Suspension with interconnected torsion bars

A vehicle suspension system includes two laterally spaced forward wheel assemblies and two laterally spaced rear wheel assemblies together supporting a vehicle body. Each wheel assembly includes a wheel and a wheel mounting connecting the wheel to the vehicle body for movement relative to the body in the generally vertical direction. Respective first mechanical coupling members interconnect each wheel assembly to the laterally adjacent wheel, and respective second mechanical coupling members interconnect each wheel assembly. The respective second mechanical coupling members are interconnected to control the roll of the vehicle.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to improvements in the suspension system for 
vehicles, and specifically relates to systems in which the suspension 
elements of the respective wheels are mutually interactive, so as to 
provide substantially consistent wheel loading on the wheels not directly 
influenced by wheel travel, and providing improved overall ride and 
handling characteristics for motor vehicles. 
2. Description of the Background Art 
In recent times there has been a trend towards resilient sprung suspension 
systems, incorporating variable damping rates and adjustable spring rates, 
in an attempt to improve vehicle stability and reduce movement of the 
vehicle body relative to the surface being traversed. 
Some other more advanced suspension systems, commonly referred to as active 
or semi active suspension systems, incorporate a number of sensors which 
monitor information such as, vertical wheel travel and body roll, as well 
as speed, acceleration, steering and braking commands. This and other data 
is processed by an on-board computer (ECU) which instructs hydraulic or 
pneumatic actuators to extend or contract at high speed to raise or lower 
the wheels to follow the uneven terrain, while the vehicle body follows a 
more level path, without bouncing, rolling and pitching. 
These active suspension systems require an intelligent back-up system and 
call for a substantial input of external energy, drawn continually from 
the vehicle's engine, to operate the actuators that effect the adjustments 
to the suspension system. 
The active suspension systems described are not only expensive to 
manufacture and maintain in operation but are subject to electronic and 
hydraulic failures, such as leaking hydraulic seals, due to the extreme 
complexity of these suspension systems. 
SUMMARY OF THE INVENTION 
It is therefore an object of this invention to provide a vehicle suspension 
system which enables the vehicle to exhibit many of the benefits of the 
active suspension systems but which is of simple construction and can be 
utilised for long periods without the associated expenses and complexities 
of an active suspension system, that require frequent adjustments and 
servicing. 
With this object in view there is provided a vehicle suspension system 
comprising two laterally spaced forward wheel assemblies and two laterally 
spaced rear wheel assemblies together supporting a vehicle body, each 
wheel assembly including a wheel and a wheel mounting connecting the wheel 
to the vehicle body for movement relative to the body in the generally 
vertical direction, respective first mechanical coupling means 
interconnecting each wheel assembly to the laterally adjacent wheel 
assembly, respective second mechanical coupling means interconnecting each 
wheel assembly to the longitudinally adjacent wheel assembly, each said 
first and second mechanical coupling means being adapted to urge in 
response to movement of one wheel assembly in a substantially vertical 
direction a movement of the other wheel assembly connected to said same 
mechanical coupling means in the opposite direction, whereby said first 
and second mechanical coupling means together control pitch and roll of 
the vehicle body and to maintain substantially consistent loading on all 
wheels and thereby maintain traction on all wheels. 
The respective first and second mechanical coupling means provide a 
mechanism whereby, when relative movement occurs in the vertical direction 
between one wheel and the vehicle body, an opposite movement is urged 
between the longitudinally adjacent and laterally adjacent wheels 
respectively. If the mechanical coupling means possesses resilience, the 
degree of movement will be different, the difference being related to the 
degree of resilience in the mechanical coupling means and the loading on 
the relevant wheels. 
In a construction where all of the mechanical coupling means are rigid, the 
suspension system will provide substantially complete avoidance of both 
roll and pitch control of the vehicle body as the vehicle travels uneven 
terrain or is subjected to dynamic loadings, such as surface 
irregularities or cornering at speed. 
If there is a degree of resilience in the first mechanical coupling means, 
this will allow a degree of pitch of the vehicle body, the level of pitch 
being related to the degree of resilience in the transverse or first 
coupling means. Similarly, resilience in the second mechanical coupling 
means will allow a degree of roll of the vehicle body, the level of roll 
being related to the degree of resilience in the longitudinal or second 
coupling means. 
It is often preferable to provide a degree of resilience in each of the 
respective mechanical coupling means to afford an increased comfort to the 
occupants of the vehicle, and when resilience is thus provided, it 
normally becomes necessary to also avoid pitch and/or roll by providing a 
particular form of interconnective means between the respective first 
mechanical coupling means and/or the respective second mechanical coupling 
means. Generally, due to the geometrical and mechanical advantages present 
in the design of conventional vehicles, it is considered more important 
that roll motions be restricted than pitch motions. 
