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:
Jul. 13, 1993
Filed:
Dec. 14, 1992
Joseph E Dezelan, Joliet, IL (US);
Stephen J Tlachac, Naperville, IL (US);
Caterpillar Inc., Peoria, IL (US);
Abstract
Quick drop valves are useful in directing fluid expelled from a contracting chamber of a hydraulic actuator to its expanding chamber under gravity load conditions. The present electro-hydraulic quick drop circuit improves the efficiency of the quick drop valve by energizing a solenoid valve to direct load generated pressure from the rod end chamber of the hydraulic actuators to an end of a quick drop valve for moving the quick drop valve to the quick drop position when a control valve is at or between a preselected intermediate operating position and its fully open position. The quick drop valve is moved to the quick drop position immediately upon the control valve reaching the preselected operating position so that the fluid expelled from the rod end chamber is directed to the head end chamber almost immediately after the blade begins to freefall. Also the quick drop valve totally blocks the rod end chambers from the control valve so that all the fluid expelled from the rod end chambers is directed to the head end chambers at the quick drop position of the quick drop valve.