Patent ID: 6354392
Filing Date: 2002-03-12
Classification: B60K,F16H

Abstract:
Hydrostatic transmission apparatus for a vehicle having a front group of displacement members, and a rear group of displacements members, the displacement member(s) of one of said groups being steerable members, the apparatus comprising a transmission circuit which includes a pump, and hydraulic motors in a front group of motors and in a rear group of motors, for the displacement members in the front and rear groups, a first one of the front and rear groups of motors comprising at least two motors to which two displacement members situated on either side of the vehicle are respectively coupled, while the second group of motors comprises at least one motor to which at least one displacement member is coupled, the two motors of the first group of motors being dual-capacity motors each having two distinct operating cylinder capacities which correspond respectively to a first elementary motor and to a second elementary motor, the first elementary motor of each of the dual-capacity 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, first and second series pipes thus existing between the second elementary motors of each of the two dual-capacity motors and the second group of motors;said apparatus further comprising a selection valve connected to the first series pipe via a first connection, to the second series pipe via a second connection, and to a port of the pump via a third connection, wherein said valve is suitable for taking up a straight-ahead configuration in which all three of the above-mentioned connections are isolated from one another, a left-turn configuration in which the first and third connections are interconnected via a first left branch path, while the second and third connections are interconnected via a second left branch path, and a right-turn configuration in which the first and third connections are interconnected via a first right branch path, while the second and third connections are interconnected via a second right branch path, and wherein the flow sections of at least some of said right and left branches are different.