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.

A pump system including a prevention mechanism for preventing excessive fluid temperature buildup of system fluid. The overheat prevention mechanism includes a thermally-responsive control component (130) made with a thermally-responsive material. The thermally-responsive control component is located in the pump system (112) such that the thermally-responsive material is in thermal communication with the system fluid for effecting a change in temperature of the thermally-responsive material. The thermally-responsive material is configured to have an activation temperature that is a predefined amount less than a maximum operating temperature of the system fluid. The thermally-responsive control component is configured to cooperate with a pump control mechanism in the system to decrease pump output pressure in response to the thermally-responsive material being heated by the fluid to a temperature that is equal to or greater than the activation temperature of the thermally-responsive material.

A pump system including a prevention mechanism for preventing excessive fluid temperature buildup of system fluid. The overheat prevention mechanism includes a thermally-responsive control component (130) made with a thermally-responsive material. The thermally-responsive control component is located in the pump system (112) such that the thermally-responsive material is in thermal communication with the system fluid for effecting a change in temperature of the thermally-responsive material. The thermally-responsive material is configured to have an activation temperature that is a predefined amount less than a maximum operating temperature of the system fluid. The thermally-responsive control component is configured to cooperate with a pump control mechanism in the system to decrease pump output pressure in response to the thermally-responsive material being heated by the fluid to a temperature that is equal to or greater than the activation temperature of the thermally-responsive material.

A hydraulic transaxle comprises an axial piston hydraulic pump having a variable displacement, and a transaxle casing incorporating the hydraulic pump. The hydraulic pump includes a movable swash plate and a pair of trunnion shafts. The transaxle casing includes a pair of side walls, and includes a pair of casing holes each of which penetrates each of the side walls between an inside and an outside of the transaxle casing. The pair of trunnion shafts are passed through the respective casing holes. The swash plate is formed with a pair of swash plate holes in the respective side portions facing the respective side walls in the inside of the transaxle casing. Proximal end portions of the respective trunnion shafts are inserted into the respective swash plate holes. A distal end portion of one of the trunnion shafts projects from the corresponding casing hole to the outside of the transaxle casing.

A rotatable piston assembly for a reciprocating piston type hydraulic machine includes a rotatable piston configured for a controlled rotation and configured to reciprocate within a cylinder bore of the reciprocating piston type hydraulic machine.

A rotatable piston assembly for a reciprocating piston type hydraulic machine includes a rotatable piston configured for a controlled rotation and configured to reciprocate within a cylinder bore of the reciprocating piston type hydraulic machine.

Displacement control device for variably adjusting the displacement of an axial piston hydraulic pump including a rotary shaft rotatable around a shaft axis. A torque can be applied for rotating the rotary shaft to open and close servo pressure lines to adjust the displacement volume of the axial piston hydraulic pump. Concentric to the shaft axis in a mid-portion of the rotary shaft a detent sleeve is positioned having an abutment area onto which, in the neutral position, a sliding element abuts. The detent sleeve, in operating conditions is rotatably fixed with the rotary shaft and turns with the rotary shaft and for neutral position adjustments in non-operating conditions, the detent sleeve and the rotary shaft are detachable from each other such that the rotary shaft can be turned relative and independently within the detent sleeve, which is held in its neutral position by the sliding element.

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 method of differentially steering a hydraulically driven vehicle includes measuring left and right swash plate angles of pumps which drive left and right wheels of the vehicle and if the angles are different from one another and the larger swash plate angle is equal to or exceeds a threshold value then reducing the larger swash plate angle. If the larger swash plate angle is between the threshold value and a lower limit, or below the lower limit the swash plate angle is increased. Control systems and vehicles include swash plate angle sensors and actuators in communication with a controller which effects the steering control method.