Abstract: A hydrostatic power transfer system for transferring power from a rotating power input shaft to a rotating output shaft comprises a fluid pump driven by the power input shaft. A pump outlet supplies pressurized fluid to a pressure accumulator disposed downstream of the pump. The accumulator has an outlet for discharging fluid under pressure from the accumulator to at least one fluid motor. The accumulator includes two chambers and a pressure transmissive member separating the two chambers. The pressurized fluid from the pump is supplied to and discharged from one of the two chambers and the other chamber includes a spring cushion such as a pressurized gas acting against the pressure transmissive member for insulating the system against vibration transmission through the accumulator.

Abstract: A method and apparatus for controlling the differential hydraulic fluid pressure (.DELTA.P) across a variable displacement hydraulic motor (10) wherein the displacement of the motor is adjusted as a function of the differential fluid pressure across the motor to maintain a near constant differential pressure across the motor when the motor is operating under an opposing load and in an intermediate region of its speed-load torque profile (FIG. 4). In order to minimize the flow requirements of the motor, the displacement of the motor is reduced to minimum when the motor is operating under an aiding load or no load. The method and apparatus are useful in an apparatus for mechanically actuating a device (22) with the variable displacement hydraulic motor (10) driven by hydraulic fluid from a hydraulic power supply (25) such as an aircraft power supply for operating components of the aircraft, e.g. rudder, wing, etc.

Abstract: Pilot control circuits are useful, for example, for controlling the actuation of main control valves of load sensing hydraulic systems. Using the main supply pump as the source of pressurized pilot fluid sometimes results in inadequate pilot pressure for maintaining the main control valves in an actuated position under some operating conditions. The subject pilot control system includes an accumulator to store pressurized fluid received from the main supply pump for use by the pilot control circuit when the pressure level of the main hydraulic system momentarily drops below a level for proper pilot control operation. Thus, the main control valves are maintained in their actuated position irregardless of the pressure level of the fluid in the main supply system.

Abstract: In a hydraulic servo unit comprising a cylinder and a piston slidably inserted therein, the cylinder chamber being divided by a piston portion into a rod-side cylinder chamber and a head-side cylinder chamber, a control apparatus for the hydraulic servo unit includes but is not limited to a first hydraulic line connecting the rod-side cylinder chamber with the hydraulic pressure source which supplies working fluid of a predetermined pressure, a second hydraulic line connecting the head-side cylinder chamber with the first hydraulic line through a first solenoid valve of duty-ratio-control, and a drain hydraulic line connecting the head-side cylinder chamber with drain through a second solenoid valve of duty-ratio-control.

Abstract: A piston structure for an internal combustion engine is provided. This piston includes an oval slipper skirt with a cross sectional profile in the form of an ellipse defined by preselected major and minor axes. A difference between the major and minor axes is gradually increased nearing a lower edge of the skirt. The skirt distorts from an elliptical shape to a round shape when side thrust acts on thrust surfaces of the skirt to provide uniform contact with a cylinder wall.

Abstract: A linear drive comprises a hydraulic unit (1), a control valve (5) and an actuating drive (9) with an actuating member (7). These elements are interconnected by means of two inertia drive starters (4, 8), which results in a mechanically-induced return movement. The movement of the piston rod (15) of the hydraulic unit (1) is controlled in the actuating drive (9) by means of active elements (10, 35, 56) moved translationally in the direction of the longitudinal axis of the linear drive. The active elements (10, 35) and the actuating member (7) are connected without play in the axial direction but can counterrotate with respect to each other by means of a bearing (38). A lever (13) is arranged on the actuating member (7) and can be rotated together with the actuating member (7) about the axis (60). The lever (13) cooperates with a stop element (14) which can be adjusted by a rack (50) and which limits the rotation of the lever (13).

