Multiple safety element torque limiter

Abstract

A displaceable drive ball safety element type torque limiter is installed in a variable speed AC motor drive crusher mill drive which can include a selective operable locking brake to hold the crusher components stationary during maintenance operations.

The invention claimed is: 
     
       1. A torque limiter arrangement in combination with a crusher mill driven by a ring gear and one or more pinion gears each driven by a variable speed AC motor having a driving connection with said crusher mill, said torque limiter including a plurality of plungers held against respective drive balls seated in aligned pockets in respective drive and driven members rotatable with said drive motor and said crusher mill respectively to establish a driving relationship thererbetween, each of said plungers held in engagement by a spring loaded locking ball able to be cammed out of engagement with a respective plunger upon development of a predetermined torque transmitted through said drive balls by said drive and driven members to force said locking balls radially out to a stably maintained disengaged position and allow said drive balls to each be moved out of a respective pocket and thereby discontinue said driving relationship between said variable speed AC motor with said crusher mill;
 said torque limiter further including a selectively operable locking brake connected to said driven member and engaged when said torque limiter is disengaged thereby holding said driven member and crusher mill stationary when said torque limiter is disengaged. 
 
     
     
       2. A torque limiter arrangement in combination with mining machinery driven by a ring gear and one or more pinion gears each driven by a variable speed AC motor having a driving connection with said mining machinery, said torque limiter including a plurality of plungers held against respective drive balls seated in aligned pockets in respective drive and driven members rotatable with said drive motor and said mining machinery respectively to establish a driving relationship therebetween, each of said plungers held in engagement by a spring loaded locking ball able to be cammed out of engagement with a respective plunger upon development of a predetermined torque transmitted through said drive balls by said drive and driven members to force said locking balls radially out to a stably maintained disengaged position and allow said drive balls to each be moved out of a respective pocket and thereby discontinue said driving relationship between said variable speed AC motor with said mining machinery;
 said torque limiter further including a selectively operable locking brake connected to said driven member and engaged when said torque limiter is disengaged thereby holding said driven member and mining machinery stationary when said torque limiter is disengaged.