Abstract: An hydraulic transmission device (10,110) comprising an hydraulic motor (16, 18), an hydraulic pump (20), a fluid accumulator (22). The device has an accumulator-driven mode, an energy-recovery mode, a pump-driven mode. In the pump-driven mode, the pump supplies the motor with fluid drawn from an unpressurized reservoir; and in the energy-recovery mode, the motor is supplied by the pump drawing fluid from said reservoir. An assembly (1) comprising a device (10,110) as defined above, a shaft (11, 13), and a mass (12, 14) mounted eccentrically on the shaft.

Abstract: A hydraulic valve having firstly a feed port, a low-pressure link port, and a high-pressure link port, which ports are respectively connected to the feed and discharge ducts of a hydraulic motor, to a low-pressure fluid source, and to a high-pressure accumulator, and secondly an auxiliary port. The valve has a slide that can take up a neutral position for connecting together the feed, discharge, and auxiliary ports, an energy recovery position for connecting together respectively the feed and low-pressure ports, and the discharge and high pressure ports, and an energy delivery position for connecting together respectively the feed and high-pressure ports, and the discharge and low-pressure ports. The slide is caused to move from its neutral position to its other positions by control signals and the auxiliary port can be connected to a reservoir or to a clutch fluid source for clutching or declutching the motor.

Abstract: A hydraulic circuit having a brake pipe suitable for being connected to a pressurized fluid source or to a pressure-free reservoir, i.e. to a reservoir without excess pressure, via a proportional pressure reducer controlled by an electronic control unit (ECU). The circuit includes link solenoid-valve means suitable for connecting the proportional pressure reducer to the reservoir or, via a calibrated pressure reducer, to the pressurized fluid source.

Abstract: A circuit having at least one hydraulic motor, two main ducts for feeding or discharging the at least one motor, a low-pressure fluid source, and a high-pressure accumulator forming a high-pressure fluid source. The circuit is suitable for operating in an energy recovery mode in which the feed main duct is connected to the low-pressure fluid source and the discharge main duct is connected to the high-pressure accumulator, and in an energy delivery mode in which the connections are inverted. The low-pressure fluid source has a high-flow-rate booster pump suitable for delivering a flow-rate of fluid that is sufficient to feed fluid to the at least one hydraulic motor while the motor is at maximum speed in energy recovery mode, and an adjustable pressure limiter suitable for being controlled so as to cause the pressure of the fluid at the outlet of the low-pressure fluid source to vary.

Abstract: A piston including a body having a guiding and sealing surface, a base, and a top, which top is provided with a cradle-shaped recess in which a journal-bearing lining is retained by stop surfaces formed on the edges of the recess. The stop surfaces are formed by deforming the edges of the recess towards the inside thereof.

Abstract: A piston for a hydraulic motor including a body having a guiding and sealing surface, a base, and a top, which top is providing with a cradle-shaped recess. The base is provided with an additional cradle-shaped recess whose concave surface faces in the direction in which the concave surface of the recess in the top faces.

Abstract: A valve including a valve body having an inlet port and an outlet port, a valve stem, a valve seat, an opening control chamber for the valve stem, which chamber, by being fed with fluid, urges the valve stem to move towards the open position of the valve, a return spring of opposing effect, and a piston suitable for sliding in the body so as to urge contact to be established between the valve stem and the seat. The valve seat is formed on the piston, which piston is provided with a bore in which the valve stem is in its closure movement, the fluid flows out via a constriction from a damping chamber.

Abstract: A hydraulic mechanism including a cylinder block having radial pistons and mounted to rotate in a stationary casing, and a distribution cover that forms a portion of the casing that has feed and discharge ducts that extend between an outside face and inside of face of the cover. The internal distributor has distribution ducts that are selectively connected to the feed and discharge ducts that open out into a distribution face that is perpendicular to the axis of rotation and that is disposed against the communication face of the cylinder block so as to cause the distribution ducts to communicate with the cylinder ducts. In a zone defined radially outwards by end-wall portions of the cylinders, a transverse face of the cylinder block is provided with an axial setback in which at least a portion of the distributor is disposed.

