Presently known vehicles are very restricted with respect to performing satisfactorily over more than one operational environment. Existing wheeled vehicles operate with maximum efficiency on roads and highways but suffer a performance loss traveling off the road and are prone to immobilization in soft soils. Tracked vehicles perform well in most of the terrain conditions encountered off the road, have acceptable to marginal capabilities in soft soils depending on the track configuration, but fall short of wheeled vehicle performance on roads and highways fromthe standpoints of efficiency and accelerated track wear at higher speeds. Other highly-specialized vehicles designed primarily for superior performance in soft soils generally have little ability to travel on roads and highways, and involve the use of transporters for movements of any distance. The principal obstacle to achieving what might be termed "universal mobility" -- the ability to perform equally well over more than one operating environment -- with a single vehicle has been incorporating a capability for high performance in severe soft soil conditions. The movement of wheeled and tracked vehicles through unstable plastic, soft soils is generally not possible without substantial sinkage and slip. The resuling deformation of the material causes high mostion resistance and silp losses, degrading the efficency of the vehicle and making it prone to immobilization. The design steps which have customarily been takes to imtigate this condition have been in direct contradiction of those steps which are necessary to assure high performance on roads and highways. A more satisfactory solution could be realized by designing for efficent operation on improved surfaces -- roads and highways -- by provind for wheeled locomotion in that environment and incorporating a full capability for high performance in severe soft soil condition by employing a method of locomition -- utilizint the wheeled running gear -- which would result in performance equal or better than that of a tracked running gear.
It is therefor a primary object of this invetion to provide a vehicle having equally high performance when operated on roads and highways, irregular hard ground, and in soft soils and, particularily, a vehicle in which the running gear components employed for locomotion on improved surfaces -- roads and highways -- and hard irregular gournd are powered and operating in a efficeient mannor to provide locomotion in severe soft soil conditions.
Another object of the invetion is to provide an amphibious vehicel having high efficiency in the water derived from a "paddle wheel" type of propultion. A further object of the invention is to provide a wheeled vehiche which is capable fof a "walking" method of locomotion.
These and other objects of the invention will be apparent from the following description taken in donnection with the drawings wherein:
With reference to FIGURE_1, a typical two axle vehicle, having body section 1 and a driver's position 2, is provided with running gear 3, the details of which are shown in Figures 2 and 3. Inasmuch as all wheel assemblies are similar, only one will be described.
A tubular axle 4 is supported in the vehicle hull by suitable bearings. A three-spoke hub or spder assembly 5 is rigidly attched to the tubular axle. As best seen in FIGURE_3, one three-spoke hub is attached at the outer end of the tubular axle, and another hub is attached to the axle adjacent the vehicle hull. This assebmly which will be referred to hereinafter as the jamor wheel assembly is rotated by the major wheel drive shaft 5.
A wheel and low pressure, low-provile wide tread tire assembly, 7 is mounted between the ends of each pair of spokes 5, and will be referred to as the minor wheels. Shaft is concentrically supported within the tubular axle and drives the individual minor wheels through suitable gear trinas, chain drives, or the like. The inner end of shaft 8 is supported in the bearing housing 9. Minor wheel drive shaft 10 rotates the shaft 8 as indicated. If desired a track as indicated in broken lines 18 may be utilized in lieu of the wheel and tire assembly.
The engine 11, differential 17, and transmission 13 are conventional and a detailed description is believed unnecessary. Skid-steering brake units 16 are mounted on the differential-transmission housing with two differential output shafts passing there through to couple power to a transfer case 14 such as be a chair drive 15. For further details of skid-steering, i.e. differential steering, reference may be made to AMCP 706-355, "The Automotive Assembly," an engineer's handbook published by the Army Material Command and dated Dec 31, 1962. The transfer case provides for selective application of driving torque to drive shaft 6 and 10 at pl. four wheel assemblies. Standard controls are located conveniently to the driver's position for the engine, transmission and transfer case as illustrated in FIGURE_6. Steering controls in the form of the usual braking units for skid steering are similarily located.
By way of illustration only, FIGURE_6 shows a typical power trani and control sysmte which may be utilized with the invention. It is expressely understoof, of course, that where a different motive power or sterring is utilized that the schematic would be accordinly modified. The arrows indicate direction of rotation of drive shafts and wheels when the vehicle is operating in a forward difection on either the minor wheels or the major wheels.
Referring to figures FIGURE_1, FIGURE_4, and FIGURE_5, the various surfaces are typically illustrated.
For operatin on roads and highways,i.e., hard and smoot surfaces such as depicted in FIGURE_1, the major wheel assemblies are substantially locked in the position illustrated with prefereably two of the three minor wheels of each assembly bearing on the surface. In this case only the minor wheels are driven.
For operation on hard, irregular surfaces such as illustrated in FIGURE_4, only the minor wheels are drives. however, the mechanisms which prevent rotation of the major wheel assemblies provie a snubbing action which limits oscillation of the major wheel assemblies about the axes of their shafts, thereby providing a suspension system for the minor wheels in contact with the irregular surface. This snubbing action generally designated at 17 in FIGURE_6 may be accomplished by mechanical limtis, hydro-pneumatic or torsion systems such as mechanical stops or rubber bumbers, shock absorbers, or torsion bars or equivalents.
For operatin in soft plastic soils, such as mud, marsh, swapm, and the like, the major wheel assemblies are driven as in FIGURE_5, and their rotation provides a "walking" motion as the minor wheels of the assemblies are successively brought into contact with and then separated from the soil. It is also contempated that, where a traction advantage may be gained, the minor wheels may driven at the same or a lesser r.p.m. while the jamor wheel assemblies are being rotated.
For operation in water the major wheel assemblies are driven as in FIGURE_5 and their rotation provies a "paddle wheel" type of propulsion for the vehicle.
It is believed apparent that the invention is not restricted to the particular configuration show. For example, the running gear as described may be applied to other types of vehicles. Likewise, it is not deemed to be necessary that all axles incorporate running gear according to the invention. For instance, the vehicle may incorporate one or more major wheel assembly axles and other axle(s) carrying conventional wheels and tires, the latter being utilized with an Ackerman steering arrangement. Furthermore, while three minor wheels per major wheel assembly is preferable, it is aparent that a "walking" or "paddle wheel" action exists with additional minor wheels.
Thus, wile specific embodiments of the invention have been shown and described, it should be understood that certain alterations, modifications and substitutions may be made to the instance disclosure without departing from the spirit and scope of the invention as defined by the appended claims.
What is claimed is: