Abstract: A four wheel drive vehicle suitable for use as a wheelchair or the like. The vehicle has a steering arrangement which allows the vehicle to be steered merely by selectively driving the left and right wheels. The steering arrangement requires at least one of the front and rear pairs of wheels to be castor mounted so as to be freely pivotal around respective pivot pins, with the pair of castor mounted wheels being linked so that they pivot generally in unison. Preferably, each of the castor mounted wheels rotate in a vertical plane which is laterally spaced from the pivot pins.

Abstract: To enable an invalid's wheelchair to negotiate stairways, it has a chassis frame equipped with ordinary motor-driven road wheels for level running and a pair of crawler belts for stair ascent or descent. Either the wheels or the belts may be selected, either to the exclusion of the other, as the mode of travel. A chair or like load carrier is movably mounted on the frame, and linkage is provided so the center of gravity of the load is adjusted to give the required stability for the selected travel mode.

Abstract: To enable an invalid's wheelchair to negotiate stairways, it has a chassis frame equipped with ordinary motor-driven road wheels for level running and a pair of crawler belts for stair ascent or descent. Either the wheels or the belts may be selected, either to the exclusion of the other, as the mode of travel. A chair or like load carrier is movably mounted on the frame, and linkage is provided so the center of gravity of the load is adjusted to give the required stability for the selected travel mode.