Craig, Stone
David, Mcconnell
Ian
| 1. | * A high speed engineering vehicle, said high speed engineering vehicle including a suspension system for suspending the mass of the body of the vehicle on the axles of the vehicle wherein said suspension system includes a suspension unit which connects onto the chassis of the vehicle and an axle of the vehicle, said suspension unit including fluid medium to provide both springing and damping action. |
| 2. | The high speed engineering vehicle as claimed in Claim 1 wherein said suspension unit includes a compressible fluid medium to provide both springing and damping action. |
| 3. | The high speed engineering vehicle as claimed in Claim 2 wherein said suspension unit includes a pressurised compressible fluid medium to provide both springing and damping action. |
| 4. | The high speed engineering vehicle as claimed in any one of Claims 1 to 3 wherein said fluid medium includes a silicone based liquid. |
| 5. | The high speed engineering vehicle as claimed in any one of Claims 1 to 4, said suspension unit providing variable rate spring characteristics wherein a nonlinear relationship between deflection force and suspension deflection is achieved. |
| 6. | The high speed engineering vehicle as claimed in Claim 5, said suspension unit providing progressive rate springing characteristics wherein the deflection force required for a given unit of deflection of the suspension increases as the suspension deflection increases. |
| 7. | The high speed engineering vehicle as claimed any one of Claims 1 to 6 wherein the vehicle has variable ride height capability achieved by varying the fluid pressure within the suspension unit. |
| 8. | The high speed engineering vehicle as claimed in any one of Claims 1 to 7, said suspension system including a linkage arrangement for connecting and locating the axles of the vehicle relative to the chassis of the vehicle, said linkage arrangement including a plurality of locating arms which connect with mounting points on the axle and extend from said mounting points on said axle to mounting points on the chassis of the vehicle. |
| 9. | The high speed engineering vehicle as claimed in Claim 8, wherein said linkage arrangement includes a laterally extending locating arm which connects the axle to the chassis of the vehicle to provide lateral location of said axle relative to the chassis of the vehicle. |
| 10. | The high speed engineering vehicle as claimed in Claim 8, said suspension system including a front suspension system for suspending the body of the vehicle relative to a front axle of the vehicle, wherein said front suspension system includes a linkage arrangement for connecting and locating the front axle of the vehicle relative to the chassis of the vehicle, said linkage arrangement including a plurality of locating arms which connect with mounting points on the front axle and extend rearwardly from said mounting points on said front axle to mounting points on the chassis of the vehicle. |
| 11. | The high speed engineering vehicle as claimed in Claim 10 wherein said linkage arrangement includes a pair of locating arms which connect with upper mounting points located on the axle housing of the front axle and which extend rearwardly from said upper mounting points to mounting points on the chassis of the vehicle and a pair of locating arms which connect with lower mounting points located on the axle housing of the front axle and which extend rearwardly from said lower mounting points to mounting points on the chassis of the vehicle. |
| 12. | The high speed engineering vehicle as claimed in Claim 10 or 1 1 wherein said linkage arrangement for the front suspension further includes a laterally extending locating arm which connects said front axle to said chassis of the vehicle to provide lateral location of said front axle relative to the chassis of the vehicle. |
| 13. | The high speed engineering vehicle as claimed in any one of Claims 8 to 12, said suspension system including a rear suspension system for suspending the body of the vehicle relative to a rear axle of the vehicle, wherein said rear suspension system includes a linkage arrangement for connecting and locating the rear axle of the vehicle relative to the chassis of the vehicle, said linkage arrangement including a plurality of locating arms which connect with mounting points on the rear axle and which extend forwardly from said mounting points on said rear axle to mounting points on the chassis of the vehicle. |
| 14. | The high speed engineering vehicle as claimed in Claim 13 wherein said linkage arrangement includes a pair of locating arms which connect with upper mounting points located on the axle housing of the rear axle and which extend forwardly from said upper mounting points to mounting points on the chassis of the vehicle and a pair of locating arms which connect with lower mounting points located on the axle housing of the rear axle and which extend forwardly from said lower mounting points to mounting points on the chassis of the vehicle. |
| 15. | The high speed engineering vehicle as claimed in Claims 13 or 14 wherein said linkage arrangement for the rear suspension further includes a laterally extending locating arm which connects said rear axle to said chassis of the vehicle to provide lateral location of said rear axle relative to the chassis of the vehicle. |
| 16. | The high speed engineering vehicle as claimed in any one of Claims 1 to 15 wherein said high speed engineering vehicle includes a means to lock the suspension system to limit suspension movement. |
