Abstract: The present invention relates to a tandem rotary master-cylinder for a vehicle brake circuit comprising a body (10;102) in which a first vane (20;114) is mounted for rotation in response to rotation of an input shaft (12;100) in order to generate pressure in a first working chamber (18;126) formed in the body (10;102) and delimited in part by the first vane (20;114).According to the invention the master-cylinder further comprises a second vane (30;120) rotatably mounted in the body (10;102) and delimiting with the first vane (20;114) the first working chamber (18;126) the second vane being rotatable in response to rotation of the first vane (20;114) to generate pressure in a second working chamber (62;128).A rotary master-cylinder with braking assistance is also described.

Abstract: A time multiplexed hydraulic control system in which a multiple section dog valve is multiplexed among a plurality of channels. An electrical actuator on the dog valve controls pilot means. The pilot means is associated with a plurality of followers, one for each channel, and each follower controls the flow rate through an associated output port. Multiplexing means in the dog valve sequentially supplies fluid to the pilot means for sequentially positioning then locking the respective followers. Thus, each channel has continuous hydraulic flow based on the position of its dedicated follower, with the followers being repositioned on a multiplexed basis in associated time slots.

Abstract: A piston-ring arrangement for use in an internal combustion engine including a cylinder with a piston axially displaceable within the cylinder and at least one piston ring guided in the cylinder. The cylinder, piston and piston-ring are made of a ceramic material. The piston ring is formed of two circumferentially extending parts and is mounted in a groove in the circumferentially surface of the piston. The groove has a depth greater than the corresponding radial depth of the piston ring so that a spring element can be positioned between the base of the groove and the piston ring for biasing the piston ring radially outwardly. The spring element can be annular member with a corrugated shape or a multi-part ceramic member shaped to provide a biasing action.

Abstract: A fluid-operated actuator (2) is connected to a pumping unit (12) through a control unit (10) in which are mounted control valves (30,32) for regulating the movements of the actuator. The control valves communicate with the actuator and the pumping unit through conduits in replaceable adaptor plates (60a,60b,60c). By changing the adaptor plates, different operating modes of the actuator can be selected. The pumping unit is carried on the control unit through a rotationally adjustable connection to permit it to be mounted upright although the orientation of the actuator and control unit may vary.

Abstract: A hydraulic circuit for a backhoe comprising a first multiple valve, a second multiple valve, and a confluence mechanism mounted between the first and second multiple valves. The first multiple valve includes control valves connected to a first pump in parallel to one another for driving working implements. The second multiple valve includes further control valves connected to a second pump in parallel to one another for driving other working implements. The confluence mechanism is connected to a rear end of a center bypass line of the first multiple valve and to a rear end of a center bypass line of the second multiple valve. Further, the confluence mechanism, in neutral position, is connected to a return oil line for confluently returning oil from the first and second multiple valves to a tank.

Abstract: A hydraulic lifting arrangement for a lift assembly on a materials-handling vehicle includes a working piston-cylinder device (17) for raising and lowering the lift assembly, a reversible pump assembly (40) for operating the piston-cylinder device, and an electric motor for driving the pump assembly. The piston-cylinder device (17) is a double-acting device and has two working chambers (28,29), which are connected to the pump assembly by connecting pipes (46,47). The pump assembly comprises a first and a second hydraulic pump (41,42) having fixed displacements. The pumps are so arranged in the system that together they supply hydraulic medium to and receive hydraulic medium from solely the first chamber (28) whereas only the pump motor (41) supplies and receives hydraulic medium to and from the second chamber (29).

Abstract: A method of controlling a speed reduction ratio includes setting a reference engine speed in correspondence with an accelerator opening, measuring the atmospheric pressure, correcting the reference engine speed in correspondence with a change of the atmospheric pressure to compensate for a change in engine output power caused by the change of the atmospheric pressure, and controlling the speed reduction ratio so that the engine speed coincides with the corrected reference engine speed.

Abstract: A hydraulic actuating unit for raising a hospital bed includes a reservoir, a hydraulic piston cylinder device the cylinder of which has its ends connected to the reservoir through a supply conduit that contains a hydraulic plunger pump with suction and pressure valve means and through a return conduit which contains an orifice in a normally closed relief valve. A branch conduit leads to a hydraulic liquid accumulator from the supply conduit at a location between the cylinder and pressure valve means. A multiple pilot operated check valve of the differential type is provided in the branch conduit towards the accumulator. The largest and smallest end faces of the differential spool member are subject to the pressure in the branch conduit while the differential area of the spool member is subject to the pressure in a conduit which leads from the return conduit at a location between the orifice and the relief valve.

Abstract: A continuously variable speed transmission in which a bypass line is formed between two hydraulic lines disposed between a hydraulic pump and a hydraulic motor to constitute a hydraulic closed circuit, and a opening control valve is disposed to open or close the bypass line. The opening control valve is opened when the reduction rate of the engine speed or the vehicle speed exceeds a given in order to short-cut the two lines and create a neutral condition.

Abstract: A closed loop function selector valve which directs high pressure hydraulic fluid to any one of several hydraulic related devices wherein the low pressure drains or returns of all of the devices are directed back to the valve. The valve comprises a hollow valve body having a cylindrical or arcuate inside surface wherein function selector ports are located. A valve drain output port is also located within the valve body. A selector rotor is moveably seated within the valve body having a line pressurized chamber therein which is in flow communication with the pressurized hydraulic line pressure directed into the valve. A chamber exit port is located in the body portion of the selector rotor arranged to be sealably alignable with one of the function selector ports for directing the hydraulic line pressure to any one of the various hydraulic devices connected to a functional selector port. The valve drain output port is always in flow communication with the remaining function selector ports.

