Kabushiki Kaisha Komatsu Seisakusho

Kenzo Hoashi

Koichi Morita

Nobuaki Inaba

Taketo Aruga

Yasuo Kojima

Kazuo Uehara

Kazuo Matsuda

Hiroshi Takada

A hydrostatic drive arrangement for a vehicle providing synchronized rotation of a pair of output drive shafts including a pair of transmissions each having a closed loop hydraulic circuit hydraulically interconnecting a variable displacement pump and a hydraulic motor, and a pressure responsive hydraulic synchronizing valve disposed between the hydraulic circuits and normally open to permit interflow of fluid between the hydraulic circuits with the valve being responsive to fluid pressure in one of the hydraulic circuits to restrict flow therethrough when the fluid pressure in the one hydraulic circuit exceeds a predetermined value.

Hydrostatic drive arrangement

The known swash plate type oil hydraulic piston pump is improved in that three delivery slots each extending over an angular distance of about 60.degree. are formed in a valve plate along one circumference concentric with a rotary cylinder block at an angular interval of 60.degree. and the number of piston-cylinder units provided in the cylinder block is chosen to be a multiple of 6. Pressurized oil delivered through a center delivery slot is fed to one hydraulic actuator, and pressurized oil delivered through the delivery slots on the opposite sides of the center delivery slot is jointly fed to the other hydraulic actuator, whereby variations of flow rates of the pressurized oil fed to the respective hydraulic actuators can be minimized. Preferably, in order to feed more pressurized oil to a more heavily loaded hydraulic actuator, additional delivery slots are formed in the valve plate at the boundary portions between the three main delivery slots, and pressurized oil delivered through these additional delivery slots is fed selectively to a more heavily loaded hydraulic actuator or, if the both actuators are equally loaded, to both the hydraulic actuator through a pressure-sensitive switching valve. More preferably, a pulsation damper is connected across the hydraulic circuits for feeding the pressurized oil to the respective hydraulic actuators.

Split type oil hydraulic piston pump and pressurized oil feed circuit

A control system for a hydraulically driven vehicle having a pair of closed loop each including a variable displacement hydraulic pump driven by an engine and a variable displacement hydraulic motor, the control system comprising a charge pump driven by the engine, a directional control valve for speed control and forward and reverse change-over of the vehicle connected with the charge pump, a pair of steering valves connected with the directional control valve, a pair of servo controls each operatively connected with the respective variable displacement hydraulic pumps for controlling the displacement volume thereof, another charge pump driven by the engine, and a manually operated selector valve connected with the another charge pump and the servo controls, the selector valve having formed therein a throttling position and a communication position and normally held in the throttling position and being interlocked with the operation of the steering valves, whereby the selector valve is changed-over to its communication position when either one of the steering valves is manually operated.

Control system for hydraulically driven vehicle

A hydraulic circuit for a hydraulically driven vehicle comprising a pair of variable displacement hydraulic pumps, a pair of hydraulic motors each connected with the respective variable displacement pumps in a closed loop, and a straight run compensator valve connected between the respective closed loops for equalizing fluid pressure in both closed loops when the vehicle is set in a straight run thereby assuring a steady straight run of the vehicle irrespective of the difference in displacement of the respective variable displacement pumps.

Hydraulic circuit for a hydraulically driven vehicle

A hydraulic circuit for a hydraulically driven vehicle comprising a pair of variable displacement pumps each driven by a common engine, a pair of variable displacement motors each connected with the respective variable displacement pumps in a closed loop circuit and driven thereby, a fixed displacement charge pump driven by the engine, and a pair of shuttle valves each connected in parallel with the respective closed loop circuits and has formed therein a neutral position and two offset positions wherein in the neutral positions of the shuttle valves both the closed loop circuits are connected with each other through the shuttle valves.

A hydraulic circuit for steering control in articulate vehicles which comprises an engine, a fixed displacement pump driven by the engine, a variable displacement pump driven by the engine, an exit port of the variable displacement pump being connected to a control valve of a steering actuator, an orifice provided at an outlet side of the fixed displacement pump and, a controlling cylinder connected to the variable displacement pump for controlling displacement of the variable displacement pump, the controlling cylinder being actuated by a spring disposed therein and a differential hydraulic pressure at the orifice.

Hydraulic circuit for steering control in articulate vehicles

There is disclosed a method and apparatus for laying small-diameter gas, water pipes or the like precisely in the ground. Small-diameter pilot pipes are first laid in while at the same time, a pilot head is measured and controlled to make its straight advance. Pipes of a larger diameter are then laid in successively, the pipes being led by the pilot pipes. Concurrent with this, excavated earth is discharged through the laid-in pilot pipes.

Method and apparatus for laying pipes in the ground

A hydraulic circuit for controlling actuators in a construction vehicle which comprises an engine, a fixed displacement pump driven by said engine, a variable displacement pump driven by said engine, a controlling cylinder connected to the variable displacement pump for controlling the displacement thereof, an orifice provided between the output of the fixed displacement pump and a tank and, an unloading valve connected to the fixed displacement pump and also to the variable displacement pump via a pilot line for selectively unloading an output fluid from the fixed displacement pump when it is open.

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Yokohama, Japan

Kenzo Hoashi