| 17. | The high speed engineering vehicle as claimed in Claim 16 wherein said means to lock the suspension system includes an extendible member, one end of said extendible member being connected to the chassis of the vehicle and another end of said extendible member capable of extending to a position such that it contacts an axle of the vehicle and limits the movement of the suspension. |
| 18. | The high speed engineering vehicle as claimed in Claim 17 wherein said extendible member is hydraulically activated. |
| 19. | The high speed engineering vehicle as claimed in any one of Claims 1 to 18 wherein said high speed engineering vehicle is capable of performing front end loader and/or backhoe operations. |
| 20. | The high speed engineering vehicle as claimed in any one of Claims 1 to 19 wherein said high speed engineering vehicle is a multipurpose engineering vehicle which can be adapted by means of various attachments to perform a range of engineering tasks. |
FIELD OF THE INVENTION
This invention is in relation to engineering vehicles and in particular, heavy duty engineering vehicles for either military or civilian applications. The present invention provides an improved engineering vehicle with greatly enhanced on-road and off-road performance characteristics. BACKGROUND TO THE INVENTION
Engineering vehicles, such as front-end loaders and backhoes, are used in a variety of applications for digging, loading and lifting operations. In military applications such vehicles are used, for example, in the digging of trenches, road construction and in building bridges. In civilian applications such vehicles may be used by the single-man building contractor and large scale construction companies alike. Similarly, Government bodies and councils also use front-end loaders and backhoes for their public works, such as in road construction and drainage and sewage repairs.
In military applications it is desirable to be able to deploy engineering vehicles as quickly and as efficiently as possible, often covering large distances in the process. In the situation of the single-man building contractor, generally job sites can be anywhere, thus often requiring an engineering vehicle such as a front-end loader/backhoe to be moved over large distances to the various work sites. A similar situation exists for Government organisations and in particular rural councils wherein one council can be responsible for a relatively large area, where engineering vehicles may be required to operate at sites which are significant distances apart. However due to their specific nature and function, engineering vehicles such as front-end loaders and backhoes have limited on-road capabilities. Therefore where such vehicles are to perform tasks at a variety of sites separated by relatively large distances it is usual to employ a further vehicle to transport the engineering vehicle to the various work sites. Thus, due to the limitations of existing engineering vehicles it has been necessary to rely upon a further vehicle to transport the engineering vehicle from one site to the next. This adds considerably to the capital costs by requiring the purchase and
maintenance of a vehicle to perform this transportation function. For example, with front-end loaders/backhoes, it has been necessary for the users of these engineering vehicles to use a truck to tow the front-end loader/backhoe vehicle or alternatively a truck and a trailer arrangement to carry the vehicle. Thus whilst a front-end loader/backhoe can be transported from one location to another in a realistic time frame, it is necessary to provide a further vehicle in order to do so and the expense of providing a truck, and also in most cases a trailer, often more than doubles the cost of purchasing a front-end loader or backhoe alone. Further to the significant increase in capital costs involved with providing a suitable transportation means, there are the additional costs of running and maintaining the additional vehicles. Furthermore, in military applications it is often impractical in times of conflict to rely upon a further vehicle to transport the engineering vehicle. Hence in such situations it is particularly desirable for the engineering vehicle to be self-deployable. A further limitation of existing engineering vehicles is their inability to traverse off-road terrain at relatively high speeds. This ability is particularly desirable in engineering vehicles for military purposes, where it is particularly desirable and advantageous in times of conflict to be able to move and deploy the engineering vehicle in the shortest possible time. Often it is necessary to cross rugged terrain where there are little or no roads in order to reach the desired site. However known engineering vehicles are unable to cross rough terrain with levels of stability and controllability to enable the vehicle to travel at desirable speeds. Moreover existing engineering vehicles afford poor levels of ride comfort to the passenger/s when covering such rough terrain. Again, in military applications, where it is often necessary to be able cover large distances across country where roads are either poor or non-existent and the terrain is rough, good levels of ride comfort are required to ensure that passengers are not fatigued or injured.
Thus the present invention is directed to overcoming some of the problems and limitations associated with existing engineering vehicles and provide an improved engineering vehicle with greatly enhanced on-road and off-road performance characteristics.
