Motor vehicles – Special driving device – Portable track
Patent
1987-08-07
1989-05-02
Marmor, Charles A.
Motor vehicles
Special driving device
Portable track
305 16, 305 24, 305 35EB, B62D 55104
Patent
active
048259691
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a tracked vehicle suitable for unmanned deployment in hostile environments.
BACKGROUND ART
The mobility of an unmanned vehicle is extremely dependent upon the terrain, obstacles in the path of the vehicle causing various mobility failures such as overturning, gross slippage, nose-in failure and hang-up failure, the latter two being caused by engagement of the nose and belly respectively of the vehicle with the terrain.
Wide track manned vehicles having tracks extending substantially the full width of the vehicle are known for use on relatively even terrain. The tracks of such vehicles fully cover the belly and hence would be suitable for eliminating the possibility of hang-up failure were it not for the steerage problems engendered in use on uneven terrain by the mode of steering that has to be employed, ie skid steering.
Skid steering comprises the application of a velocity differential to the two independently drivable, parallel tracks of the vehicle, which application causes the tracks to skid about a pivot axis trajectory, the location of which is determined both by the velocity differential applied and by the load distribution of the vehicle upon the tracks. When the tracks are wide and the terrain is uneven it becomes difficult to predict where ground contact will take place, with consequent unpredictability of loads and rates of turn during steering.
The present invention seeks to provide a wide track vehicle with improved skid steering on uneven terrain.
THE INVENTION
Accordingly, the present invention comprises a tracked vehicle having a chassis supported on two independently drivable, parallel tracks, together extending substantially the full width of the chassis so as to cover substantially the whole belly thereof, wherein the chassis is supported upon a plurality of side support wheels, engageable with an inner face of each track adjacent the outer edge thereof, at least one longitudinally disposed rubbing strip being located inwardly of each plurality of support wheels and having less downward projection than the support wheels, thereby to be slideably engageable with the inner face of the track only when the underlying track is upwardly deflected by uneven terrain.
Preferably a parallel plurality of the said rubbing strips is provided inwardly of each plurality of side support wheels, each strip being of progressively reducing downward projection with increasing proximity to the centre line of the vehicle.
In order to maintain the geometry of the track, full width, direction changing rollers are provided at each turning point of each track, ie, where the tracks change direction. Each of these full width rollers has a rolling surface which is preferably provided with axially inclined ridges or blades in order to avoid build up of mud or clay deposits between the rollers due to low contact pressure.
The maximum height of obstacle that can be mounted by the vehicle is of course dependent upon the length of the ground engageable portion of the tracks, ie, track-base, defined by the spacing of the lower, full width, direction changing rollers, ie the road rollers. A preferred arrangement for unmanned use is provided with three only direction changing rollers comprising two road rollers and one drive sprocket roller. This arrangement is advantageous over conventional four-roller arrangements of manned tracked vehicles, both in providing a longer track base and in shifting the centre of gravity of the vehicle forward, thereby providing a vehicle which will behave well in either a forwards or a backwards direction.
Where the vehicle is intended for unmanned use, the chassis and drive mechanisms mounted thereon are contained entirely within the perimeter of the tracks. Access to the drive mechanisms may be achieved by a drawer system, ie the various components being slideably mounted on runners transverse to the longitudinal centre line of the vehicle. The chassis may also be enclosed within a body and provided with a top hamper bridgin
REFERENCES:
patent: 1964637 (1934-06-01), Hurxthal
patent: 3236568 (1966-02-01), Bombardier et al.
patent: 3418961 (1968-12-01), Gregg
patent: 3837714 (1974-09-01), Russ, Sr.
patent: 4042282 (1977-08-01), Haslett et al.
patent: 4198103 (1980-04-01), Ward et al.
Gibson Peter J.
King David W.
Hill Mitchell J.
Hinds William R.
Marmor Charles A.
The Secretary of State for Defence in Her Majesty's Government o
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