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:
Feb. 29, 2000
Filed:
Apr. 30, 1998
Dale B Childress, Plainfield, IL (US);
Caterpillar Inc., Peoria, IL (US);
Abstract
A variable margin pressure control for a variable displacement load sensing pump comprises a body having a bore therein and a valve spool slidably disposed in the bore defining a chamber in continuous communication with a discharge passage in the body. The valve spool is movable in a first direction for communicating the discharge passage with a control port in the body and in a second direction for communicating the control port with an exhaust flow path. The valve spool is biased in the first direction by discharge fluid pressure in the chamber. A spring mechanism biases the valve spool in the second direction against the force generated by the discharge pressure with a biasing force sufficient to establish a predetermined margin pressure. A remotely controllable variable biasing force is applied against the valve spool by a device so that the margin pressure can be selectively varied in response to receiving a pressure signal. Another devices applies a load pressure generated biasing force against the valve spool in the second direction so that the margin pressure is maintained throughout the pressure operating range of the pump.