SUMMARY OF THE INVENTION
To this end the present invention provides a high speed engineering vehicle, said high speed engineering vehicle including a suspension system for suspending the mass of the body of the vehicle on the axles of the vehicle wherein said suspension system includes a suspension unit which connects onto the chassis of the vehicle and an axle of the vehicle, said suspension unit including a fluid medium to provide both springing and damping action.
It should be noted that the suspension system according to the present invention can be adapted to any form of engineering vehicle where it is desirable that the vehicle have enhanced stability and control to enable it to travel at relatively high speeds. For example it can be adapted to vehicles such as a front end loader and/or backhoe, a crane or a fork-lift. Also the engineering vehicle may be a multi-purpose engineering vehicle which can be adapted by means of various attachments to perform a range of engineering tasks such as digging, loading and lifting.
The suspension units, also known as liquid spring struts, provide a compact, robust suspension unit that fully integrates spring and damping functions in a compact strut unit. One manufacturer of such suspension units is Davis Technologies International, Inc. of U.S.A. The suspension units used in the present invention rely upon a fluid medium and act as both a spring and a damper for absorbing and dissipating energy. Preferably the suspension unit includes a compressible fluid medium, with a preferred medium being a silicone based fluid. It is further preferable that the fluid medium be pressurised within the suspension unit. Advantageously, the unique suspension system of the engineering vehicle provides a compact, robust suspension system which has good springing and damping characteristics and provides long suspension travel. The engineering vehicle is thus ideally suited to heavy duty applications such as those required by the military. The suspension system enables the engineering vehicle to travel on roads at speeds not thought possible with conventional engineering vehicles, such as conventional front-end loaders and backhoes. The vehicle according to the present invention is capable, under its own power,
of speeds greater than 60 km/hr and typically the vehicle is capable of averaging speeds around 80 to 100 km/hr. Thus the vehicle can cover large distances in a time frame which is virtually equivalent to the time currently required to transport conventional engineering vehicles by means of additional transportation vehicles. This also results in a significant reduction in the normally high capital and labour costs associated with such engineering vehicles.
Also advantageously, the off-road characteristics of an engineering vehicle according to the present invention are greatly improved over previous engineering vehicle designs. The suspension system according to the present invention is capable of long travel. This enables traction and vehicle stability to be maintained over rough terrain where there are great surface variations.
Preferably the suspension unit also provides variable rate springing characteristics such that a non-linear relationship between deflection force (force required to deflect the suspension) and suspension deflection (travel) is achieved. It is further preferable for the suspension unit to provide progressive rate springing characteristics wherein the deflection force required for a given unit of deflection of the suspension increases as the suspension deflection increases.
It is also preferable for the vehicle to have variable ride height capability, provided by varying the fluid pressure within the liquid spring strut suspension units. By varying the fluid pressure in the suspension units the vehicle ground clearance can be increased for off-road operation, thus enhancing the vehicle's cross-country ability.
The present invention, as result of the good springing and damping characteristics and long suspension travel, also provides the further advantage of affording enhanced ride comfort to the passengers of the vehicle.
The engineering vehicle of the present invention has particular application in military roles where its excellent on-road and off-road capabilities are particularly advantageous in times of conflict. However the capabilities of the engineering vehicle are also well suited to civilian applications.
It should be noted that the suspension system of the present invention can be adapted to both "live" axle suspension designs and "independent"
suspension designs. With live axle designs a member (commonly an axle) runs between and links the wheels on opposing sides of the vehicle. The suspension system can also be adapted to independent suspension designs wherein there is no common linkage member between the wheels on opposing sides of the vehicle and hence each wheel is suspended independently of its opposing wheel on the opposite side of the vehicle.