Abstract: A motor having two series of distribution ducts each having two groups of ducts. The displacement selector is able to occupy a large displacement position in which the first groups of distribution ducts of the first series are connected to a main duct while the second groups are connected to the other main duct, and a small displacement configuration in which the first group of distribution ducts of the first series is connected to a main duct, the second group of distribution ducts of the first series is connected to the other main duct and a bypass connection exists between the first and the second group of distribution ducts of the second series. The device has a restriction in order, in the small displacement configuration, to restrict this bypass connection.

Abstract: A hydraulic transmission system for a vehicle, the system including: a main pump serving to feed with fluid at least one hydraulic motor for driving a vehicle mover member; an auxiliary pump, the main pump and the auxiliary pump being suitable for being actuated jointly by drive means; and a “bypass” connection between a delivery orifice of the auxiliary pump and an unpressurized reservoir. First constriction means, arranged on the bypass connection, maintain a pump protection pressure in a pump protection portion of the bypass connection; this pressure is applied to the main orifices of the main pump when said pump is actuated but is not delivering, thereby ensuring that the pump is protected.

Abstract: Hydraulic transmission apparatus including a pressurized fluid source and at least one hydraulic motor fed by said pressurized fluid source. The motor has two motor ducts for feed/discharge, and one casing duct. The motor can be operated in assisted mode, in which it generates torque or in unassisted mode in which it does not generate any torque and its pistons are maintained in the retracted position under the effect of the pressure in the casing duct. The apparatus further includes an accumulator suitable for feeding: the motor ducts during a stage of passing from the unassisted mode to the assisted mode in order to facilitate deployment of the pistons; and the casing duct during a stage of passing from the assisted mode to the unassisted mode in order to facilitate retraction of the pistons. This apparatus thus enables the motor to be positively clutched/declutched quickly.

Abstract: A hydraulic circuit including a first motor set, and a second motor set for driving vehicle-moving means situated one behind the other. The circuit has first, second, third, and fourth main ducts for feeding the motor sets in parallel. The device includes a selector suitable for taking up a first stable position making the feeding in parallel possible by interconnecting in pairs the feed and discharge main ducts, and for taking up a second stable position in which one of the motor sets is inactive because one of the main ducts is connected to one of main ducts of the other set. Between the stable positions, the selector can take up a temporary position, in which all four main ducts are interconnected. At least while the selector is moving in one direction between its two stable positions, the temporary position is sustained in an intermediate stage during which at least one of the interconnections between the main ducts of the first and second motor sets is constricted.

Abstract: A hydraulic machine (60, 70) comprising a housing (12, 14, 16) and at least first and second hydraulic units. Each unit comprising a cylinder block (36A, 36B) located in the housing and having pistons (42), and a shaft (18, 20) in rotational engagement with the cylinder block (36A, 36B). The shafts (18, 20) being arranged coaxially and being coupled so as to rotate together. The machine (60, 70) further comprising bearings (30, 32, 34, 71) for supporting the shafts (18, 20) in the housing (12, 14, 16). The shafts (18, 20) are coupled by corresponding male and female splined end portions (18A, 20A) thereof engaged one in the other, and the bearings (30, 32, 34, 71) comprise first and second bearings (30, 32) for respectively supporting the shafts (18, 20) at portions thereof located on the other sides of the cylinder blocks (36A, 36B) with respect to said splined end portions (18A, 20A).

Abstract: An open hydraulic circuit comprising a main pump (P), a hydraulic motor (M), two main ducts (10, 12) constituting a feed main duct and a discharge main duct and connected to the pump or to a reservoir (R) via a feed selector (14). The circuit further comprises a multifunction valve device comprising a multifunction selector (20) for connecting the main duct that is at the higher pressure to a pressure limiter (24) and for connecting the main duct that is at the lower pressure to booster means (16), and for interconnecting the main ducts by connecting them to the pressure limiter when the pressures in the main ducts are substantially mutually equal.

