Abstract: A variable displacement hydraulic motor is easily mounted on a power shovel without interfering with a truck frame of the power shovel and without projecting outward therefrom. The hydraulic motor is easily assembled and machined in its manufacturing. In the hydraulic motor (M'), there is provided an end cover (57) in which is slidably mounted a piston lever (69) which is oppositely disposed from a drive shaft (44) of the hydraulic motor (M') to extend in a direction perpendicular to an axis of the drive shaft (44). Since the hydraulic motor (M') is provided with a valve plate swinging unit having a pin (71) through which the piston lever is connected with a valve plate (59) fixedly mounted on a cylinder block (60), it is possible to directly mount the end cover (57) on a main casing (50) of the hydraulic motor (M') so as to be perpendicular to the axis of the drive shaft (44).

Abstract: The heretofore known adjusting device for an axial piston pump/motor of a tilting axis type in which a tilt angle of a valve plate is varied by rocking the valve plate along arcuate guide grooves formed in an end cover of the axial piston pump/motor is improved so as to reduce the size of the adjusting device in the direction of its stroke by assembling a sleeve or sleeves and a piston fitting in the sleeve or sleeves in a telescopic structure within a cylinder formed in the end cover along a rocking direction of the valve plate, and by providing a trunnion pin engaged with the valve plate in the piston.

Abstract: A fluid pressure control circuit for operating a bidirectional hydraulic motor comprises first and second main conduits for selectively supplying the pressurized fluid delivered by a main hydraulic pump through a pilot fluid pressure operated three-position directional control valve and via a brake valve device into first and second ports of the bidirectional hydraulic motor; two pilot fluid supply conduits located in parallel relationship with each other for selectively supplying the pressurized fluid delivered by an auxiliary hydraulic pump as a pilot fluid pressure through a three-position directional control valve into the left and right pressure receiving portions of said pilot fluid pressure operated three-position directional control valve; a conduit for selectively supplying the pressurized fluid delivered by the auxiliary hydraulic motor through a solenoid operated control valve into the pressure chamber of a gyratory brake device; and a conduit for short-circuiting said two pilot fluid supply condui

Abstract: A spring applied and hydraulically released motor shaft brake apparatus for a hydraulic motor which is compact in size. The brake apparatus includes a piston slidably mounted in a cylinder defining a brake chamber and a drain chamber. The piston is slidably and rotatably mounted on the motor shaft and a spring is disposed in the drain chamber for biasing the piston towards the brake chamber to thereby lock the motor shaft against rotation. The brake chamber is selectively connectible with a pressurized fluid source while the drain chamber is connected with a drain. The piston has formed therein a passage with a restrictor disposed therein for restricting flow of fluid in the passage.

Abstract: A control system for a hydraulically driven vehicle having a variable displacement hydraulic motor connected with a variable displacement hydraulic pump in a closed loop and driven thereby.A spring-applied and fluid-released brake is mounted on an output shaft of the motor. A regulator is operatively connected to the motor for controlling the displacement thereof in response to a fluid pressure at both ports thereof. When fluid pressure at either one of the ports of the motor exceeds a predetermined level, the variable displacement motor is changed over to a high displacement position thereby generating a large braking force when the vehicle is to be stopped.