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:
Apr. 28, 1992
Filed:
May. 17, 1991
Eugene R Jornod, Caledonia, IL (US);
Lary L Field, Argyle, IL (US);
Gerald R Parsons, Loves Park, IL (US);
Barber-Colman Company, Rockford, IL (US);
Abstract
The piston of a reciprocating hydraulic actuator carries a pump which is driven by an electric motor and which supplies oil from the low pressure chamber of a cylinder to the high pressure chamber thereof in order to advance the piston. An exhaust valve in the piston is normally held in a closed position by magnetic force created by energizing a coil and, when closed, enables pressurization of the high pressure chamber of the cylinder. When a second coil is energized, the magnetic field of the first coil is negated and the valve is opened by a spring to permit oil to exhaust from the high pressure chamber to the low pressure chamber and permit a second spring to retract the piston. If both the pump motor and the second coil are de-energized, the first coil keeps the valve closed and causes the piston to remain in a commanded position. The actuator may be controlled by a floating single pole, double throw switch and its piston is automatically shifted to its fully retracted position by the second spring if electrical power to the actuator is lost.