06720873 is referenced by 7 patents.

A device for testing a cable deroped magnetic proximity detector positioned adjacent a cable sheave or sheave assembly on a cable operated ski lift. A sleeve of non-ferromagnetic material is temporarily secured coaxially over the steel lift cable and the sleeve is dimensioned in length and thickness in amounts sufficient to raise the cable simultaneously away from the detector and the adjacent sheaves whereby the detector indicates a derope condition. When the ski lift is operated to thereby move the sleeve over the detector and adjacent sheaves, a derope condition will be simulated and the alarm tested to determine whether it provides the appropriate signal.

Title
Method and apparatus for testing magnetic proximity detectors on ski lifts
Application Number
10/377554
Publication Number
6720873 (B1)
Application Date
March 3, 2003
Publication Date
April 13, 2004
Inventor
Brett D Tressler
704 Sterner St., Confluence
PA, US
Agent
Carothers & Carothers
US
IPC
G08B 29/00
View Original Source