Where an interconnection between the two second mechanical coupling means 
is provided, extending in the lateral direction of the vehicle, the 
interconnection is constructed so that angular movement occurring in the 
mechanical coupling means on one side of the vehicle urges an angular 
movement in the opposite direction in the mechanical coupling means on the 
opposite side of the vehicle, preferably an equal angular movement. 
Preferably each first mechanical coupling means includes respective 
elongate members coupled one to each laterally spaced wheel assembly to 
angularly move in response to the generally vertical movement of the wheel 
mounted thereon relative to the vehicle body. The respective elongate 
members of each first mechanical coupling means being coupled so said 
angular movement of one elongate member will urge angular movement in the 
opposite direction of the other elongate member of that first mechanical 
coupling means. Preferably the respective movements are equal. 
The second mechanical coupling means is similarly constructed but is 
arranged with respect to the longitudinally spaced wheel assemblies. 
In a preferred embodiment wherein each of the first and second mechanical 
coupling means include respective elongate members coupled to each wheel 
assembly, the respective two elongate members of each mechanical coupling 
means are interconnected by gear means. The gear means being arranged so 
angular movement of one elongate member will urge angular movement of the 
other elongate member in the opposite direction. The relative movements 
may be equal or differ to a limited degree. 
With this arrangement, torsional forces in the vehicle body normally 
generated when axle articulation takes place are minimised. 
The currently proposed suspension system also substantially equalises the 
loads borne by each of the wheels when a vehicle traverses undulating 
terrain. A typical example of this situation is when the front left wheel 
and the back right wheel may be positioned on higher ground than the front 
right and rear left wheels respectively. In conventionally sprung vehicles 
fitted with traditional progressive suspension systems the axle 
articulation thus described causes the loads to be borne principally by 
the two wheels on the higher ground while traction is lost at the 
diagonally opposite wheels located in the hollows, which become the lesser 
loaded wheels. This type of axle articulation frequently leads to the 
spinning of the lesser loaded wheels, which in turn can cause the vehicle 
to become stuck or dangerously positioned. 
It should be appreciated that the system differentiates intrinsically 
between static and dynamic situations. Significant deformation of the 
resilient elongate members occurs only in dynamic situations when impulse 
forces are applied momentarily causing displacement of the relatively 
light wheels but not the heavier vehicle body. This behaviour is similar 
to conventionally suspended vehicles, but if the vehicle is stationary or 
moving slowly through undulating terrain, the body and the elongate 
members have time to move to positions where there is negligible spring 
deformation, thereby preventing unweighting of wheels, and thus 
maintaining traction. 
As previously referred to in a preferred construction, each mechanical 
coupling means comprises two elongate members, one coupled to each of two 
wheel assemblies interconnected by the mechanical coupling means. The 
respective elongate members being interconnected so rotation of one in one 
direction urges rotation of the other in the opposite direction, 
preferably an equal degree of rotation or of a similar order. This 
construction results in the minimisation or prevention of changes in the 
spring forces at each wheel supporting the vehicle during axle 
articulation, hence maintaining even wheel weights and therefore traction 
and secondly no torsional forces are developed in the vehicle body. 
In one arrangement the elongate members may be of torsion bar like 
construction, and arranged with the torsion bars functionally connected to 
the front wheels to extend backwards towards the back wheels while other 
torsion bars associated with the back wheels extend forwards towards the 
rear termination of the front torsion bars. The connection between the 
adjacent ends of the front and rear torsion bars may be of a gear form or 
a system of levers to achieve the required reversal in the direction of 
rotation. 
Thus when one wheel (such as the front left wheel) on one side of the 
vehicle is forced upwards it tends to cause the linked wheel on the same 
side (rear left) to be thrust down with an approximately equivalent force 
thereby ensuring approximately equal wheel loading on all wheels in non 
dynamic driving contexts. The same result is achieved between the front 
and rear wheels on the opposite side of the vehicle and between the two 
front wheels and the two rear wheels. 
The suspension system may also be provided with at least one lateral 
linkage, between the left and right hand side mechanical coupling means. 
One lateral link provides roll stability by connecting the torsion bars on 
one side of the vehicle to the torsion bars on the opposite side, so that 
when the two wheels on one side of the vehicle are forced up (or down) 
simultaneously this urges a movement of the pair of wheels on the other 
side of the vehicle in the same upward (or downward) direction. In this 
way roll stability of the vehicle is controlled without the inclusion of 
roll stabiliser bars which are commonly fitted to conventionally suspended 
vehicles, and which limit free axle articulation movements. It should be 
noted that this transverse linkage does not contribute to the support of 
the vehicle, but merely defines its roll attitude and stability without 
imposing a restriction on axle articulation movements. 
The vehicle suspension system herein disclosed provides a vehicle supported 
above the terrain in the pitch direction by the front and rear lateral 
coupling means and supported in the roll direction by the longitudinal 
coupling means linking the front and rear wheels on the same sides. If, 
for example, the longitudinal coupling means were to be removed, the 
vehicle would subside towards the left or right. Similarly, if the front 
and rear lateral coupling means were to be removed, then the vehicle would 
subside. Therefore it is the combination of support in the individual 
lateral and longitudinal directions which provide support in all 
directions while still permitting unrestricted vertical wheel travel in 
uneven terrain and whilst substantially equalising the load borne by each 
wheel. 