The suspension system of the present invention provides significant advantages in the suspension of an engineering vehicle over other forms of suspension. For example a suspension system relying upon leaf springs and separate dampers requires a much larger packaging volume, in the sense that the chassis of the vehicle needs to extend beyond the axle to provide a mounting point for one end of the leaf spring. Furthermore leaf spring arrangements limit the steering lock available and hence reduce the manoeuvrability of the vehicle. Leaf springs also generate large bending moments on the axle housing. A leaf spring and damper arrangement is also relatively heavy and requires high maintenance effort, particularly in heavy duty applications such as in engineering vehicles. A suspension system which relies upon coil springs and separate damper units is also relatively heavy in comparison with the strut units utilised in the present invention. Coil spring and damper arrangements also pose packaging difficulties due to the large volume requirement of the two components, particularly in heavy duty applications such as in engineering vehicles. Moreover correct mounting of the coil spring and damper are critical since proper alignment needs to be maintained in order to prevent dislodgment of the coil spring unit. Thus installation and maintenance of such suspension arrangements are more difficult than with the suspension units of the present invention. Air bags are also difficult to install and also require large packaging volume. Furthermore air bags are prone to damage and hence are unsuitable for off road use such as military applications. They also provide limited suspension travel, hence limiting off-road capabilities. Additionally, the suspension system of the high speed engineering vehicle preferably has a suspension linkage arrangement to locate the axles of the vehicle relative to the vehicle chassis. Preferably the linkage arrangement
includes a plurality of locating arms which connect with mounting points on the axle and extend from said mounting points on said axle to mounting points on the chassis of the vehicle. The linkage arrangement may include locating arms which are arranged substantially parallel to the centre-line of the vehicle. Alternatively the locating arms may be angled relative to the centre-line of the vehicle to provide the required location of the axle relative to the chassis. It should be understood that the exact positioning and direction of the locating arms is influenced by factors of the engineering vehicle design such as the available clearance for the linkages and suitable mounting points on the vehicle chassis and axles. Hence the positioning and direction of the locating arms can vary depending upon the design of the engineering vehicle and the particular operational requirements whilst still remaining within the scope of the present invention.
It is also preferable for the linkage arrangement to include a laterally extending locating arm which connects the axle to the chassis to provide lateral location of the axle relative to the chassis of the vehicle.
Whilst the linkage arrangement is not essential to the invention, the elements of the arrangement assist in the high speed engineering vehicle attaining high speeds on all types of roads such as on dirt tracks and cross- country.
Also the high speed engineering vehicle preferably includes a means to lock the suspension system to limit suspension movement. This enables suspension movement to be limited whilst the engineering vehicle is performing operations such as digging and lifting. Preferably the means to lock the suspension system includes an extendible member, one end of the extendible member being connected to the chassis of the vehicle and another end of said extendible member capable of extending to a position such that it contacts an axle of the vehicle to thereby limit the movement of the suspension. It is further desirable that the extendible member be hydraulically activated.
BRIEF DESCRIPTION OF DRAWINGS
The present invention will be better understood and appreciated with reference to the following description in relation to the accompanying drawings which illustrate a preferred embodiment of the invention. Figure 1 illustrates the preferred embodiment of a high speed engineering vehicle according to the present invention, the engineering vehicle being a front- end loader/backhoe.
Figure 2 illustrates a plan top view of the front axle of the high speed engineering vehicle. Figure 3 is a schematic plan view of the preferred front suspension linkage arrangement of the high speed engineering vehicle.
Figure 4 is a schematic plan view of the preferred rear suspension linkage arrangement of the high speed engineering vehicle.
Figure 5 is a schematic side view of the preferred front suspension linkage arrangement of the high speed engineering vehicle.
Figure 6 is a schematic side view of the preferred rear suspension linkage arrangement of the high speed engineering vehicle.
Figure 7 illustrates in more detail a preferred embodiment of the vehicle suspension lock system of the present invention. DESCRIPTION OF PREFERRED EMBODIMENT
Figure 1 illustrates a preferred embodiment of the high speed engineering vehicle which is generally marked 10 on this figure. In this example the high speed engineering vehicle 10 includes a front-end loader section 11 and a back hoe section 12. However, of course the high speed engineering vehicle 10 can have either a front-end loader section 11 or a backhoe section 12 independent of each other. It should also be noted that the suspension system according to the present invention can be adapted to any form of engineering vehicle where it is desirable that the vehicle have enhanced stability and control to enable it to travel at relatively high speeds. For example it can be adapted to vehicles such cranes and fork-lifts. Also the engineering vehicle may be a multi-purpose engineering vehicle which can be adapted by means of various attachments to perform a range of engineering tasks such as digging, loading and lifting.
