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:
Oct. 28, 1986
Filed:
Feb. 14, 1985
Ronald B Walters, Wembley, GB;
Vickers, Incorporated, Troy, MI (US);
Abstract
A pilot operated relief valve has a main relief valve (10) and a pilot relief valve (31) connected between a control chamber (23) and drain. A restriction (16) connects the control chamber (23) to the inlet chamber (22) which is separated from the control chamber by a piston (24) integral with the main relief valve closure member (12). Thus opening of the pilot relief valve against the adjustable force of a spring (14) determines the maximum pressure in the inlet chamber (22). The control chamber (23) can also be connected to drain (70) by a pilot valve (19) which is operated by a force motor (52) against pressure in a feedback chamber (56) connected to the inlet passage (22). The energization of the force motor (52) can be adjusted to adjust the relief pressure to a value below that at which the pilot relief valve (31) opens. Alternatively the pressure in the feedback chamber (56) can depend on the pressure at at least one side of a load fed via a directional valve from the inlet passage (22).