Poclain Hydraulics Industrie

Daniel Ruzicka

Louis B Bigo

Bernard R Allart

Jean-Philippe Raisin

Alain Mangano

Hydraulic motor drive apparatus having a cubic capacity selector () which has at least two positions, control means for controlling the selector, which means comprise a hydraulic control chamber () suitable for being fed with fluid via a control duct (), and first opposing return means (). The apparatus further comprises a brake system having a brake release chamber () and second opposing return means (). The control duct () is suitable for being connected to the brake release chamber (), and the first return means () are suitable for returning the cubic capacity selector to its large cubic capacity first position when the pressure in said chamber becomes lower than a first threshold pressure, whereas the second return means () return the brake means () to their braking position when the pressure in the brake release chamber becomes lower than a second threshold pressure, which is itself lower than said first threshold pressure.

Hydraulic motor device with displacement selector and a braking system

A hydraulic circuit for the hydrostatic transmission of a vehicle, said hydraulic circuit comprising at least one hydraulic motor, two main ducts, a parking brake having brake means, brake release control means suitable for feeding the brake release chamber from a first brake release fluid source, and means for connecting said chamber to a unpressurized reservoir. The circuit has a single short-circuit and selection valve having two main ports connected to respective ones of the two main ducts, and two selection ports connected respectively to the brake release chamber and to the brake release duct, and control means for controlling said valve, which control means are suitable for causing the valve to take up a first configuration in which the main ports are mutually isolated while the selection ports are interconnected, and for causing it to take up a second configuration in which the main ports are interconnected while the selection ports are mutually isolated.

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Nogent-sur-Oise, France

Daniel Ruzicka