 which is coupled through a 
chain 107 to sprockets 108 and 109, respectively. Each of sprokets 108 and 
109 drive cams 51b and 52b in identical manner to that shown in FIG. 9, 
with cam followers 54 and 55 functioning exactly as they are described in 
the previous figures. 
The cam follower has been illustrated with a single cam surface. It is 
obvious that the cam can be made from a plate with a cam cut as a slot in 
the plate, so that the cam follower can fit into the slot and thereby not 
require a spring to maintain the cam follower in contact with the cam 
surface since the cam follower will be trapped by the slot. It is also 
obvious that other cam configurations can be utilized with or without 
power steering and still be well within the spirit and scope of this 
invention. 
This invention basically describes a vehicle particularly useful for mowing 
grass and the like which has an unique method for maintaining the cutting 
heads close to the surface being cut regardless of the vertical position 
of the wheels as they traverse the surface of the earth. Furthermore, the 
invention describes an unique method for steering the vehicle so that it 
will maintain all wheel turning about a common point with no wheel 
scuffing, since each of the wheels will travel an individual circumference 
about the common point of rotation of the vehicle through substantial 
turning angles in excess of 90.degree.. 
It is obvious that other modifications can be made and still will be well 
within the spirit and scope of this invention as described in the 
specification and appended claims.