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.

Abstract: Hydraulic motor drive apparatus having a cubic capacity selector (16) which has at least two positions, control means for controlling the selector, which means comprise a hydraulic control chamber (18) suitable for being fed with fluid via a control duct (20), and first opposing return means (17). The apparatus further comprises a brake system having a brake release chamber (38) and second opposing return means (39). The control duct (20) is suitable for being connected to the brake release chamber (38), and the first return means (17) 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 (39) return the brake means (36) 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.

Abstract: A replenishing device for a closed circuit comprising at least one hydraulic motor and at least two main pipes which are connected to the pump to provide respectively the feed and the discharge for the motor. The device comprises a replenishing selector suitable for putting the main pipe that is at the lower pressure in communication with a valve which itself communicates with an atmospheric pressure reservoir. The replenishing selector and the valve are united in the same replenishing valve unit having an inlet suitable for being connected to the main pipe that is at the lower pressure, and an outlet which communicates continuously with the atmospheric pressure reservoir. The valve is suitable for causing the inlet to communicate with the outlet when the pressure in said main pipe reaches a given pressure threshold.

Abstract: The tapping circuit forms part of a main fluid circuit which comprises a hydraulic motor having a preferred operating direction and at least two main pipes suitable for communicating with the cylinder block of the motor and constituting respectively, in said preferred operating direction, a feed main pipe and a discharge main pipe. The tapping circuit comprises a single tapping and removal valve connected continuously via a tapping pipe to that one of said main pipes which, in the preferred direction, serves for discharge purposes. This valve serves to replenish the fluid so as to cool it and/or to flush the internal space of the casing of the motor.

Abstract: 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.

Abstract: A braking system for braking a rotor relative to a stator, the braking system comprising braking means respectively secured to the rotor and to the stator, a brake piston, return means for returning the piston to its braking position, a braking chamber, and a brake release chamber, which chambers are interconnected via a link duct serving to generate a flow of fluid in an assisted braking situation in which the braking chamber is connected to a fluid feed duct, while the brake release chamber is connected to a fluid return duct. The link duct is equipped with means for limiting the flow of the fluid at least in the direction going from the brake release chamber to the braking chamber.

Abstract: A valve device (10) for at least one hydraulic motor suitable for driving a mass of large inertia. The device includes first and second ducts (12, 14) serving to be connected to respective ones of the two main ducts (feed or discharge) of the motor, and an auxiliary duct (15) connected, for example, to a booster duct. The device can have two configurations, depending on which of the main ducts has the higher pressure, in which configurations the main duct at high pressure is isolated, while the main duct at low pressure is connected to the auxiliary duct. The device includes time delay means (36, 46, 38, 48) suitable for limiting the speed of transition between one and the other of the first and second configurations when the difference between the pressures in the first and second main ducts (12, 14) changes sign.

Abstract: A drive device incorporating a hydraulic motor and a planetary reduction gear. The motor includes a housing in which radial pistons are disposed. The device includes a coupling between the output of the motor and the input of the reduction gear, the reduction gear including a housing in which a planetary reduction gear system is disposed having an output provided for driving in rotation. The housing of the motor and the housing of the reduction gear form distinct enclosures and the device allows circulation of fluid between these housings and for controlling this circulation by limiting this circulation in at least one direction of circulation between the housing of the motor and the housing of the reduction gear.

Abstract: A braking system (S) for braking a rotor (5, 9, 106) relative to a stator (1C, 1′C), said system comprising two series of brake disks (102, 104) secured respectively to the stator and to the rotor and disposed in a disk enclosure (100). The system further comprises a brake piston device (108, 114, 116) urged continuously in the braking direction by resilient return means (118). The piston device is urged in the brake release direction by feeding a brake release chamber (120) with fluid, and it is urged in the braking direction by feeding a braking chamber (124) with fluid. The braking system includes a cooling device for cooling the brake disks (102, 104) by means of fluid flow, which device is provided with a cooling duct (140) branching from the brake release duct (122) which feeds the brake release chamber (120) and communicating with the disk enclosure (100). It is provided with means (148) for limiting the quantity of cooling fluid tapped by the cooling duct (140) from the brake release duct (122).

Abstract: The apparatus comprises two hydraulic motors to which two displacement members in line are respectively coupled. Each of the motors has three main connections, namely one main connection that is common to both of its cylinder capacities, and two main connections, one for each of its two cylinder capacities. The first main connection of the first motor is connected to the fluid feed and the first main connection of the second motor is connected to the fluid return. The two main connections of the motors are interconnected. A selector having at least two positions is connected to the fluid feed, to the fluid return, and to the third main connection of at least one of the motors. For each of the two selector positions, the total cylinder capacity fed by the pump differs.