Torque limiting slip clutch apparatus for cable reel drive assembly

Abstract

A torque limiting slip clutch apparatus for a cable reel drive assembly includes an elongated input drive shaft, annular rotary drive member, annular drive plate, friction generating disc element and biasing force generating spring mechanism. The drive shaft is mounted to undergo rotational movement. The drive member is mounted about the shaft to undergo rotational movement relative to the drive shaft and translational movement along the shaft. The drive plate is fixedly mounted about the drive shaft adjacent to the drive member to undergo rotational movement with the shaft and relative to the drive member. The disc element is mounted between and engagable with the drive member and drive plate to generate friction therebetween that causes rotational movement of the drive member with the drive plate and drive shaft in response to translational movement of the drive member along the shaft toward the drive plate. The spring mechanism is mounted along the drive shaft adjacent to a side of the drive member opposite from the drive plate to generate a biasing force against the drive member causing translational movement of the drive member toward the drive plate and generation of friction between the drive member and drive plate.

What is claimed is:  
     
         1 . A torque limiting slip clutch apparatus for a cable reel drive assembly, said apparatus comprising: 
 (a) an elongated drive shaft mounted to undergo rotational movement;    (b) an annular rotary drive member mounted about said drive shaft to undergo rotational movement relative to said drive shaft and translational movement along said drive shaft;    (c) an annular drive plate fixed mounted about said drive shaft adjacent to said rotary drive member to undergo rotational movement with said drive shaft and relative to said rotary drive member;    (d) means mounted between and engagable with said rotary drive member and drive plate for generating friction therebetween that causes rotational movement of rotary drive member with said drive plate and drive shaft in response to translational movement of said rotary drive member along said drive shaft toward said drive plate; and    (e) means mounted along said drive shaft adjacent to a side of said rotary drive member opposite from said drive plate for generating a biasing force against said rotary drive member to cause translational movement of said rotary drive member along said drive shaft toward said drive plate and generation of friction between said rotary drive member and drive plate.    
     
     
         2 . The apparatus as recited in  claim 1 , wherein said friction generating means includes a disc element having a friction generating material affixed thereon and being attached to a side of said drive plate facing said rotary drive member.  
     
     
         3 . The apparatus as recited in  claim 1 , wherein said biasing force generating means includes a single stack of conical disc springs.  
     
     
         4 . The apparatus as recited in  claim 3 , further comprising: 
 a torque adjustment mechanism disposed adjacent to said biasing force generating means and being operable to adjust the size of the biasing force generated by the biasing force generating means.    
     
     
         5 . The apparatus as recited in  claim 1 , wherein said biasing force generating means includes a plurality of stacks of conical disc springs mounted in equally-distant spaced relationship from one another about said input drive shaft.  
     
     
         6 . The apparatus as recited in  claim 5 , further comprising: 
 a torque adjustment mechanism disposed adjacent to said biasing force generating means and being operable to adjust the size of the biasing force generated by said biasing force generating means.    
     
     
         7 . The apparatus as recited in  claim 1 , further comprising: 
 a torque adjustment mechanism disposed adjacent to said biasing force generating means and being operable to adjust the size of the biasing force generated by said biasing force generating means, said torque adjustment mechanism including 
 (i) a adjustment nut having a periphery with external gear teeth and being mounted about said input drive shaft adjacent to said biasing force generating means to undergo translational movement toward and away therefrom, and  
 (ii) a shaft having a pinion gear at one end and being mounted to undergo reciprocal movement toward and away from said periphery of said adjustment nut so as to move said pinion gear into and out of a meshed driving relationship with said gear teeth on said periphery of said adjustment nut such that when said pinion gear is meshed with said external gear teeth on said adjustment nut rotation of said shaft and said pinion gear therewith causes, depending on the direction of rotation, rotation and translation of said adjustment nut relative to said input drive shaft toward or away from said biasing force generating means so as to correspondingly increase or decrease the biasing force generated on said rotary drive member.  
   
     
     
         8 . A cable reel drive assembly, comprising: 
 (a) a rotary power source operable to provide rotary drive motion at a predetermined input speed;    (b) a cable supply spool storing a cable and being rotatable to payout and rewind the cable; and    (c) a speed reducer unit disposed between and drivingly interconnecting said rotary power source to said cable supply spool and operable in cable payout and rewind rotation modes to cause said cable supply spool to correspondingly payout and rewind the cable, said speed reducer unit including a first speed reduction stage having an input drive shaft and a torque limiting slip clutch, said input drive shaft drivingly coupled to said rotary power source and mounted to undergo rotational movement in response to said rotary drive motion provided at said predetermined input speed by said rotary power source, said slip clutch drivingly coupled to said input drive shaft to undergo rotational movement therewith and operable to receive said rotary drive motion at said predetermined input speed from said input drive shaft and to reduce said rotary drive motion to and provide said rotary drive motion as output at a first speed less than said predetermined input speed.    
     
     
         9 . The assembly as recited in  claim 8 , wherein said speed reducer unit further includes a second speed reduction stage drivingly coupled to said slip clutch of said first speed reduction stage and operable to receive said rotary drive motion at said first speed from said first speed reduction stage and to reduce said rotary drive motion to and provide said rotary drive motion as output at a second speed less than said first speed.  
     
