Driveline for a track laying vehicle

Abstract

A driveline for a track-laying vehicle having a prime mover and a pair of output shafts (L, R) connected to drive left- and right-hand tracks comprises: two similar continuously-variable-ratio transmissions (10, 20) of the toroidal race-rolling traction type, each having an input adapted to receive input drive from the prime mover and an output; a cross shaft (CS); two similar summing epicyclic gear output units (12, 22) each having a first input (70, 80) geared to the output of a respective transmission unit, an output connected to a respective output shaft (73, 83), and a second input (72, 82) connected to the cross shaft; gear drain (30) for connecting the input drive to the cross shaft at a first predetermined ratio, for low regime operation; a middle regime differential gear arrangement (40) having two inputs connectable at second and third predetermined gear ratios respectively to the corresponding first inputs of the output epicyclic gear units, and an output connectable at a fourth predetermined gear ratio to the cross shaft, operable in a middle regime; and gear drain (50) for connecting the input drive to the cross shaft at a fifth predetermined ratio, for high regime operation. This can provide a particularly compact and effective steerable continuously variable transmission.