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 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 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: 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: 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 braking system comprises one or more brake cylinders (100, 200, 300, 400) each associated with one or more wheels, a fluid supply (10), and a brake control (14) for commanding the feeding of fluid to the cylinder or cylinders via one or more brake valves and one or more brake pipes (44, 46). The system also comprises a function selector (50) adapted to adopt an antislip mode position (50A) or antilock mode positions in which it connects a branch pipe (52) to a fluid feed pipe (54) or to a return line (56) and a control valve (110, 210, 310, 410) for the or each brake cylinder adapted to adopt a normal braking position (100A, 210A, 310A, 410A) to connect the cylinder to the brake pipe (44, 46) and one or more special mode positions (110B, 210B, 310B, 410B) to connect the cylinder to the branch pipe (52) that the function selector connects to the return line or to the feed.

Abstract: The device comprises a replenishing valve (24) having an opening control chamber suitable for being connected to a main duct (12, 14) of the circuit, and a closing control chamber, the pressure in said chambers making it possible to cause the moving member of the replenishing valve to move so as either to connect or not to connect the main duct to which said valve is connected to a pressure-free reservoir. The device further comprises a control valve (46) which is controlled as a function of at least one control parameter representing a state of the circuit other than pressure in said main duct to which said replenishing valve (24) is connected, in order to connect the closing control chamber to the pressure-free reservoir or in order to isolate said chamber from said reservoir.

Abstract: The motor comprises a cam and a cylinder block mounted to rotate one relative to the other. The cam comprises a plurality of cam lobes and the cylinder block has a plurality of cylinders slidably receiving pistons that are suitable for co-operating with the cam. The motor further comprises a fluid distributor that includes distribution ducts suitable for being connected to a feed or to a discharge and disposed in register with the rising ramp and with the falling ramp of the cam lobes. The motor is a substantially constant-velocity motor. In any relative position of the cylinder block and of the cam, there is at least one cam lobe that is unused and with which no piston co-operates, and the angular spacings between consecutive cylinders are mutually different and differ from a multiple of the smallest angular spacing between consecutive cylinders, the angular spacings being determined so that the resultant of the forces exerted by the pistons on the cam is small or substantially zero.

Abstract: A method of operating a brake system for a hydraulic motor, by feeding the hydraulic motor with at least one pump having a variable cubic capacity, in a closed circuit, providing a friction brake to brake the motor, providing a brake controller that controls an amount of applied frictional braking by the friction brake and an amount of applied hydraulic braking, and determining a level of actuation of the brake controller to detect normal and emergency braking situations. In normal braking situations, the proportional amount of frictional and hydraulic braking is managed as a function of parameters to cause progressive hydrostatic braking to occur by causing a ratio between the fluid flow rate delivered by the pump and the active cubic capacity of the motor to decrease progressively. In emergency braking situations there is a controlled sudden decrease in the ratio between the fluid flow rate delivered by the pump and the active cubic capacity of the motor, and then progressive hydrostatic braking occurs.

Abstract: A hydrostatic transmission circuit for a vehicle having at least two displacement members (12) driven by at least one hydraulic motor (10) having a feed main duct and a discharge main duct (16, 18). Skid control means for controlling skidding of at least one displacement member comprise a skid control valve (20) and an additional valve (22) that are disposed in parallel on a main duct (16). At least the skid control valve (20) has a constriction of variable section, while the additional valve has two end positions (22A, 22B), in which its through sections are respectively at their maximum and at their minimum. Control means (UC, 26, 28) make it possible to cause said valves to move as a function of a skid situation detected by detection means (24).

Abstract: A hydraulic motor having radial pistons, and comprising a cam, a cylinder block and a distributor. The cylinders of the cylinder block are connected to communication orifices (32A) situated in a communication face of the cylinder block, while the distributor has a distribution face in which distribution orifices (21A, 23A) are provided that are suitable for communicating with the communication orifices for rotating the motor. The cam is provided with a plurality of lobes (50, 50?), each of which has two ramps (51, 52), each ramp corresponding to a distribution orifice (21A, 23A). The edge of each of at least certain communication orifices (32A) has at least one notch (54A, 54B) suitable for establishing a small section of communication with a distribution orifice. The invention applies in particular to hydraulic motors having radial pistons for which the ratio between the number of cylinders and the number of cam lobes is in the vicinity of 1.

Abstract: The circuit includes a main pump, a hydraulic motor, two main ducts, a selector for connecting the main ducts to the main pump or to a reservoir or for isolating them therefrom, a boost duct, and two pressure limiters disposed between the main ducts. A relief valve device that can take up a retention position and a relief position in which it connects one main duct (14, 16) to a relief enclosure can take up its relief position when, with the selector isolating the main ducts from the main pump and from the reservoir, the difference between the pressure in the main duct to which the control duct is connected and a relief pressure higher than the boost pressure changes sign.

Abstract: The device comprises a replenishing valve (24) having an opening control chamber suitable for being connected to a main duct (12, 14) of the circuit, and a closing control chamber, the pressure in said chambers making it possible to cause the moving member of the replenishing valve to move so as either to connect or not to connect the main duct to which said valve is connected to a pressure-free reservoir. The device further comprises a control valve (46) which is controlled as a function of at least one control parameter representing a state of the circuit other than pressure in said main duct to which said replenishing valve (24) is connected, in order to connect the closing control chamber to the pressure-free reservoir or in order to isolate said chamber from said reservoir.

Abstract: The vehicle has two groups of displacement members (1, 2, 3, 4), one of which groups is steerable. The apparatus comprises a closed transmission circuit which includes a pump (50) and hydraulic motors (10, 20, 30, 40). A first group of motors that serves to drive two displacement members on the same axle comprises at least two double motors (30, 40), each having two operating cubic capacities forming two elementary motors (31, 32; 41, 42). The first elementary motor (31, 41) of each of the double motors is connected to the pump (50) in parallel with a motor (10, 20) of the other group, while the second elementary motor (32, 42) is connected in series with said motor of the other group. There thus exist first and second series ducts (C32, C42) between the motors.

Abstract: A hydraulic motor having radial pistons, and comprising a cam, a distributor, and a cylinder block whose cylinders are connected to communication orifices situated in a communication face of the cylinder block. The distributor has a distribution face in which distribution orifices open out that are suitable for communicating with the communication orifices while the cylinder block and the distributor are turning relative to each other. The cam is provided with a plurality of lobes, each of which has two ramps (50), each of which has a convex portion (51) and a concave portion (52). The edge of each distribution orifice has a leading portion (B1) via which communication between the distribution orifice and the communication orifices opens, and a trailing portion (B2) via which said communication closes.