Abstract: A hydraulic differential cylinder comprises a cylinder, a piston slidably fitted in a cylinder chamber, a piston rod with one end coupled to said piston and an inner valve disposed in said piston rod. The cylinder chamber is divided by the piston into a rod-side cylinder chamber and a head-side cylinder chamber. The piston-pressure-bearing area of the head-side cylinder chamber is greater than the piston-pressure-bearing area of the rod-side cylinder chamber. The rod-side cylinder chamber is connected via the inner valve to a constant hydraulic pressure source. The head-side cylinder chamber is connected to a control hydraulic pressure source.

Abstract: The speed reduction ratio of a continuously variable speed transmission for transmitting engine power with continuously variable speed to drive road wheels is controlled by detecting a parameter representing a driver's intention of acceleration or deceleration, establishing a reference engine speed corresponding to the detected parameter, and controlling the speed reduction ratio so as to equalize an actual engine speed with the reference engine speed, at a predetermined time interval. When the actual engine speed is lower than the reference engine speed, a controlling ouput value for the speed reduction ratio for bringing the actual engine speed into agreement with the reference engine speed is established based on the difference between the actual engine speed and the reference engine speed, and a predicted engine speed after elapse of the predetermined time interval is calculated based on the rate of =change of the actual engine speed.

Abstract: A power-assist device for an automotive steering system employs spool valves with different external diameters to control the fluid pressure in smaller and larger area chambers of a pressure control valve which controls pressure in an unbalanced cylinder device. The different size of spool valves are disposed within different sizes of bores formed through a housing of the pressure control valve for defining wider fluid path area for introducing larger amount of working fluid into the smaller area chamber in comparison with that for the larger area chamber and narrower fluid path for draining the working fluid in the smaller area chamber for lower drainage rate in comparison with that for the larger area chamber.

Abstract: A closed-loop hydrostatic transmission is disclosed of the type with a fluid pump (10) and a fluid motor (12), both of which are variable displacement. A pair of stroking cylinders (36,38) varies the displacement of the motor between minimum displacement and maximum displacement, under the control of a motor stroking valve (70) which includes a stroking valve member (90) movable in response to changes in fluid pressure in a pressure chamber (110). The displacement of the pump is controlled by a main controller (50) in response to movement of an input handle (60). Whenever the handle (60) is moved to the neutral position, a neutral switch (122) is closed, thus generating a neutral signal which is transmitted to an electromagnetic valve member (114), which controls the pressure in the fluid pressure chamber (110) to command the motor to maximum displacement.

Abstract: To inhibit potentially damaging cold startup of a hydrostatic unit in a vehicle transmission, a portion of the makeup fluid pump to the hydraulic pump and motor loop circuit of the hydrostatic unit is directed through a branch line including a viscosity insensitive, flow regulating fluidic element and a viscosity sensitive fluidic element. The latter element develops a fluidic signal varying as a function of fluid viscosity, which is utilized to control a valve to prevent over-pressurization of the loop circuit and to control a transmission controller to condition the transmission to neutral until the hydraulic fluid warms to a safe operating viscosity.

Abstract: A duty ratio for operating a solenoid is determined by calculating a duty ratio in each of basic periods and determining an operational time for which the solenoid is to be operated within each of the basic periods, based on the calculated duty ratio. When the duty ratio is reduced to the extent that the operational time is shorter than a minimum possible time of operation of the solenoid, an operational time for which the solenoid is to be operated is determined within a new period composed of a plurality of consecutive basic periods.

Abstract: A hydraulic transmission device comprises a rotatable casing secured at one end by a first flange to an input shaft and at the other end to a second flange which supports an output shaft. Drive is transmitted by fluid introduced into an area between the outwardly directed contoured teeth extending around the periphery of a rotor, eccentrically mounted on said first flange for rotation therewith, and the inwardly directed contoured teeth extending around the periphery of an annular ring secured to said output shaft, the diameter of the rotor being smaller than the internal diameter of the annular ring thereby allowing the respective teeth of the rotor and the ring to mesh during rotation of the input shaft.

Abstract: A hydraulic system having multiple actuators is provided with positive pressure flow equalization for both advancing and retracting movements of the system by means of first and second flow divider elements for each actuator. The flow divider elements are cross-coupled between the actuators, a controllable source of pressurized fluid and a reservoir. The flow divider elements are positive-displacement gear or vane pump units that are connected by a common shaft for coordinating fluid flow to the various actuators. Two or more of the actuators can be connected for lifting a load such as an automobile, the system being provided with safety latches at each actuator, the flow dividers not only coordinating the actuator movements during normal raising and lowering operation, but also preventing loss of synchronization of the actuators in case of engagement of a subset only of the latches.

Abstract: The apparatus for the feed and control of the speed and torque of a hydraulic motor having variable swept volume according to this invention comprises a hydraulic feed device for the motor, adapted for supplying the required flow rate of hydraulic fluid under all conditions at the working pressure, a constant pressure hydraulic control circuit associated with the hydraulic device or devices for varying the swept volume fo the motor, adapted for modifying the swept volume itself in relation to the pressure of the hydraulic fluid supplied to the motor, and a flow regulator valve with proportional control, piloted by an electronic regulator generating a control signal for the valve and receiving the signal of a sensor of the rotational speed of the motor and a reference signal.

Abstract: A valve with four passages controls a piston (15) disposed in a cylinder (16). Between the body (1) of the valve and the cylinder (16) is disposed a plate (23) having passages (24, 25) which are used and a passage (26) which is not used in FIG. 1. By turning plate (23) 180.degree., the passage (24) is located in the non-use position, while the passage (26) connects the conduits (19 and 13) in such a way as to cause the space (21) of the cylinder (16) to communicate continuously with an exhaust orifice (6).