GB261434A - Improvements in or relating to motor propelled road vehicles - Google Patents

Abstract

261,434. Dawson, Sir A. T., and Buckham, Sir G. T. May 15, 1925. Endless-track vehicles. -A motor road vehicle of the kind having endless-track and road wheels for alternative use, the conversion from one form to the other being carried out by moving the endless-tracks up and down relatively to the chassis, is provided on each side with a main track frame C<2> pivoted on the back axle, and a secondary frame C<3> pivoted at c<3> to the main frame C<2>. The two frames C<2>, C<3> are raised and lowered simultaneously by means of a hand- or power-driven transverse shaft C<6> which drives (1) a pinion C' carried by each frame C<2> and gearing with a toothed sector a<1> on the vehicle frame A, thus raising and lowering the frame C<2>, and (2) a screwed shaft C' acting on the toggle links c<9> provided between the frames C<2>, C<3>, to raise and lower the latter frame. The frame C<2> is locked in its lower position by a bolt A<2> and the toggle links are arranged to pass their dead centres and abut against a stop c<9x> to lock the frame C<3> in its lower position. The shaft C<6> is driven from the engine shaft D through a clutch d, chain gearing, and reversing gearing combined with friction clutches in a box E. The reversing gear is controlled by a hand lever E<1> which also operates the bolt A<2> locking the main track frame C<2> and clutches B<2>, Fig. 3, or other means determining whether the road wheels or the tracks are driven. The driving sprocket wheels C<1> of the tracks are mounted loosely on the driving-wheel axles and are driven either directly from the differential axle-shafts b<x> through the clutches B<2> or from the differential planet-carrier through the epicyclic gearing shown in Fig. 9. In the construction where the drive is transmitted to the tracks through the differential gear and the clutches B<2>, steering is effected by means of brakes acting on the sprocket wheels and applied one at a time by the steering hand-wheel. These brakes may also be operated independently of each other by separate hand levers d<5xx>. In the construction shown in Fig. 9, the differential casing D<3> carries internallytoothed rings d' gearing with planet pinions d' carried by sleeves D<4>x fixed to the sprocket wheels, the sun pinions D<5> of the epicyclic train being adapted to be held stationary by means of brake drums d<5>. In this construction the road wheels are always driven, and the tracks are only driven when the brakes d<5> are applied. These brakes are controlled independently by hand levers (not shown) and also are connected with the sprocket-wheel brakes to the steering handwheel so that when the latter is rotated one or other sun-wheel brake is released and the corresponding sprocket wheel is braked. An emergency hand-operated gear is provided for raising and lowering the tracks if the poweroperated gear fails.