Improvements in or relating to tractor-trailer combined vehicles
311,887. Thornycroft & Co., Ltd., J. I., and Thornycroft, Sir J. E. March 31, 1928. Endless-track vehicles.- A combined tractor and trailer vehicle comprises a four wheel tractor A having a pair of rear driving wheels A<1> and provided with means whereby it can be coupled to the front axle f of a trailer B, the said axle being held at a fixed distance from the tractor to permit of endless tracks m being applied to the rear wheels of the tractor and the front wneels B<1> of the trailer. The endless tracks are for use on soft ground; on hard ground the tracks would be removed. The coupling means between the tractor and trailer axles may be adjustable to tension the endless tracks, or the tracks themselves may be adjustable. Part of the trailer load may be taken by the tractor. In the construction shown in Figs. 1 and 2 the tractor and trailer are coupled by radius rods n pivoted to the trailer axle at n' and provided with adjustable screw connections s to brackets r pivoted to the tractor frame. The brackets have open sides so that the rods can be readily inserted and removed, pins r<2> preventing the rods from being accidentally detached. Part of the trailer load is transferred to the tractor by means of springs d pivoted to tractor frame brackets b at c and controlled by adjustable spring plungers g, their rear ends passing through clips e underneath the trailer axle f. The additional load on the tractor axle is adjusted by means of screws k acting on the plunger springs i. In the construction shown in Fig. 6 each spring acts as a radius rod or coupling, its rear end passing through an eye e<1> in the trailer axle and being provided with a collar d<1> and a hole through which passes a cotter d<2>.