Abstract: The invention relates to a fluid mechanism supplied with pressurized fluid by means of a "dis-engageable" valve-seat. Such mechanism further comprises a controlled and independent device for re-engaging the said valve-seat. The invention finds an application in the production of a hydraulic relief engine for use on a trailer pulled by a tractor.

Abstract: The invention relates to a drive-assisting device comprising at least a fluid relief engine, a source of pressurized fluid, an engine supply pipe connecting the delivery connector of the fluid source to the inlet connector of the engine, and a calibrated discharge valve, shunt-connected to the supply pipe and provided with means for adjusting its calibration, the control of which is deliberate.

Abstract: A fluid feed device comprising a constant cylinder capacity pump and at least one variable cylinder capacity pump driven from a single prime mover, the variable cylinder capacity pump being provided with a regulator for reducing its cylinder capacity as the feed pressure increases. The regulator is such as to reduce the power absorbed by the variable cylinder capacity pumps as the pressure increases by an amount equal to the increase in the power absorbed by the constant cylinder capacity pump such that the total power absorbed by the pumps remains constant and equal to the power of the prime mover.

Abstract: This invention relates to an apparatus for feeding pressurized fluid by a constant c. c. pump and a variable c. c. pump, both driven by a single motor.A valve actuated by a centrifugal governor ensures the feed of a jack adjusting the position of the member for adjusting the cubic capacity of the variable c. c. pump.One application is the drive of pumps of which the sum of the maximum powers is greater than the maximum power of the motor.