Drive transmission for vehicles

Abstract

The present invention provides a drive transmission for vehicles, which is interposed in a driving power transmission line extending from a driving power source to driving wheels, which includes a main driving shaft, a hydrostatic transmission (HST), a mechanical transmission and a planetary gear device. An input shaft of the HST is adapted to receive a part of driving power of the driving power source, which is branched from the main driving shaft, and the output shaft of the HST is adapted to output the driving power variable in response to the operation of the volume varying operation member. A driving shaft of the mechanical transmission is adapted to receive a part of the driving power from the driving power source via the main driving shaft. The planetary gear device includes a sun gear non-rotatably coupled to the output shaft of the HST, a carrier non-rotatably coupled to the driven shaft, planet gears in mesh with the sun gear to be moved therearound according to the rotation of the carrier, and an outer ring with an internal gear in mesh with the planet gears, in which the driving power to be transmitted to the driving wheels is taken out of the outer ring.