Abstract: The mechanism such as a motor or a pump comprises a cam (10) and a cylinder block (12) which has a plurality of cylinders (14A, 14B, 14) connected to communication orifices (34A, 35A; 34B, 35B) disposed in a communication face (18). The mechanism further comprises a fluid distributor (20) having a distribution face (22) which is provided with distribution orifices (31A-31F, 32A-32F) suitable for being connected to the feed or to the discharge. The communication orifices and the distribution orifices communicate with one another as the cylinder block and the distributor rotate relative to each other. At least certain cylinders (14A, 14B) are connected to at least two communication orifices (34A, 35A; 34B; 35B) spaced apart angularly (?) so that they communicate simultaneously with respective distribution orifices connected to the feed or to the discharge.

Abstract: A hydraulic valve having firstly a feed port, a discharge port, a low-pressure link port, and a high-pressure link port, which ports are respectively connected to the feed and discharge ducts of a hydraulic motor, to a low-pressure fluid source, and to a high-pressure accumulator, and secondly an auxiliary port. The valve has a slide that can take up a neutral position for connecting together the feed, discharge, and auxiliary ports, an energy recovery position for connecting together respectively the feed and low-pressure ports, and the discharge and high pressure ports, and an energy delivery position for connecting together respectively the feed and high-pressure ports, and the discharge and low-pressure ports. The slide is caused to move from its neutral position to its other positions by control signals and the auxiliary port can be connected to a reservoir or to a clutch fluid source for clutching or declutching the motor.

Abstract: A hydraulic machine having a housing, a cylinder block located in the housing and having axial pistons slidably movable in cylinders, a shaft rotationally connected to the cylinder block, and a swash plate in load engagement with the pistons of the cylinder block. The swash plate is pivotally mounted in the housing by at least one bearing, such that said swash plate is pivotally adjustable about a kinematic axis to alter a hydraulic displacement of the pistons in the cylinder block. The thrust pistons are located between the swash plate and the housing so as to urge the swash plate toward the cylinder block.

Abstract: The circuit comprises a main hydraulic pump (52), two main ducts (50, 54), a booster pump (56), a hydraulic motor (10; 20) which comprises two elementary motors (11, 12; 21, 22) for driving a first displacement member (1, 2), and a second hydraulic motor (30; 40) for driving a second displacement member (3, 4). The second elementary motor (12) is in parallel with the second main motor (30) while the first elementary motor (11) and the second main motor (20) are connected to a feed or discharge additional duct, e.g. via a series link between them. The booster pump (56) is connected to the additional duct, e.g. an interconnection duct (60; 62) for interconnecting the first elementary motor (11; 21) and the second main motor (30; 40). A replenishing valve (70) is suitable for connecting one of the main ducts to a pressure-free reservoir (51) and the circuit further comprises means (72) for preventing said replenishing link from being established on detecting a condition that reveals a spin situation.

Abstract: A hydrostatic piston machine having a cylinder block with several cylinders, in which are slidably mounted pistons in load engagement with a reaction member via transmission members, each transmission member is connected to at least one of the piston or the reaction member via a spherical joint comprising a ball recess and a ball pivot comprising a convex spherical surface. The ball pivot has an ending rotational surface which is continuously connected to the convex spherical surface, created by rotating a continuous generating line around the axis of symmetry of the ball pivot, or at least one of the ball recess or the ball pivot has an end wall which is deformable under the loads acting on the spherical joint, so as to provide for an ending rotational surface having a curvature which is different from an initial curvature thereof.

Abstract: The hydraulic machine having axial pistons comprises: a cylinder block mounted to rotate about a first axis of rotation; and a swash plate supporting a sliding disk in rotation about a second axis of rotation which is inclined relative to the first axis of rotation. Coupling rods are connected to the pistons via first spherical joints and to the sliding disk via second spherical joints. For each coupling rod, a synchronization system for providing synchronization between the cylinder block and the sliding disk has two drive surfaces stationary respectively relative to the coupling rod and relative to the sliding disk, the second drive surface being off-center relative to the second spherical joint of the rod, such that a reference amount of clearance between said second drive surface and a first drive surface is small in the zone in which said surfaces come into contact at the time of synchronization in the preferred direction of rotation.