Transmission apparatus for a vehicle having at least two drivable displacement members in line

A transmission apparatus for a vehicle, comprising first and second displacement members disposed one behind the other in the direction of displacement of the vehicle, the apparatus further including a hydraulic pump and first and second dual-capacity hydraulic motors to which the first and second displacement members are respectively coupled, each of said hydraulic motors further comprising two elementary motors, each elementary motor having first and second elementary connections for feed or discharge purposes, the first elementary connections being put in common to form a first main connection of the dual-capacity motor, while the second elementary connections are separate and form respectively second and third main connections of the dual-capacity motor, the first main connection of the first hydraulic motor being connected to a fluid feed duct coming from the pump and the first main connection of the second hydraulic motor being connected to a fluid return duct, the second main connections of the first and second hydraulic motors being interconnected via an interconnection duct;

• said apparatus further including a selector having at least two positions, and connected to said fluid feed duct, to said fluid return duct and to the third main connection of at least one of the first and second hydraulic motors, said selector having a high-torque position in which both hydraulic motors when considered together with respect to their being fed with fluid by the pump present a first total cylinder capacity, and a high-speed position in which both hydraulic motors when considered together with respect to how they are fed with fluid by the pump present a second total cylinder capacity smaller than said first total cylinder capacity.