The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 16, 1986
Filed:
Aug. 30, 1984
Kabushiki Kaisha Komatsu Seisakusho, Tokyo, JP;
Abstract
A hydraulic circuit is disclosed for driving a bidirectional hydraulic motor from a pump via a hand operated directional control valve, as for propelling an earthmover or actuating an implement assembly thereon. For mitigating an abrupt pressure rise as when the motor is set into or out of rotation, the circuit has a pair of oppositely directed dual pressure relief valves connected in parallel with each other between a pair of main lines extending between motor and directional control valve. Each dual pressure relief valve is normally conditioned to pass at a predetermined lower pressure the pressurized fluid from one of the main lines and to pass at a predetermined higher pressure the pressurized fluid from the other main line. When pilot operated from a timing valve responsive to a pressure differential between the main lines, that one of the relief valves which has been bleeding off the pressurized fluid at the low pressure is closed, with the result that the pressurized fluid is then released at the high pressure through the other relief valve, thereby causing two stepwise pressure rises for the reduction of a shock. The invention proposes the provision of a variable resistor between the timing valve and each main line for variably delaying the pilot actuation of the relief valves by the timing valve.