It can be seen from the cut-away portion of the front wheel that the high speed engineering vehicle has a suspension system. With reference to Figures 1 and 2, the suspension system includes a suspension unit 15 which at each end connects onto the vehicle's chassis and axles 14. The preferred system is a unique liquid spring strut unit which utilises a system of valves and a liquid medium, preferably silicone, to act in a manner similar to a spring and damper arrangement. The liquid spring strut system is preferred since it is generally small in size and less packaging volume is required. Also, when compared to a separate spring and damper arrangement, the liquid spring strut system only requires a single bolt attachment. Furthermore the suspension unit provides both spring and damping characteristics in one integral unit.
The suspension unit 15 also preferably provides variable rate springing characteristics such that a non-linear relationship between deflection force (force required to deflect the suspension) and suspension deflection (travel) is achieved. It is further preferable for the suspension unit to provide progressive rate springing characteristics wherein the deflection force required for a given unit of deflection of the suspension increases as the suspension deflection increases.
A liquid spring strut is preferably applied onto each of the wheels of the high speed engineering vehicle at every wheel/tyre location (not shown).
As mentioned above the suspension system utilised in the present invention can be used with "live" axle designs, such as that depicted in the accompanying drawings, where a member (such as an axle) runs between and links the wheels on opposing sides of the vehicle. The suspension system can also be adapted to independent suspension designs wherein each wheel is suspended independently of the other vehicle wheels and there is no common linkage member between the wheels on opposing sides of the vehicle.
Additionally to assist the liquid spring strut suspension system the high speed engineering vehicle 10 has a linkage arrangement between the axles and the chassis of the vehicle. In the preferred embodiment of the invention the engineering vehicle includes a linkage arrangement affixed to both front and rear axles of the vehicle. The linkage arrangement preferably includes two lower
locating arms which connect to the axle, near the wheels, and to the chassis. The linkage arrangement also preferably includes two upper locating arms which also connect to the axle, either near the centre of the axle or the wheels, and to the chassis. As noted above the linkage arrangement may include locating arms which are arranged substantially parallel to the centre-line of the vehicle or which are angled relative to the centre-line of the vehicle. It is further preferable for the linkage arrangement of each axle to include a laterally extending linkage between the axle and chassis of the vehicle, also known as a pan hard rod. The linkage system assists in connecting the chassis to the axles and in preventing lateral movement of the same relative to each other.
Referring to Figures 3 and 5 the preferred linkage arrangement of the front suspension is depicted, with the direction of the front of the vehicle indicated. The preferred embodiment the front suspension linkage arrangement includes four rearwardly extending locating arms indicated by the reference numerals 21 & 22 which are pivotally connected to the chassis of the vehicle, and to the axle at lower and upper mounting points respectively on the axle housing. These locating arms 21 & 22 are also known as radius rods. The locating arms extend rearwardly from their respective front axle mounting points in a direction substantially parallel to the centre-line of the vehicle. There is one lower locating arm 21 and one upper locating arm 22 located on each side of the vehicle. The lower locating arms 21 are substantially parallel to each other and connect to the front axle housing at a mounting points on the axle housing which are located near the wheels and which lie below the axle. Similarly the pair of upper locating arms 22 are also substantially parallel to each other and connect to the front axle housing at a mounting points on the axle housing which are located near the wheels and which lie above the axle. In plan view the respective locating arms 21 & 22 located on each side of the axle are substantially co-planar. A laterally extending locating arm 23, also known as a panhard rod, is located forwardly of the front axle housing and links the front axle to the chassis of the vehicle with the rod connecting to the chassis via mounting 24. The locating arm 23 acts to provide lateral location of the front axle relative to the chassis.
Referring to Figures 4 and 6 the preferred linkage arrangement of the rear suspension is depicted, with the direction of the front of the vehicle indicated. The preferred embodiment the rear suspension linkage arrangement includes four forwardly extending locating arms, or radius rods, indicated by the reference numerals 31 & 32 which are pivotally connected to the chassis of the vehicle, and to the rear axle at lower and upper mounting points respectively on the rear axle housing. The locating arms extend forwardly from their respective rear axle mounting points in a direction substantially parallel to the centre-line of the vehicle. As with the front suspension arrangement there is one lower locating arm 31 and one upper locating arm 32 located on each side of the vehicle. The lower locating arms 31 are substantially parallel to each other and connect to the rear axle housing at a mounting points on the axle housing which are located near the rear wheels and which lie below the rear axle. Similarly the pair of upper locating arms 32 are also substantially parallel to each other and connect to the rear axle housing at a mounting points on the axle housing which are located near the rear wheels and which lie above the rear axle. In plan view the respective locating arms 31 & 32 located on each side of the axle are substantially co-planar. A laterally extending locating arm 33, or panhard rod, is located rearwardly of the rear axle housing and links the rear axle to the chassis of the vehicle with the rod connecting to the chassis via mounting 34. The locating arm 33 acts to provide lateral location of the rear axle relative to the chassis.
