Patent ID: 6991058

Claim:
Hydrostatic transmission apparatus for a vehicle having a group of front displacement members and a group of rear displacement members, the displacement members of one of said groups being steerable relative to the displacement member(s) of the other group, the apparatus comprising a closed transmission circuit which includes a pump and hydraulic motors of a group of front motors and of a group of rear motors driving the front and rear displacement members, a first one of the groups of motors comprising at least two motors to which two displacement members situated on either side of the vehicle are respectively coupled, the two motors of said first group of motors being double motors, each having two distinct operating cubic capacities that correspond respectively to first and second elementary motors, the first elementary motor of each of the double motors being connected to the pump in parallel with a motor of the second group of motors, while the second elementary motor is connected in series with said motor of the second group of motors, first and second series ducts thus existing between the second elementary motors of each of the double motors and the second group of motors, said series ducts being normally connected to a low-pressure circuit via means for limiting the pressure in the series ducts, and the apparatus further comprising means for limiting a flow rate of fluid flowing between the series ducts end said low-pressure circuit.