Abstract: A hydraulic system for a construction machine comprising plural hydraulic actuators (23-28) driven by fluid supplied from a pump (22), first and second flow control valves (29-34) for controlling flows of fluid supplied to the first and second actuators, and first and second distribution compensating valves (35-40) for controlling first differential pressure (.DELTA.P v1-.DELTA.P v6) produced between inlets and outlets of the first and second flow control valves. The first and second distribution compensating valves have respective drives (45-50, 35c-40c) for applying control forces (Fc1-Fc2) in accordance with the second differential pressure to the associated distribution compensating valves, to thereby set target values of the first differential pressures. The hydraulic system includes first means (59) for detecting the second differential pressure (.DELTA.

Abstract: The invention relates to a brake servomotor assembly (1) consisting of a front half-shell (6) and a rear half-shell (8) and mounted on a stationary part (4, 40) of a vehicle by means of lugs (54, 56, 154) arranged in a plane perpendicular to the axis of the servomotor and around this axis, extending radially outwards and cooperating with bearing surfaces (34, 36, 134) with corresponding shapes and dimensions for mounting by mechanism of axial engagement followed by rotation, an elastic means (25, 125) being arranged between the servomotor (1) and the stationary part (4,40), the servomotor (1) having a central hub (24) on the rear half-shell (8) comprising a control valve mechanism (26) of the servomotor (1). The lugs (154) or the bearing surfaces (34, 36) are formed as a single piece with the central hub (24) and cooperate respectively with the bearing surfaces (134) or the lugs (54, 56) formed on the stationary part (4, 40) of the vehicle.

Abstract: When a first rotating shaft is rotationally driven, it rotates a first cylinder barrel splined thereto, and a second cylinder barrel and a valve block united with the first cylinder barrel. In accordance with these rotations, first pistons in first cylinders slide circumferentially on the inclined face of a first swash plate so that they are reciprocated axially in the first cylinder barrel, and second pistons in second cylinders slide circumferentially on the inclined face of a second swash plate so that they are reciprocated axially in the second cylinder barrel. Simultaneously with these reciprocations, a first change-over valve is switched in accordance with the rotations of the first rotating shaft, and a second change-over valve is switched in accordance with the relative rotations of the first rotating shaft and the second rotating shaft.

Abstract: A multiplexed hydraulic control system having a plurality of channels and a common source of modulated hydraulic fluid. The common source is shared among the plurality of channels by providing a plurality of selector valves, one for each channel, with electrical solenoids for the selector valves being individually controlled by a control means. In a normal operating mode, the selector valves are operated individually and the modulating means is controlled to direct fluid to the selected channel in accordance with the demands placed on movement of the actuator in that channel. In a second slewing mode, multiple selector valves are energized at the same time and the modulator is controlled to produce sufficient fluid flow to slew all of the actuators in the selected channels at a desired rate.

Abstract: In a two-piece piston with a head piece and a trunk hinged only over the piston pin, the annular space radially located inside the piston ring groove and open in the direction of the trunk is covered with a sheet metal wall part forming a cooling duct. The sheet metal wall part is held by a collar that extends from the outer annular wall of the head piece and is cramped around the sheet metal wall part. For optimally covering the annular space, the sheet metal wall part is radially divided into two parts.

Abstract: A tandem master brake cylinder has first and second pistons, each piston associated with a fluid chamber and a pressure chamber. The pistons are displaced in response to actuation of a brake pedal. A hydraulic booster is coupled to a power source and is operable to enhance the piston movement and for conducting pressurized fluid to a second of the fluid chambers associated with a second piston to displace that piston in a manner reducing the volume of the pressure chamber associated with the first piston. In the event that a negative pressure is communicated with the second fluid chamber, e.g. by a loss of pressurized fluid from the power source, brake fluid is supplied through a one-way check valve to the second fluid chamber to prevent the negative pressure from reversing the motion of the second piston.

Abstract: A pneumatic actuator includes a tubular body made of a rubber-like elastic material and a braided structure made of organic or inorganic high-tensile-strength fibers reinforcing an outside of the tubular body. Closure members sealingly close ends of the tubular body; at least one of the closure members has a fluid connecting passage. The tubular body deforms to expand its diameter when pressurized fluid is introduced through the connecting passage to cause contractive force in the longitudinal direction. Contraction-detecting strain gauges at one closure member provide signals corresponding to the contractive force of the actuator.