With reference to Figures 1 and 2, a steering box 13 is illustrated in relation to the front axle 14 and steers the front axles 14. Similarly, a four-wheel steering option (not shown) is also possible.
The high speed engineering vehicle can be either two-wheel drive or four-wheel drive, depending upon the travelling speed required or the terrain being traversed.
Preferably, the front 14 and rear axles have at each wheel location power operated drum brakes. Additionally, the axles are driven with a differential lock feature. By having the differential lock feature the mobility of the vehicle 10 in all terrains is greatly improved. Additionally these features assist in providing the
engineering vehicle 10 with superior front-end digging capabilities. Surprisingly, during digging the vehicle has more resistance to wheel slippage than conventional front-end loaders or backhoe vehicles.
Also, the high speed engineering vehicle preferably includes a unique vehicle suspension lock system. This system is used when the engineering vehicle is being used in digging, loading or lifting operations and it is desired to limit the vertical movement of the vehicle on its suspension.
In the embodiment of the front end loader/backhoe engineering vehicle depicted in the accompanying drawings the suspension lock system acts on the front axle of the engineering vehicle to limit the vertical movement of the vehicle on its suspension when the front-end loader bucket is being used. Thus when arriving at a work site the front suspension system can be isolated on the front axle via two hydraulically operated cylinders which can be controlled by the operator from within the cabin of the vehicle. This enables the engineering vehicle to commence front end loading operations quickly. The suspension limiting device acts to limit any bump travel hence controlling the depth of cut of the front-end loading bucket 11. This system primarily prevents the front of the engineering vehicle from moving vertically downward when performing digging operations which in turn assists the operator in accurately performing digging tasks with the front-end loader. The vehicle suspension lock is particularly important if the operator needs to excavate a trench within certain tolerance ranges. Figure 7 illustrates a preferred embodiment of the suspension locking system. The system consists of pressurised hydraulic rams 16 which are preferably located on either side of the front of the vehicle near the suspension units 15. The rams are attached onto the chassis, and when the vehicle suspension lock system is required to be engaged the rams 15 move vertically downward (due to hydraulic fluid) until each ram "bottoms out" onto the front axle 14. In particular, the ram pad 18 moves vertically downwards until it "bottoms out" onto front axle 14.
Once engaged, the axle on either side of the vehicle is prevented from moving vertically upward relative to the chassis of the vehicle and conversely the chassis of the vehicle is prevented from moving vertically downward relative to the axle. Once the vehicle suspension lock system is no longer required, the operator disengages the system which in turn causes the hydraulic rams 15 to move vertically upwards to their parking position, to allow once again, free vertical suspension movement at the front of the vehicle.
The vehicle suspension lock system assists the high speed engineering vehicle in performing accurate digging tasks which is essential in some digging applications; such as communication cable laying or pipe excavation.
It can be seen from Figure 1 that the high speed engineering vehicle 10 preferably has both front-end loading and backhoe functions. Furthermore because of the attachments of the front-end loader and backhoe apparatus the vehicle is capable of performing engineering functions such as fork-lift by utilising the front-end loader and/or backhoe and also lift objects as a crane by utilising the same apparatus. It is envisaged that other known systems can be attached to the high speed engineering vehicle in order to perform the above functions and other functions. Thus in summary the invention provides an engineering vehicle which is capable of achieving speeds higher than conventional engineering vehicles such as front loaders or backhoe vehicles and hence a vehicle which is capable of travelling reasonable distances in a commercially realistic time frame. The engineering vehicle of the present invention is far superior than any existing engineering vehicle, such as a front-end loader or backhoe, available on the market for speed and mobility over any terrain, including sealed and secondary roads, dirt tracks and cross-country. By comparison, it has been found that its cross-country ride is excellent when compared to conventional engineering vehicles. Also the vehicle dynamic characteristics while traversing over any of the above mentioned surfaces and relative speeds, are stable, predictable and controllable in terms of steering and handling characteristics.