Expressed in general terms there is provided a vehicle suspension system 
comprising two laterally spaced forward wheel assemblies and two laterally 
spaced rear wheel assemblies together supporting a vehicle body, each 
wheel assembly including a wheel and a wheel mounting connecting the wheel 
to the vehicle body for movement relative to the body in the generally 
vertical direction, mechanical coupling means interconnecting each wheel 
assembly to the adjacent wheel assemblies said mechanic coupling means 
also being arranged to generate a movement that is a proportional average 
of the movement of the two wheels connected thereto, and means to 
selectively transfer said generated movement to the mechanical coupling 
means on the opposite side of the vehicle. 
Further scope of applicability of the present invention will become 
apparent from the detailed description given hereinafter. However, it 
should be understood that the detailed description and specific examples, 
while indicating preferred embodiments of the invention, are given by way 
of illustration only, since various changes and modifications within the 
spirit and scope of the invention will become apparent to those skilled in 
the art from this detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the drawings, the components of the vehicle which are not essential to 
the description of the invented system have been omitted. 
Referring to FIGS. 1 and 2 the suspension system and vehicle are shown 
diagrammatically with its front of the vehicle facing the top of the page 
and with the front wheels turned towards the left. The front left wheel 1 
the front right wheel 2, the rear right wheel 3 and rear left wheel 4 
support the vehicle. 
The ladder type chassis frame 5 has a series of cleats 6 on the perimeter 
thereof. Wishbone arms 7, 8, 9 and 10 are of a commonly known construction 
and are pivotally connected to the chassis 5 to permit the wheels to move 
in generally upward and downward directions with respect to the chassis on 
the pivot axes 7a, 8a, 9a and 10a respectively. A second wishbone (not 
shown) may also be provided to locate the wheel in the third dimension or 
the wheel may alternatively be located in the vertical plane by way of a 
shock absorber type unit such as is known in vehicles. Other wheel 
location constructions such as trailing arms, radius rods and similar 
devices, which permit the relative movements between the wheels and 
chassis may be used instead of the illustrated wishbone units. 
The contra-rotating torsion bars 11, 12 which support the front end of the 
vehicle are laterally located at the front of the chassis so that torsion 
bar 11 is directly linked to the suspension of the front left wheel 1. 
Likewise torsion bar 12 is directly linked to the suspension of the front 
right wheel 2. 
The longitudinal pair of contra-rotating torsion bars 13, 14 on the right 
side of the vehicle are linked to the suspension of the wheels 2 and 3. 
The rear lateral pair of torsion bars 15, 16 are connected to the 
suspension of the rear wheels 3 and 4. Finally, the left hand side pair of 
longitudinal torsion bars 17, 18 are connected to the left hand side 
wheels 4 and 1. 
With reference to the front end of the vehicle, the torsion bars 11, and 12 
are connected to the wishbone linkages 7 and 8 respectively by way of 
intermediate linkages 19, 20 respectively, which may be provided with ball 
joint ends which accept the changing angles between the relevant torsion 
bars and wishbone linkages. 
Similar intermediate linkages are shown connecting the rear axle lateral 
torsion bars 15, 16 to the rear wishbones linkage 9, 10 respectively 
indicated at 21 and 22. 
Any of the torsion bars linkages may be joined to the wishbone linkages (or 
any other wheel support linkage mechanisms) in a similar way to that 
described above by way of intermediate linkages, or the torsion bars may 
alternatively be connected to the wishbone or trailing arm or other wheel 
location means by way of any other convenient method. An example of this 
is shown with reference to the longitudinal torsion bars 13, 14, 17, 18 
which are mounted so that their rotational axes are concentric or coaxial 
with reference to the axes of the wishbones pivots 7a, 8a, 9a, 10a so that 
the ends of the bars may be rigidly fixed to the associated wishbones. 
At any convenient and/or advantageous location near to the ends of the 
respective torsion bars there are provided support means generally 6, 
which locate the torsion bars with reference to the chassis or vehicular 
body, whilst permitting the torsion bars to rotate within the support 
means. The support means may typically be provided with needle roller 
bearings or brass bushes which permit free rotational movement of the 
torsion bars. 
It may be advantageous in some contexts to provide rubber bushings instead 
of bearings, so as to introduce some damping effect between the torsion 
bars and the chassis in a similar way to the damping provided by 
telescopic dampers or other components commonly known as shock absorbers. 
Alternatively, shock absorbers, may be provided between any of the torsion 
bars and the chassis or between two adjacent torsion bars. An advantage 
arising from positioning the shock absorbers or dampers at different 
points along the lengths of the different torsion bars is to permit the 
vehicle to be tuned with individual roll and pitch damping characteristics 
to enhance ride and handling as seen appropriate for each vehicle type. 
