Land vehicles – Wheeled – Running gear
Patent
1997-07-11
2000-07-11
English, Peter C.
Land vehicles
Wheeled
Running gear
280124116, 180 2407, 180348, 298 22R, B60G 902, B62D 6100
Patent
active
060860766
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to suspension systems and configurations for the main structural components of very large trucks of the type used in mining operations.
BACKGROUND OF THE INVENTION
There is much commonality between currently available large mining trucks made by different manufacturers and the following observations are generally applicable regardless of the truck manufacturer: weight. Typically the ratio of payload to empty vehicle weight is only about 1.4:1. This means that much of the cost of operating such trucks is related to moving the empty vehicle weight rather than the payload. of the truck. Typically 65% of the total width of a truck is taken up by the four rear tires. With present designs of truck this leads to a very narrow main frame for the truck and very high bending loads on the rear axle and rear wheel support systems. The narrow main frame causes shortage of space for maintenance of some components, high stress changes during cornering maneuvers, the need for vertically stiff rear suspension springs and design restrictions on the body. The net effect is high weight and cost for the main frame, the rear axle, the rear wheel support assemblies and the body. limited compared to the scale of the truck. Typically the maximum travel in the compression direction of the rear axle relative to the main frame is only of the order of 50 mm when loaded. This limited travel is a result of the need to achieve adequate roll stiffness from the two narrowly spaced rear spring units. heavy (e.g. 16.5 tons for the main frame of a truck with a payload rating of 172 tons), expensive to design, develop and manufacture, and prone to fatigue cracking. generally stiff member. This strength and stiffness is a consequence of the need for the body to withstand the shock loads applied during loading of large rocks by large excavators. points. For example at the rear pivot points, at two, four, six or eight points along the underside of the body and in some trucks also at forward extensions of the body which contact the main frame at points which are close to being above the line joining the centers of the front wheels. This system of supporting the stiff body causes high variations of stress levels in the main frame of the truck and the body as the truck traverses over uneven ground and during cornering. This feature causes fatigue problems, high design and fabrication costs and the need for considerable expenditure to limit the unevenness of the ground on which the trucks travel. main frame of the truck at points near to midway between the front and rear wheels. This causes very large bending loads to be applied to the main frame of the truck and requires that the main frame by very massive at the mid sections. It can also cause large stress changes in the body. turning maneuvers (frequent occurrences in typical mining operations), this causes severe scrubbing type wear of the tires due to the differential travel distance effect. Relative scrubbing between the two tires of a dual set is considered to contribute significantly to total wear of rear tires on large mining trucks. large variations in individual tire loads as the truck traverses uneven ground conditions. This arrangement also means that it is necessary to take considerable care in matching tire outside diameters and inflation pressures to minimize the unevenness in tire loads on level ground conditions. between the body and the ground is through a very indirect path which involves high bending loads in the body, the main frame of the truck, the rear axle housing and the rear wheel support systems. Furthermore these bending loads fluctuate greatly as the truck travels over uneven ground, during cornering and when the dump body is raised during unloading.
A typical very large mining truck is shown in FIG. 1 of the drawings of U.S. Pat. No. 5,385,391, and it will be noted that the frame structure is quite substantial and this results from the frame being required to bear the load supported by the body of the truck by contact b
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Bartley Francis Allen
Dickerson Alan William
Miller Darin Ross
Prem Hans
BHP Coal Pty Ltd.
English Peter C.
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