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. 07, 1993
Filed:
Jul. 15, 1992
Donald D Davis, Rochester, NY (US);
Caldwell Manufacturing Company, Rochester, NY (US);
Abstract
A multiple spring counterbalance includes a torsion spring and a tension spring for exerting a combined lifting force on a window sash. A spiral rod is threadably engaged with a follower nut for converting a torque applied by the torsion spring into a lifting force on the window sash. The spiral rod has a pitch that is varied along one part of its length to produce a substantially constant combined lifting force throughout most of a range of sash travel between a lowered position and an intermediate position. However, the pitch is further varied along another part of the length of the spiral member to produce a larger combined lifting force within a remaining portion of the range of sash travel from the intermediate position to the raised position.