A work machine includes first and second hydraulic motors, first and second hydraulic pumps provided to supply hydraulic oil in correspondence with the first and second hydraulic motors, respectively, first and second swash plate angle sensors provided in correspondence with swash plates which regulate amounts of delivery by the first and second hydraulic pumps, respectively, the first and second swash plate angle sensors each detecting an angle of the swash plate, a delivery amount setting unit which sets an ideal amount of delivery by the first and second hydraulic pumps, and a command value control unit which corrects a command value for adjusting an angle of the swash plate such that the amount of delivery in accordance with a result of detection by the first and second swash plate angle sensors is set to the ideal amount of delivery.

A work machine includes first and second hydraulic motors, first and second hydraulic pumps provided to supply hydraulic oil in correspondence with the first and second hydraulic motors, respectively, first and second swash plate angle sensors provided in correspondence with swash plates which regulate amounts of delivery by the first and second hydraulic pumps, respectively, the first and second swash plate angle sensors each detecting an angle of the swash plate, a delivery amount setting unit which sets an ideal amount of delivery by the first and second hydraulic pumps, and a command value control unit which corrects a command value for adjusting an angle of the swash plate such that the amount of delivery in accordance with a result of detection by the first and second swash plate angle sensors is set to the ideal amount of delivery.

A hydrostatic piston machine has a lifting element that is adjustable for varying a swept volume, and a rotating cylinder part having a plurality of cylinder bores with pistons that are supported on the lifting element and delimit a displacement chamber. Each displacement chamber is moved in an alternating manner by a connecting opening to overlap a low-pressure control opening situated on a low-pressure side of a stationary control part and a high-pressure control opening situated on a high-pressure side of the control part. Two switching regions are situated between the low-pressure control opening and the high-pressure control opening, the pistons changing direction at a dead center within the switching regions. The position of the lifting element is determined from a pressure profile which is a function of the variable size of the displacement chambers in a switching region, the variable size depending on the position of the lifting element.

An axial hydraulic pump-motor, in which a cylinder block having a plurality of cylinder bores on a valve plate having a high-pressure side port and a low-pressure side port for controlling an amount of reciprocation of a piston in each of the cylinder bores, the hydraulic pump-motor includes: a residual pressure release port provided on the valve plate and communicating until the cylinder bore on a top dead center side communicates with the low-pressure side port; a residual pressure acquisition portion obtaining a value of a residual pressure in the cylinder bore on the top dead center side; and a directional switching valve switching a flow path between the residual pressure release port and an hydraulic oil tank and a flow path between the residual pressure release port and the low-pressure side port.

An axial hydraulic pump-motor, in which a cylinder block having a plurality of cylinder bores on a valve plate having a high-pressure side port and a low-pressure side port for controlling an amount of reciprocation of a piston in each of the cylinder bores, the hydraulic pump-motor includes: a residual pressure release port provided on the valve plate and communicating until the cylinder bore on a top dead center side communicates with the low-pressure side port; a residual pressure acquisition portion obtaining a value of a residual pressure in the cylinder bore on the top dead center side; and a directional switching valve switching a flow path between the residual pressure release port and an hydraulic oil tank and a flow path between the residual pressure release port and the low-pressure side port.

An adjusting device for an axial piston machine includes an actuating piston that delimits an actuating space configured to be connected to a control oil source or a control oil drain via a control valve. A control piston of the control valve is loaded firstly by a control spring and secondly by a spring arrangement that is also in active engagement with the actuating piston.

Displacement control device (1) for variably adjusting the displacement of an axial piston hydraulic pump comprising a rotary shaft (10) mounted in a housing (20) and rotatable around a shaft axis (13) of the rotary shaft (10). The rotary shaft (10) having a first end (11) and a second end (12), wherein to the second end (12), which protrudes outside of the housing (20), a torque can be applied for rotating the rotary shaft (10) to open and close servo pressure lines (40, 45) arranged within the housing (20). The servo pressure lines (40, 45) can conduct hydraulic fluid to and from a servo adjusting unit capable to adjust the displacement volume of the axial piston hydraulic pump. The rotary shaft (10) further comprising a mid-portion (14) located between the first end (11) and second end (12). Concentric to the shaft axis (13) in the mid-portion (14) of the rotary shaft (10) a detent sleeve (5) is positioned comprising an abutment area (7) onto which, in the neutral position of the displacement control device (1), a sliding element (8) abuts, which is mounted pre-stressed in the housing exerting a resilient force onto the detent sleeve (5) perpendicular to the shaft axis (13), wherein the detent sleeve (5), in operating conditions of the displacement control device (1) is rotatable fixed with the rotary shaft (10) and turns with the rotary shaft (10). However, for neutral position adjustments in non-operating conditions, the detent sleeve (5) and the rotary shaft (10) are detachable from each other such that the rotary shaft (10) can be turned relative and independently within the detent sleeve (5), which is held in its neutral position by the sliding element (8).

A variable split displacement ratio axial piston machine, featuring a rotatable driveshaft, a tapered swashplate disposed around said rotatable driveshaft, a first working section disposed on a first side of the tapered swashplate, and a second working section disposed on a second side of the tapered swashplate. Each working section includes a respective set of pistons slidably received in a respective set of cylinder bores to draw and expel fluid into and from said cylinder bores. The first and second working sections respectively interface with first and second outer faces of the tapered swashplate in respective first and second facial planes. Tiltable adjustment of a working position of the tapered swashplate is operable to adjust respective orientations of the facial planes, which dictate relative piston stroke lengths of the piston sets. Such tiltable adjustment imparts control over a variable split displacement ratio between the working sections.

A variable split displacement ratio axial piston machine, featuring a rotatable driveshaft, a tapered swashplate disposed around said rotatable driveshaft, a first working section disposed on a first side of the tapered swashplate, and a second working section disposed on a second side of the tapered swashplate. Each working section includes a respective set of pistons slidably received in a respective set of cylinder bores to draw and expel fluid into and from said cylinder bores. The first and second working sections respectively interface with first and second outer faces of the tapered swashplate in respective first and second facial planes. Tiltable adjustment of a working position of the tapered swashplate is operable to adjust respective orientations of the facial planes, which dictate relative piston stroke lengths of the piston sets. Such tiltable adjustment imparts control over a variable split displacement ratio between the working sections.

In an embodiment, a variable flow pump may include a swashplate rotatably driven by a driveshaft. The swashplate may be movable between a first and second tilt angle relative to the driveshaft. A piston pump may be reciprocatingly driven by the swashplate based upon, at least in part, the tilt angle of the swashplate. An actuator piston may be moveable between a first and second position based upon, at least in part, a downstream backpressure of a fluid pumped by the piston pump. An actuator assembly may be moveable between a first and second position based upon, at least in part, the position of the actuator piston. The actuator assembly may include a swashplate driver configured urge the swashplate between the first and second tilt angles, and a biasing driver configured to apply a force urging the swashplate into contact with the swashplate driver.