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:
Oct. 08, 1991
Filed:
Aug. 17, 1990
Tracy G Rogers, Rochester, NY (US);
Schlegel Corporation, Rochester, NY (US);
Abstract
An apparatus for offsetting a constant force over a range of movement, includes a power spring or clock spring, defined by a length of resilient material wound in a spiral, the opposite ends of which are attached relative to one of the force and a fixed point, and to a pulley. The pulley is substantially coaxial with the spring and has a rounded outer contour defining a progressively varying slope proceeding axially along the pulley. A flexible cord wraps around the pulley and leads to the other of the force and the fixed point. The opposite (inner and outer) ends of the spring can be mounted such that the inner end of the spring is fixed relative to the fixed point and the outer end of the spring is attached to the pulley. The constant force can be the weight of a window sash, movable vertically in a frame. The rounded outer contour of the pulley defines a curve corresponding to an increase in torque of the spring with displacement, due to decrease in radius of the spring and decrease in active length of the spring with binding of inner wraps of the spiral.