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:
Sep. 25, 2001
Filed:
Sep. 21, 1999
Thomas J. Hajek, Jr., Lockport, IL (US);
Srikrishnan T. Tolappa, Aurora, IL (US);
Daniel T. Mather, Lockport, IL (US);
Caterpillar Inc., Peoria, IL (US);
Abstract
A control system is provided with a float condition to permit a double acting hydraulic cylinder to freely extend or retract in response to external forces acting on the hydraulic cylinder. The system includes a pair of pilot operated poppet valves disposed between the opposite sides of the hydraulic cylinder and a directional control valve. The pilot condition is obtained by opening a pair of pilot operated control valves to vent the control chambers of the poppet valves to a tank through a pair of float check valves. The float check valves are operative to prevent higher pressure fluid from being transmitted from the tank to the control chambers of the poppet valves when a negative pressure occurs in the side of the hydraulic cylinder that is connected to the control chamber.