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:
Dec. 03, 1996
Filed:
Sep. 14, 1994
William H Kohler, Ringwood, NJ (US);
Tec Tran Corporation, Mahwah, NJ (US);
Abstract
A hydraulic pressure control valve uses a stepped valve spool having a differential area exposed to supply pressure to provide a small resultant force on the spool. A linear electric solenoid provides a linearly variable force on the valve spool to variably position the spool. In a basic embodiment, the linear solenoid force opposes the resultant supply pressure force to position the spool and control hydraulic outlet pressure. Other embodiments are employed to control brake pressure in a transit car. In a second embodiment, the resultant hydraulic pressure force is opposed by the linear solenoid force to position the spool during normal service braking. Brake pressure is proportioned to car weight by varying current to the linear solenoid. When the transit car emergency brake pipe is dumped, load weigh air pressure and spring forces position the spool in an emergency brake pressure position proportional to car weight. These forces are normally neutralized by emergency brake pipe pressure during service braking. In a third embodiment, the selectively variable linear solenoid force supplements the resultant pressure force to position the valve spool against the force of a spring and load weigh air pressure. This embodiment provides emergency brake pressure proportional to car weight when electric current is cut off to the solenoid.