Therefore dampers or shock absorbers located on the longitudinal torsion 
bars will define the extent of roll damping while those on the lateral 
torsion bars limit pitch resonance. The distance along the torsion bar 
members from the anchorage to the wheel suspension to the damper or shock 
absorber defines how much undamped springing or resilience is available in 
the torsion bar. Thus there is permitted a wider range of turnability than 
in conventional shock absorber systems. 
Alternatively, it may be convenient and easier to package the shock 
absorbers into the conventionally available spaces in the vehicle wheel 
arch area, and therefore provide conventional telescopic dampers as 
indicated at 24a, 24b, 24c and 24d respectively. 
As previously indicated, the torsion bars linking orthogonal wheels are 
connected so as to contra-rotate at the juncture thereof. In the case of 
the front lateral pair of torsion bars 11, 12, these are shown in the 
FIGS. 1 and 2 terminating in a slightly overlapping relation near a 
central point between the wheel. The individual torsion bars are provided 
with respective gear teeth formations 25a, 25b in the area of overlap 
which inter-mesh and thereby ensure contra-rotational movement of the two 
torsion bars 11, 12 at this point. The extent of contra-rotation is 
defined by the extent of the wheel articulation taking place (which does 
not require spring resilience) as opposed to the amount of wheel travel 
arising out of the impacting of two orthogonally adjacent wheels 
simultaneously with a bump which causes the torsion bars to twist along 
their lengths to provide a degree of springing. 
An alternative arrangement to provide the contra-rotational is shown at the 
rear axle lateral torsion bars 15 and 16 in FIGS. 1 and 2. In this 
example, the two torsion bars are mounted on the same axis each provided 
with a bevel gear 26a, and 26b facing each other. In between the two bevel 
gears, a third bevel gear 26c is located which meshes with both gears 26a 
and 26b. The intermediate or third bevel gear 26c is rotatably mounted on 
a fixed axis in the chassis or body 5 by the spigot 26d so as to provide 
easy relative contra-rotational movement of the two torsion bars 15 and 
16. 
The contra-rotational components between the two longitudinal pairs of 
torsion bars 13, 14, and 17, 18 are similar to that at the rear of the 
vehicle and as described above, in that the two torsion bars of each pair 
terminate in an opposing relation and are provided with respective 
opposing bevel gears 27a, 27b and 28a, 28b respectively. The opposing 
gears 29, 30 each mesh with a third bevel gear 27c, 28c respectively 
rotatably mounted in the body 5 as previously described with reference to 
the bevel gear 26c mounted at the rear of the body. However, as shown in 
FIG. 2 and FIG. 3, the three gears 31 are mounted on a carrier ring 33 and 
34 which can itself rotate on a longitudinal axis. The respective 
longitudinal side mounted contra-rotational assemblies 27, 28 as seen in 
FIG. 2 are structurally similar to a differential gear units as commonly 
found in the drive train of vehicles and these components will now be 
described with reference to FIG. 4. 
It should be noted that although full circle gears or toothed 
contra-rotational devices are generally illustrated in the drawings the 
same contra-rotational motion of the respective torsion bars may be 
achieved by segments of bevel and ring gears as in use these components 
only need rotate through a maximum of about 45 degrees in each direction 
from a central position. Alternatively bevel and other types of geared 
components may be replaced by lever arms which are flexibly connected (by 
way of ball joints or other components such as bushings) arranged such 
that as one torsion bar turns in one direction, the adjacent torsion bar 
turns in the opposite direction as will be seen in the further description 
of the operation of the transverse central member 35 linking 
contra-rotating assemblies 27 and 28. 
Referring to diagrams A and B of FIG. 3 there is shown an elevation view 
through the suspension in the plane of the gear systems 27, 28, as seen 
from the rear of the vehicle. 
The central contra-rotational gear system drivably link the front left and 
rear left hand wheels by way of torsion bars 17 and 18. These torsion bars 
terminate in bevel gears 28b and 28a. It should be understood that any 
number of bevel gears 31 may be incorporated. 
The bevel gears 31 mesh with bevel gears 28a, 28b and 27a and 27b and are 
conveniently rotatably housed on spigots located in an outer ring member 
32a and 32b that they effect the relative contra-rotational movements of 
the two torsion bars 17, 18 during diagonally opposite wheel 
articulations. Additionally, if both torsion bars move in the same 
direction such as if the side of the vehicle is changing height at both 
wheels on one side then the ring housing 32 will itself rotate with 
respect to the chassis. 
Referring further to diagram B in FIG. 3, each ring housing 32a and 32b is 
additionally equipped with a cleat or ball joint 33 and 34 which provides 
a flexible anchorage for a rigid bar 35 which interconnects the two ring 
housings. The central transverse bar 35 is similar in construction, and 
has similar termination components at 33, 34, to a conventional Panhard 
rod, commonly used in vehicle suspensions, although its function in this 
instance is entirely different. 
