A bi-directional pump connected to a motor by a pair of supply/discharge lines; a regulator changes the bi-directional pump tilting angle; and a controller controls the regulator based on a turning signal outputted from a turning operation valve. At the turning acceleration, at which the signal increases, the controller calculates a motor flow rate passing through the motor and an instruction flow rate determined based on the turning signal. If the instruction flow rate is greater than a reference flow rate obtained by adding a predetermined value to the motor flow rate, the controller controls the regulator so the bi-directional pump tilting angle is adjusted to a tilting angle realizing the reference flow rate. If the instruction flow rate is not greater than the reference flow rate, the controller controls the regulator so the bi-directional pump tilting angle is adjusted to a tilting angle realizing the instruction flow rate.

A method for treating laundry in a laundry washing machine (1; 201; 301; 401) having: a washing tub (3) external to a rotatable perforated washing drum (4) configured to receive laundry; a water supply circuit (5) to supply water into the washing tub (3); a detergent supplier (60) to supply detergent (D) into the washing tub (3); a rinse additive supplier (70) to supply at least one rinse additive (S) into the washing tub (3); a first recirculation circuit (30) suitable for withdrawing liquid from the bottom region (3a) of the washing tub (3) and for re-admitting such a liquid into the bottom region (3a) of the washing tub (3). The method has a washing phase (120) during which the laundry is washed with introduction of water and detergent (D) into the washing tub (3) and tumbled by rotation of the washing drum (4), at least one successive draining phase (125) for draining liquid from the washing tub (3) and at least one following rinsing cycle (130a, 130b, 130n; 130′n; 230a, 230b, . . . , 230n) during which the laundry is treated with the rinse additive (S). The rinsing cycle (130n; 130′n; 230n) has the steps of: introducing (140; 140′; 240) a quantity (Qs) of rinse additive (S) into the washing tub (3); introducing (140; 140′; 240) a first quantity (Q1w) of water (W) into the washing tub (3); activating (141; 141′; 241) the first recirculation circuit (30) for withdrawing liquid from the washing tub (3) and re-admitting the liquid into the washing tub (3) in such a way that the rinse additive (S) is diluted with the first quantity (Q1w) of water (W) at the bottom region (3a) of the washing tub (3); introducing (142; 142′) the diluted rinse additive into the perforated washing drum (4) in order to be absorbed by said laundry.

A piston-slipper assembly and method for assembling a piston-slipper assembly for use in a hydraulic apparatus such as a piston motor or piston pump. The assembly contains a piston and a slipper, and at least one of the piston or the slipper includes a ball and the other includes a socket. The ball is retained in the socket without crimping, swaging or bending of the socket.

A variable displacement axial piston pump including a cylinder block defining a plurality of cylinder bores, each receiving a piston. A swash plate having a piston-supporting surface is pivotally supported relative to the cylinder block. A port block defines first and second pumping ports arranged in fluid communication with the plurality of cylinder bores such that, during operation of the pump, one of the first and second pumping ports is configured to supply fluid to the cylinder bores for pumping, and the other of the first and second pumping ports is configured to receive fluid pumped from the plurality of cylinder bores. The swash plate partially defines at least one variable volume control chamber, and the swash plate is operable to tilt with respect to the port block in response to a fluid pressure change in the at least one control chamber.

A swash plate type piston pump includes a plurality of pistons, a cylinder block including a plurality of cylinders for housing the pistons, a swash plate for reciprocating the pistons to expand and contract volume chambers of the cylinders with the rotation of the cylinder block, a biasing mechanism for biasing the swash plate in a direction to increase a tilting angle, a first control pin for driving the swash plate in a direction to reduce the tilting angle according to a first load pressure, and a second control pin for driving the swash plate in a direction to reduce the tilting angle according to a second load pressure. The first and second control pins are connected in series.

An oil-pressure driving system includes a variable displacement oil-pressure pump, tilting angle adjuster, electric motor, and control device. In the control device, a target assist torque calculating portion calculates a target assist torque, a first torque limiting portion limits the target assist torque to an output value that is a virtual limit value or less, and a drive control portion controls the electric motor such that the electric motor outputs a command torque corresponding to the output value. Further, in the control device, a torque deficiency calculating portion calculates a torque deficiency by subtracting the output value from the target assist torque, a tilting angle calculating portion calculates a tilting angle command value by which the output torque of the oil-pressure pump is reduced by the torque deficiency, and a tilting angle control portion outputs a tilt signal corresponding to the tilting angle command value to the tilting angle adjuster.

A lift apparatus and method for driving a downhole reciprocating pump is disclosed. The apparatus includes a hydraulic cylinder having a piston and a hydraulic fluid port, the piston being coupled to a rod for driving the reciprocating pump, the piston being moveable between first and second ends of the cylinder in response to a flow of hydraulic fluid through the hydraulic fluid port. The apparatus also includes a variable displacement hydraulic pump coupled to receive a substantially constant rotational drive from a prime mover for operating the hydraulic pump, the hydraulic pump having an outlet and being responsive to a displacement control signal to draw hydraulic fluid from a reservoir and to produce a controlled flow of hydraulic fluid at the outlet. The apparatus also includes a hydraulic fluid line connected to deliver hydraulic fluid from the outlet of the hydraulic pump through the hydraulic fluid port to the cylinder for causing the piston to move through an upstroke away from the first end and toward the second end of the cylinder. The apparatus further includes a valve connected between the hydraulic fluid port and the reservoir, the valve being responsive to a valve control signal for controlling discharge of hydraulic fluid from the hydraulic fluid port of the cylinder back to the reservoir to facilitate movement of the piston through a downstroke away from the second end toward the first end of the cylinder. The valve is operable to prevent flow of hydraulic fluid through the valve during the upstroke and the hydraulic pump is operable to prevent flow of hydraulic fluid back into the outlet of the hydraulic pump during the downstroke.

An electrical pressure control load sense system having a pump connected inline to an operator control spool valve and a compensation circuit. The system also has a plurality of sensors, at least one pressure transducer, a micro-processor, a fixed orifice, a proportional pressure relief valve, and a swashplate angle sensor.

A hydraulic transaxle of the present invention includes an axle, a hydraulic static transmission (“HST”), a center case that has pair of oil passages for circulating the hydraulic oil between the hydraulic pump and the hydraulic motor, and a gear mechanism that transmits an output of the HST to the axle. A case supports the axle and accommodates the HST while also forming an oil reservoir. A hydraulic motor of the HST includes a motor shaft, a cylinder block with a plurality of cylinders fixed to the motor shaft, a plurality of pistons inserted into the cylinders, a fixed swash plate abutted by the plurality of pistons, and a fixed swash plate holder that supports the fixed swash plate with respect to the case. The motor shaft of the hydraulic motor is supported by the center case and the fixed swash plate holder.

A pump displacement control device includes: a servo piston that changes a tilt angle; a flow rate control spool that is displaced corresponding to an input pressure; a power control spool that is displaced corresponding to a discharge pressure of the pump; a control pressure regulating spool that regulates a control pressure which controls the servo piston; and a feedback lever connected to the servo piston and the control pressure regulating spool. The feedback lever directly abut on either one of the flow rate control spool or the power control spool for regulating the control pressure.