Abstract: A rigid partition (18) internally delimiting a front space and a rear space in the outer casing (10) of a brake servo unit is fastened on an approximately cylindrical extension (14a) of a reinforcing plate (14) internally lining the front portion of the casing. A two-stage servo unit of simplified construction and of small dimensions, utilizable in the brake circuit of motor vehicles, is thus obtained.

Abstract: A piston installed into a cylinder of an engine includes annular projections formed in axially spaced relation on a top land facing a cylinder inner wall and having a saw-toothed cross-section in which the external diameter of the projections are such that, when cold, that adjacent the lower end of the top land is greater than that adjacent the upper end thereof. Thereby the effective clearance between the top land face and the cylinder inner wall is reduced. This causes a reduction in the hydrocarbon content of the incompletely consumed combustion gas, and prevents the temperature from rising in the top ring groove and thus prevents the wearing of the groove.

Abstract: A tandem master cylinder for hydraulic brake systems for automotive vehicles, with the brake systems comprising a brake pressure control means, in particular, an anti-locking control means. The tandem master cylinder has a push rod piston (7) and a floating piston (8), with each piston having a central valve. The valve closure member (13) of the central valve in the push rod piston (7) can be controlled both by a pin (16) directly or indirectly abutting the housing of the tandem master cylinder and by a pin (17) coupled to the floating piston.

Abstract: A single rod three chamber fluid motor is driven in a forward stroke which includes a rapid initial advance followed by a relatively short and slow feed stroke under high pressure. The rapid advance is performed by a closed loop system in which a high displacement main pump, pumps fluid to act against a first equal area at the head side of the piston and receives fluid expelled from a second equal area at the rod side of the piston while an accumulator maintains the third chamber exposed to a third area of the head side of the piston filled with fluid. Upon shifting to the feed stroke, the main pump is disconnected and a feed pump applies pressure to both of the first and third areas at the head side of the piston and receives fluid expelled by the second equal area and from a charge pump. The access fluid added to the feed pump circuit by the charge pump is returned via the accumulator to the charge pump sump during the return stroke of the piston.

Abstract: A variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit. A pressure oil supply means includes the variable displacement hydraulic pump and a tilting controlling means for controlling a tilt angle of the hydraulic pump and supplies an amount of pressure oil corresponding to the tilt angle of the hydraulic pump to the hydraulic motor. When rotation of a prime mover is detected by a rotation detecting means, an opening and closing valve is changed over to a first position in which the pressure oil supply means is permitted to supply pressure oil. When stopping of the prime mover is detected by the rotation detecting means, the opening and closing valve is changed to a second position in which the pressure oil supply means is inhibited from supplying pressure oil.

Abstract: A hydraulic drive controlling apparatus for a construction machine has at least one variable displacement type hydraulic pump, a plurality of actuators driven with a hydraulic fluid from the hydraulic pump, directional control valves driven in accordance with amounts of manipulation of operation means for controlling the plurality of actuators, means for detecting a delivery pressure of the hydraulic pump, means for selecting maximum one of load pressures of the plurality of actuators, and first control means for controlling displacement of the hydraulic pump to bring a differential pressure between the delivery pressure and the maximum load pressure to a specified value.

Abstract: A multiplexed hydraulic control system in which high force margins for the multiplexer are achieved by employing hydraulic oscillators as the multiplexer driving means. The multiplexer is typically in the form of a hydraulic cylinder having an input port and a plurality of output ports, with an operator in the cylinder for individually connecting the input port to the output ports. The hydraulic oscillator is mechanically coupled to the multiplexer operator, and oscillation of the former causes oscillation of the latter to sequentially connect the input to each of the outputs. Various means are taught for initiating reversal of the oscillator and controlling the oscillation speed.