It will be noted that the central transverse bar 35 is connected to the 
cleat 33 located on the upper portion of the ring housing 32a associated 
with the left hand side longitudinal torsion bars, and on the cleat 34 on 
the underside of the ring housing 32b, on the right side of the vehicle. 
Therefore, if the two wheels on the right side of the vehicle are moved 
upwards with reference to the chassis, such as in consequence to the 
vehicle turning to the left as shown in FIG. 1, then the two torsion bars 
13, 14 will turn in an anti clockwise direction, and while this will not 
cause the bevel gears 31 to turn it will cause the entire outer housing 
ring assembly 32b to turn in an anti clockwise direction as seen in 
diagram B in FIG. 3b. The central connecting rod 35 will therefore be 
pulled towards the right side of the vehicle, and since it is connected to 
the upper portion of the ring housing at 33, it will cause the left ring 
housing 32a to rotate in a clockwise direction. This then in turn urges 
the left wheels to be moved upwards which has the effect of lowering the 
left side of the vehicle as a consequence the roll angle of the vehicle, 
caused by the cornering motion of the vehicle, is reduced. 
Significant forces are only generated in the longitudinal torsion bars and 
respective connections when the vehicle is experiencing lateral roll 
movement. 
A roll attitude adjusting component 36a is shown in the centre of the 
transverse rod 35. The function of this component is to provide a 
mechanism which can alter the attitude of the vehicle about the roll axis 
to compensate for wheel displacements caused by, for example, load changes 
on the longitudinal torsion bars due to the roll moments produced during 
cornering. Typically, the roll attitude adjuster component 36a comprises a 
housing which can rotate with reference to the link 35 and can be similar 
in construction to devices commonly known as screw jacks or turn buckles. 
The rod 35 is normally discontinuous with a gap between the adjacent ends. 
The adjacent free ends so formed are threaded in opposite senses and the 
roll attitude adjusting housing cylinder 36a is provided with similar 
appropriate internal threads to engage the threads on the rod ends. 
When the housing cylinder 36a is turned, this causes the overall length of 
the rod 35 to be increased or decreased depending upon which way the 
cylinder 36a is turned relative to the rods 35. If the overall length of 
the rod 35, is reduced then the left side of the vehicle will be lowered 
and the right side will be raised, thereby leaning the vehicle to the 
left. If the length is increased then the left side of the vehicle will be 
raised and the right side will be lowered, thereby leaning the vehicle to 
the right. Active versions of the proposed suspension system can therefore 
be constructed, incorporating the above mechanism, to reduce, negate or 
even reverse vehicle roll. The rod length being appropriately adjusted by 
rotating the housing 36a which can be effected electrically, hydraulically 
or mechanically according to known ways and from remote locations. This 
can be effected by an electronic control mechanism which receives a signal 
indicating the required attitude of the vehicle body and a programme to 
effect adjustment of the housing cylinder position as required. 
While the inclusion of the roll attitude adjuster 36a raises or lowers one 
side of the vehicle in relation to the other, it is unable to directly 
adjust the height and level attitude of the entire vehicle. In the context 
of commercial vehicles, which are subject to large load weight changes 
resulting from cargo being introduced or removed, it is sometimes useful 
to include one or more height or attitude adjustment devices in the rear 
(or front, or side) torsion bars. Typically the height and attitude 
control could be incorporated in any of the torsion bars and would consist 
of a component 36b, 36c, 36d and 36e shown in FIG. 2a usually located at 
one end of at least one torsion bar which can rotate the bar to tighten or 
relax depending on whether there was a requirement for additional height 
or otherwise. The turning adjustments can be driven electrically, 
hydraulically or mechanically under manual or electronic control to adjust 
and trim the vehicle height according to the requirements at any given 
time. Various kinds of adjustment means are typically seen in vehicles 
fitted with conventional torsion bars, although these are not normally 
powered for height changes. An alternative method of effecting height and 
attitude changes is to locate a component similar in construction to the 
roll attitude adjuster 36a in the appropriate linking such as links 19, 
20, 21, 22 which effectively lengthens or shortens these linkages thereby 
changing the height and/or attitude of the vehicle. 
Referring now to FIG. 2B of the drawings, there is depicted a further 
modification of the suspension system previously described. In this 
system, the chassis 5 and the wheels 1, 2, 3 and 4 are of the same 
construction and are relatively arranged as previously discussed with the 
respective wheels being connected to the chassis 5 by wishbone 
configurations 7, 8, 9 and 10. The transfer of load between the respective 
wheels and the chassis 5 are carried out by individual torsion bar members 
102, 103, 105 and 106 connected between the respective wishbone assemblies 
and the body with each torsion bar being individually anchored to the 
body, such as to the anchor blocks 104 and 107 respectively. In this way, 
the weight of the chassis and load carried thereby is transferred directly 
from the chassis to each of the wheels independently, thus, resolving the 
forces developed in the respective torsion bars directly and individually 
into the vehicle chassis 5. 