     
         10 . The assembly as recited in  claim 9 , wherein said second speed reduction stage includes means for sensing in which of said cable payout and rewind rotational modes said speed reducer unit is operating at any given time to cause shutoff of operation of said rotary power source in response to sensing said cable payout rotational mode but not said cable rewind rotational mode to thereby enable said slip clutch to function as a slip brake restraining the rotation of said cable supply spool to the speed at which the cable is pulled from said cable supply spool by movement of machinery connected to the cable and to function as a holding brake preventing further rotation of said cable supply spool when movement of the machinery has ceased.  
     
     
         11 . The assembly as recited in  claim 9 , wherein said second speed reduction stage includes: 
 an intermediate shaft, and    first and second rotary members of different diameters disposed adjacent to and connected with one another and mounted about said intermediate shaft in order for said first and second rotary members together to undergo rotational movement, said first rotary member being drivingly coupled to said slip clutch of said first speed reduction stage to receive said rotary drive motion therefrom at said first speed and such that said rotary drive motion is reduced by said first rotary member to a second speed less than said first speed and provided as output at said second speed by said second rotary member.    
     
     
         12 . The assembly as recited in  claim 11 , wherein said second speed reduction stage further includes means for sensing in which of cable payout and rewind rotational modes said speed reducer unit is operating at any given time to cause shutoff of operation of said rotary power source in response to sensing said cable payout rotational mode but not said cable rewind rotational mode to thereby enable said slip clutch to function as a slip brake restraining the rotation of said cable supply spool to the speed at which the cable is pulled from said cable supply spool by movement of machinery connected to the cable and to function as a holding brake preventing further rotation of said cable supply spool when movement of the machinery has ceased.  
     
     
         13 . The assembly as recited in  claim 9 , wherein said speed reducer unit further includes a third speed reduction stage drivingly coupled to said second speed reduction stage and operable to receive said rotary drive motion at said second speed from said second speed reduction stage and to reduce said rotary drive motion to and provide said rotary drive motion at a third speed less than said second speed and thereby rotate said cable supply spool to correspondingly payout and rewind the cable at said third speed.  
     
     
         14 . The assembly as recited in  claim 13 , wherein said third speed reduction stage includes: 
 an output shaft mounted to undergo rotational movement, said cable supply spool being fixedly mounted to and about said output shaft to undergo rotational movement therewith; and    a rotary driven member axially spaced from said cable supply spool and fixedly mounted to and about said output shaft to undergo rotational movement therewith, said rotary driven member being drivingly coupled to said second rotary member of said second speed reduction stage to receive said rotary drive motion therefrom at said second speed and cause said output shaft and cable supply spool to reduce said rotary drive motion to a third speed less than said second speed and thereby payout and rewind the cable at said third speed.    
     
     
         15 . The assembly as recited in  claim 8 , wherein said torque limiting slip clutch of said first speed reduction stage includes an annular rotary drive member mounted about said input drive shaft to undergo rotational movement relative to said input drive shaft and translational movement along said input drive shaft.  
     
     
         16 . The assembly as recited in  claim 15 , wherein said torque limiting slip clutch further includes an annular drive plate mounted about said input drive shaft adjacent to said rotary drive member to undergo rotational movement with said input drive shaft and relative to said rotary drive member.  
     
     
         17 . The assembly as recited in  claim 16 , wherein said torque limiting slip clutch further includes means mounted between said rotary drive member and drive plate for generating friction therebetween that causes rotational movement of said rotary drive member with said drive plate and drive shaft in response to translational movement of said rotary drive member along said drive shaft toward said drive plate.  
     
     
         18 . The assembly as recited in  claim 17 , wherein said friction generating means includes a disc element having a friction generating material affixed thereon and being attached to a side of said drive plate facing said rotary drive member.  
     
     
         19 . The assembly as recited in  claim 17 , wherein said torque limiting slip clutch further includes means mounted along said shaft adjacent to a side of said rotary drive member opposite from said drive plate for generating a biasing force against said rotary drive member to cause translational movement of said rotary drive member along said drive shaft toward said drive plate and generation of friction between said rotary drive member and drive plate.  
     
     
         20 . The assembly as recited in  claim 19 , further comprising: 
 a torque adjustment mechanism disposed adjacent to said biasing force generating means and being operable to adjust the size of the biasing force generated by said biasing force generating means.    
     
     
         21 . The assembly as recited in  claim 19 , wherein said biasing force generating means includes a single stack of conical disc springs.  
     
     
         22 . The assembly as recited in  claim 21 , further comprising: 
 a torque adjustment mechanism disposed adjacent to said biasing force generating means and being operable to adjust the size of the biasing force generated by said biasing force generating means.    
     
     
         23 . The assembly as recited in  claim 19 , wherein said biasing force generating means includes a plurality of stacks of conical disc springs mounted in equally-distant spaced relationship from one another about said input drive shaft.  
     
     
         24 . The assembly as recited in  claim 23 , further comprising: 
 a torque adjustment mechanism disposed adjacent to said biasing force generating means and being operable to adjust the size of the biasing force generated by said biasing force generating means.