Kabushiki Kaisha Kobe Seiko Sho

Kobelco Construction Machinery Co., Ltd.

Kazuhiko Fujii

Tomohiko Asakage

Naoki Sugano

Hideki Kinugawa

Hidekazu Oka

Etsujiro Imanishi

Yutaka Toji

Hiroshi Shimokakiuchi

Yutaka Tohji

Hiroshi Togo

Wataru Kubomoto

Kazuyuki Doi

Masaaki Tachino

Saburo Mori

Tomoshige Tanaka

Sumio Kouchi

A hydraulic circuit including a first throttle disposed upstream of pressure-reducing valves of a remote-control valve, which operates a control valve of hydraulic pilot type, so as to reduce primary pressures supplied from a pilot pump to the pressure-reducing valves. Bleed-off lines connect pilot lines to tanks. Second throttles are disposed on the bleed-off lines, respectively, so as to moderate rises in the pilot pressures supplied to pilot ports of the control valve. The hydraulic circuit prevents detrimental effects such as deterioration of operability while ensuring shock absorption during quick operation.

Hydraulic circuit for construction machine

The prevent invention provides an oil filter comprising a filter element housed in a casing, the filter element being formed of two or more cylindrical element pieces piled on top of another in the height direction and attachably and detachably connected through connecting members. Accordingly, the efficiency in each of manufacture, stock control and storage of the filter element can be improved, and the cost can be also reduced.

Oil filter for construction machine

The present invention relates to a control system and method for a hydraulic working machine characterized by having a construction wherein a flow discharge control valve is disposed in a discharge-side pipe line of a main flow control valve, the amount of operation of an operating lever is converted to a pilot pressure by a remote controlled valve, the pilot pressure is then input to a controller and is calculated into a pressure change speed as operation speed, in a pressure change speed calculator, further, the operation speed is calculated into an electromagnetic valve current in an electromagnetic valve current calculator, then the electromagnetic proportional valve current is output to an electromagnetic proportional valve from a command unit, and the degree of opening of the discharge flow control valve is controlled with a secondary pressure in the electromagnetic proportional valve. According to this construction, it is possible to diminish impact and vibration which occur when there is performed a sudden operation, and also possible to improve the operability for braking and stopping an actuator.

Control system and method for hydraulic working machine

Controlling device for controlling rotational speed of engine of

In a construction machine of a small rotational inertia such as an intrawidth swing machine or a small-sized excavator, a rotative operability varies depending on the posture of a working attachment, and in a reduced state of reach, a change in rotating force is oversensitive to the operation of a working lever, so operation is difficult. To cope with this point, means for detecting the operation of a rotating direction control valve is provided, and an outlet of a center bypassing oil path in the rotating direction control valve and an oil tank are brought into communication with each other through a cut-off valve used for controlling the bleed-off thereof. Further, a pilot port of the cut-off valve and a source of a pilot oil pressure are brought into communication with each other through an electromagnetic proportional pressure reducing valve, and an operation command signal is issued from a controller to the electromagnetic proportional pressure control valve to control the acceleration of rotation and the maximum rotating speed.

Construction machine

An oil hydraulic circuit for a hydraulic shovel with which a composite operation can be performed readily and smoothly without special skill in operation of the hydraulic shovel. The oil hydraulic circuit comprises a first actuator which can operate with pressure oil from a predetermined one or both of a pair of hydraulic directional control valve sets, a second actuator which operates only with pressure oil from the other hydraulic directional control valve set, a proportional changing over device interposed intermediately in a pipe line communicating the other hydraulic directional control valve set with a first actuator for adjusting the maximum meter-in opening value to the first actuator in response to a magnitude of a signal received at a signal receiving portion of the proportional changing over device, and a controller for arbitrarily adjusting the signal to be supplied to the signal receiving portion of the proportional changing over device.

Adjustable flow-combining restrictor for hydraulic excavator dual pump

Described herein is a hydraulic pump control circuit for travelling construction machine, the circuit being of the type including various hydraulic actuators divided into two groups to be driven by first and second pumps, respectively, left and right vehicle drive motors provided in the respective groups, and a change-over valve located on the discharge side of the first and second pumps and switchable to a position for supplying the oil pressure from the second pump in parallel to the left and right vehicle drive motors. According to the invention, the control circuit is provided with a pilot proportioning valve located between a discharge flow rate control regulator for the second pump and a pilot pressure source, and means for applying the pilot pressures acting on left and right vehicle drive valves to pilot ports of the pilot proportioning valve, the proportioning valve being operated by the sum of the pilot pressures applied to the pilot ports to produce a control pressure for the second pump regulator.

Pump discharge flow rate controlled by pilot pressure acting on vehicle

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Hiroshima, Japan

Kazuhiko Fujii