In addition, torsion bars 13, 14, 17 and 18 are provided and individually 
mounted in the same manner as previously described with respect to FIG. 1 
and FIG. 2A, with the torsion bars 17 and 18 being interconnected by the 
gear unit 28 and the torsion bars 13 and 14 interconnected by a gear unit. 
The construction and interconnection of the respective torsion bars with 
the gear units 27 and 28 is identical to that previously described with 
reference to FIG. 2A and shall not be described in more detail here. 
Similarly, the gear assemblies 27 and 28 are interconnected by a linkage 
system 116 which is again of identical construction to that previously 
described with respect to FIG. 2A and 3 of the drawings. 
In the construction above described with respect to FIG. 2B, the torsion 
bars 102, 103, 105 and 106 may be of any known form provided the forces 
are resolved directly into the vehicle body and not transferred from one 
wheel to the other. Further, these torsion bars provide the necessary 
support for the weight of the vehicle and provide bounce and pitch 
resilience to the vehicle. The longitudinal torsion bars 13, 14, 17 and 18 
provide the resistance to body roll while resistance to axle articulation 
is only derived by the front and rear individual torsion bars and not the 
roll control torsion bars 13, 14, 17 and 18, thus resulting in a smaller 
variation in wheel loading during articulation compared to that of a 
standard vehicle with conventional stabiliser bars. 
Referring to FIG. 4 of the drawings wherein there is depicted an 
alternative form of interconnection between the respective torsion bars 
extending laterally and longitudinally of the vehicle chassis. The 
construction and layout of the basic chassis and the respective wheels and 
associated wishbone suspension system are the same as that previously 
described with reference to FIG. 1, and where appropriate, the same 
reference numerals have been applied in FIG. 4 but the general description 
of the arrangement of these components will not be repeated herein with 
respect to FIG. 4. The difference in the mechanism as shown in FIG. 4 
relates to the interconnection between the respective torsion bars which 
in FIG. 2A is based on a arrangement of gears that are replaced in the 
embodiment shown in FIG. 4 by a mechanical linkage system which will be 
now described in detail. 
As seen in FIG. 5 which is an enlarged view of portion of the torsion bars 
17 and 18, and the alternative interconnecting mechanism 40. The 
respective torsion bars 17 and 18 are provided with a rigid vertically 
projecting stubs 41 and 42 respectively, each of which is connected, with 
an end of the respective arm 43 and 44. The connection between the 
respective stubs and the arms are by way of a conventional ball and socket 
connection 50 and 51 to allow relative rotation therebetween and/or 
relative tilting or angular displacement. The other end of each of the 
arms 43 and 44 are pivotly connected to the end of the rod 61 by the pivot 
pin 52. 
The above construction operates such that, if the torsion bar 18 were to 
rotate in the clockwise direction, as a result of an upward movement of 
the front wheel 1 with respect of the chassis 5, then the stub 42 would 
similarly rotate in a clockwise direction thereby causing the arm 44 to 
push on the rod 61 to tend to align the arm 43 with the rod 61. This in 
turn will push on the arm 43 and rotate the torsion bar 17 in an 
anticlockwise direction. Thus it will be seen that the link mechanism as 
shown in FIGS. 4 and 5 produces the same effect as the bevel gear assembly 
described with respect to the rear lateral mechanical coupling means in 
FIG. 1. 
This suspension system as described with reference to FIGS. 4 and 5 allows 
the transverse torsion bars at the front and rear of the vehicle to 
counter rotate freely, as in vehicle body roll and axle articulation, but 
effectively prevents the motion of the central connection of the 
transverse torsion bars when a parallel motion of the wheels, as in bounce 
or pitch, occurs. In this way the front and rear transverse torsion bars 
support the load of the vehicle and provide resistance to bounce and pitch 
motions only. 
Neither the, longitudinal or transverse torsion bar systems, provide any 
axle articulation resistance resulting in a constant wheel loading during 
articulation. As both the transverse and longitudinal systems are totally 
independent in their operation it is possible to tune the vehicle 
independently for roll, pitch and bounce resistance. 
Referring to FIG. 4, the central pivot mounted link 60 is connected at one 
end to the link 61 which is connected to the mechanism 40 detailed in FIG. 
5. The other end of link 60 is connected to link 62 which is connected to 
the mechanism 66 which is the same as mechanism 40 in function and 
construction previously described. 
When the wheels on the left hand side of the vehicle are lowered relative 
to the body, as when the vehicle turns to the left, the stubs 41 and 42 on 
the ends of torsion bars 17 and 18 move left which in turn move the links 
43 and 44 left and thereby displacing the link 61 to the left as well. 
