Motor vehicles – Special wheel base – With means for changing number of supporting wheels – or for...
Patent
1997-04-24
2000-05-23
Dickson, Paul N.
Motor vehicles
Special wheel base
With means for changing number of supporting wheels, or for...
180242, 280638, 2801492, B62D 2114
Patent
active
060655569
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention relates to motor vehicles and particularly, though not exclusively to vehicles capable of performing heavy duty work functions such as loading and more particularly relates to improvements in the construction, operation and stability of such vehicles. More particularly the invention relates to a variable geometry vehicle wherein at least the wheel base can be extended to provide a counterbalance for loading which would otherwise tend to destabilise the vehicle. Whilst the present invention will be described primarily with reference to skid steer vehicles, it will be understood by persons skilled in the art that the invention is not limited to vehicles able to perform loading functions but is applicable to a wide variety of vehicles capable of performing functions other than loading.
PRIOR ART
There are in existence a number of different types of loaders each designed to perform the functions of lifting and loading. The configurations of the known loaders are largely dictated by the function each performs. Among the known loaders are skid steer loaders, fork lifts, front end loaders and backhoes with the latter having front end loading capability.
Skid steer loaders are well known vehicles which generally comprise, a vehicle body of monocoque construction having drive means mounted in or on the body, two sets of wheels attached to and supporting the body and a work implement such as a front end loader assembly attached to the vehicle body. The skid steer loader was developed as a very compact, relatively light and very manoeuvrable vehicle. It is therefore able to be transported in small tippers to building and work sites and is very useful in confined areas providing reasonable pushing and loading ability. One such skid steer loaders having a very short wheel base has proven to be successful as an easily transportable earth mover capable of detachably receiving a variety of work implements and in being able to do so replacing larger and more expensive machines eg. (backhoes, diggers, etc.) Despite these advantages these skid steer loaders are known to be inherently unstable in operation. As they are short wheel base vehicles, they rely to some extent for operational stability on the weight of the drive assembly, particularly the motor, which is generally mounted rearward to provide counterbalancing for the front end work implement and, in view of the overall geometry of the machine, it must therefore adopt a balance compromise. Thus, if the rear of the machine is weighted too heavily for the purpose of allowing a large payload bucket lift, the machine would rear up trying to negotiate minor slopes and obstructions particularly when the bucket is empty. Alternatively, if the rear of the machine was weighted too lightly, it would not lift a reasonable payload and would be susceptible to forward rotation about the front wheels.
Previously, skid steer loaders have needed to be rear heavy to lift weights and although not designed specifically for this purpose, to allow the machine to climb steep slopes backwards where necessary, and to allow pick up of a reasonable payload in the bucket during each lift. Rear weighting has thus proven to be the best possible compromise in a very short wheel base machine. Thus, when negotiating very steep slopes for safety the existing short wheel base skid steer loaders are preferably reversed up slopes where practical but are limited to only moderate slopes when travelling forward and when the bucket is empty particularly when the bucket is in the air.
The dynamic forces distributed over this machine in use are quite complex and along with the short wheel base contribute to the machines inherent instability. The dynamic loads on the existing machines vary according to a number of factors taken separately or in combination with other factors which include; the speed at which the machine is driven during operation, the load carried in the loading assembly bucket, the height of the bucket lift, the roughness of the terrain on which the loader
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Dickson Paul N.
Van William Concepts Pty. Ltd.
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