This motion is reversed by link 60 to move link 62 to the right and the 
corresponding links and stubs of mechanism 66 to the right. This results 
in a lowering of the wheels on the right hand side of the vehicle and 
therefore a resistance to roll of the body. The torsional stiffness of the 
torsion bars 13, 14, 17 and 18 influencing the amount of roll. 
In the case when wheel 1 is raised relative to the body and wheel 4 is 
lowered relative to the body the stub 42 moves right and stub 41 moves 
left. This forces the common end of links 43 and 44 to move towards the 
rear of the vehicle and not change the lateral position of link 61. No 
significant forces are generated in the longitudinal torsion bars. In this 
way the above described mechanism only provides resistance to roll motions 
of the body relative to the wheels. 
FIG. 4 also shows a mechanism s as previously described with reference to 
FIG. 5 used as the connecting means for the transverse torsion bars 
connecting the two front wheels and as the connecting means for the 
transverse torsion bars connecting the two rear wheels. Its operation is 
similar to that of the mechanism 40 described above except that the motion 
of pivot pin 52 shown in FIG. 5 is constrained to one in the lateral 
direction by the slot 75 respectively. 
Referring now to FIG. 6 of the drawing there is depicted therein a vehicle 
body and suspension system with the individual components thereof 
represented in the same manner as described previously with respect to 
FIG. 2. However in this vehicle there are three longitudinally spaced 
axial assemblies providing a six wheeled vehicle, as compared with the 
more conventional four wheeled vehicle. In FIG. 6 the front of the vehicle 
is represented at the upper end of the page with the steerable front 
wheels inclined to the left, being the position occupied for the vehicle 
to make a left hand turn. 
The front wheels 1 and 2 and the suspension system connecting same to the 
chassis 5 is identical to that previously described with respect of FIG. 
2A and have the same reference numerals applied thereto, however, for 
simplicity the detailed description thereof will not be repeated but 
reference may be made to that previous description in respect of FIG. 2A 
of the drawings. Also, the intermediate pair of wheels 3 and 4 in FIG. 7 
correspond to the rear wheels 3 and 4 as previously described with 
reference to FIG. 2 and the suspension systems thereof are also the same 
as previously described. Further, the rear set of wheels 3a, 4a in FIG. 6 
and the respective suspension systems are the same as the intermediate 
wheels and suspension and as that previously described with reference to 
rear wheels 3 and 4 in FIG. 2A and again will not be further described in 
detail. 
The arrangement and interaction of the torsion bars extending in the 
longitudinal direction between the front the intermediate wheels is the 
same as previously described with respect of the front and rear wheels in 
relation to FIG. 2A. Also the arrangement of the longitudinal torsion bars 
between the intermediate wheels and the rear wheels of the six wheels 
vehicle are as previously described with reference to the front and rear 
wheels in FIG. 2A. Further the arrangement of bevel gear trains between 
the torsion bars 17a and 18a and between 13a and 14a are constructed and 
operates in the identical manner to that previously described with respect 
of FIG. 2A. 
However the mechanisms interconnecting the front wheel transverse torsion 
bars 11 and 12 as shown in FIG. 6 is not the same as that previously shown 
in respect of FIG. 2A, however it is the same as that previously described 
with respect to the interconnecting of the longitudinal torsion bar 
members as shown in FIG. 2A. This mechanism is also used in 
interconnecting the intermediate transverse torsion bar 15, 16 and is also 
used in interconnecting the transverse torsion bars 15a, 16a of the rear 
wheel assemblies. 
It is to be noted however, that in contrast to the previous description 
with respect to FIG. 2 the bevel gear assemblies previously employed in 
respect of the longitudinally extending torsion bars are now incorporated 
to provide the interconnection between each of the front intermediate, and 
rear transverse torsion bar assemblies 71, 72 and 74 respectively. Also, 
in the embodiment shown in FIG. 6, there is a transfer rod 70 
interconnecting the gear assembly 71 of the front wheels with the gear 
assembly 72 of the intermediate wheel assembly, and a further transfer rod 
73 interconnecting the transverse gear assembly 72 of the intermediate 
wheels with the transverse gear assembly 74 of the of the rear wheel 
assembly. 
The function and operation of such transfer rods interconnecting the 
respective gear assemblies has previously been described with respect to 
FIG. 2A and the same function is performed when applied to the six wheel 
vehicle. However it will be recalled, as previously described, the 
transfer bar interconnecting the gear assemblies 32a and 32b as shown in 
FIG. 3 are arranged so that they are connected to the upper side of the 
gear assembly on one side of the vehicle and the lower side of the 
assembly on the opposite side of the vehicle. Thus the transfer rod 70 
extending between the transverse front gear assembly 71 and the transverse 
intermediate gear assembly 72, connects the top of the gear assembly 71 at 
the front of the vehicle to the top of the gear assembly 72 of the 
intermediate wheel assembly. However the transfer rod 73 extending from 
the transverse gear assembly 72, on the intermediate wheel assembly, to 
the gear assembly 74 on the rear wheel assembly, extends from the 
underside of the intermediate gear assembly 72 to the top of the rear gear 
assembly 74 at the rear wheel assembly. 
In the construction shown in FIG. 8, the basic layout of the vehicle 
chassis and suspension is as has previously been described with respect to 
FIG. 4 of the drawings, with the change that the mechanical link between 
the longitudinal torsion bars on either side of the chassis is now in the 
form of a hydraulic link. 
In the construction shown in FIG. 8, each of the arms 61 previously 
described with respect to FIG. 5, are extended to pass through a double 
acting hydraulic cylinder unit 80a, 80b with a piston mounted on the arm 
61 to move in unison therewith. The arm 61 extends through each end of the 
cylinder 80a, 80b so that the effective area of the piston 86a, 86b 
exposed to fluid on either side is equal. 
The two laterally spaced double acting cylinders 80a and 80b have 
respective chambers, 85a and 85b and 86a and 86b arranged so that the 
inner chamber 85a of the left hand double acting cylinder 80a is connected 
to the outer chamber 86b of the right hand cylinder 80b, similarly the 
inner chamber 86a of the right hand cylinder is connected to the outer 
cylinder 85b of the left hand cylinder. These hydraulic interconnections 
being made by conduits 89 and 90 respectively. 
Thus, as previously described with reference to FIG. 3 of the drawings, 
when the vehicle is turning to the left at a reasonable road speed, the 
vehicle chassis will tend to roll towards the right hand side causing a 
twisting action of both the torsion bars 13 and 14, so as to move the 
piston in the right hand cylinder 80b towards the left and the resulting 
fluid displacement will cause the piston in the left hand cylinder 80a to 
move to the right. Thus there is a load applied to the torsion bars 17 and 
18 which will also lower the left hand side of the vehicle thus, 
controlling and substantially eliminating roll of the vehicle chassis 
during cornering operations. 
FIG. 9 is a variation on the six wheel vehicle construction as previously 
described with respect to FIG. 7 and has been modified to operate using 
hydraulic cylinders in the same manner as previously described with 
reference to FIG. 8. In FIG. 9, the hydraulic cylinders 80a and 80b are 
constructed and interconnected to operate in the same manner as they did 
in FIG. 8. Also, the additional hydraulic cylinders 90a and 90b cooperate 
with gear assemblies 28.sup.1 and 27.sup.1 are also arranged to function 
the same as cylinders 80a and 80b in FIG. 8. 
However, in the construction shown in FIG. 9, further double acting 
hydraulic cylinders are provided to interconnect the gear units 91 and 92 
which function the same as the gear units 71 and 72 in FIG. 6. However, in 
this application, the double acting hydraulic cylinders 93 and 94 are 
interconnected to move in unison in the same direction, thus function the 
same as the link 70 in FIG. 6. 
Further, the hydraulic cylinders 95 and 96 associated with the gear units 
92 and 97 are interconnected by the lines 98 and 99 to move in opposite 
directions so that they induce the gear units 72 and 74 to rotate in 
opposite directions. Thus, it is seen that the cylinders 95 and 96 and 
lines 98 and 99 function the same as the rod 73 in FIG. 6. 
The suspension system of the six wheeled vehicle as previously described 
herein, enables driving ground engagement to be maintained between all six 
wheels and the ground being traversed substantially irrespective of the 
degree and direction of undulation of the ground surface. As will be 
appreciated, six wheeled vehicles are particularly constructed for 
carrying relatively heavy loads in off road situations where a 
substantially high degree of articulation of the respective wheels is 
required without the loss of traction between any of the wheels. This 
problem is particularly prevalent in currently known six wheel drive 
vehicles where ground contact of at least some of the wheels frequently 
arises when traversing severely undulating terrain and the resulting 
increase in load carried by the wheels remaining in contact with the 
ground can lead to bogging the vehicle where the ground surface is sandy, 
powdery or wet. 
Referring now to FIG. 7 of the drawings, the representation B of the 
vehicle represents the traversing of a lowly undulating surface wherein 
difficulty is not particularly experienced in maintaining ground contact 
of all wheels. However, it must be appreciated that in some terrains, it 
is possible for the wheels on one side of the vehicle to be as shown in 
representation B, but the wheels on the other side of the vehicle may be 
traversing a severely undulating surface such as shown in representation A 
and C. 
The load distribution and sharing which is achieved with the suspension 
system as herein described with reference to FIGS. 6 and 9, enables all 
six wheels to be maintained in ground contact with the load of the vehicle 
being distributed between all six wheels to thereby maintain traction and 
reduce or eliminate the risk of bogging of the vehicle due to some of the 
vehicles losing load induced contact with the ground. 
The invention being thus described, it will be obvious that the same may be 
varied in many ways. Such variations are not to be regarded as a departure 
from the spirit and scope of the invention, and all such modifications as 
would be obvious to one skilled in the art were intended to be included 
within the scope of the following claims.