Worm-gear assembly having a pin raceway

Abstract

A worm-gear assembly including a worm screw having at least one groove and a wheel having a plurality of rotatable pins along its periphery for engaging the worm screw. The pins are able to rotate in a direction other than a direction of wheel rotation. At least one raceway is provided for contacting pins that are not engaged with the worm screw during operation of the assembly.

1 . A worm-gear assembly, comprising: 
 a worm screw having at least one groove;    a wheel having a plurality of rotatable pins along its periphery for engaging the worm screw, the pins being able to rotate in a direction other than a direction of wheel rotation; and    at least one raceway for contacting pins that are not engaged with the worm screw during operation of the assembly.    
   
   
       2 . The worm-gear assembly as recited in  claim 1 , wherein the worm screw has an hourglass shape.  
   
   
       3 . The worm-gear assembly as recited in  claim 1 , wherein the worm screw has a cylindrical shape.  
   
   
       4 . The worm-gear assembly as recited in  claim 1 , wherein the pins are able to rotate about their longitudinal axes.  
   
   
       5 . The worm-gear assembly as recited in  claim 1 , wherein at least one raceway contacts all of the pins that are not engaged with the worm screw.  
   
   
       6 . The worm-gear assembly as recited in  claim 1 , wherein at least one raceway contacts a portion of the pins that are not engaged with the worm screw.  
   
   
       7 . The worm-gear assembly as recited in  claim 1 , wherein the worm screw has one spirally shaped groove.  
   
   
       8 . The worm-gear assembly as recited in  claim 1 , wherein the worm screw has a multiple of spirally shaped grooves.  
   
   
       9 . The worm-gear assembly as recited in  claim 1 , wherein each of the pins has a frustum-shaped head.  
   
   
       10 . The worm-gear assembly as recited in  claim 1 , wherein each of the pins has a head in the shape of a truncated sphere.  
   
   
       11 . The worm-gear assembly as recited in  claim 1 , wherein each of the pins has a head in the shape of a double-truncated sphere.  
   
   
       12 . The worm-gear assembly as recited in  claim 1 , wherein the assembly includes a first raceway and a second raceway, the first raceway contacting pins that are not engaged with the worm screw when the worm screw rotates in a first direction, and the second raceway contacting pins that are not engaged with the worm screw when the worm screw rotates in a second direction.  
   
   
       13 . The worm-gear assembly as recited in  claim 1 , wherein for at least one raceway the surface that contacts pins has a planar cross-section.  
   
   
       14 . The worm-gear assembly as recited in  claim 1 , wherein for at least one raceway the surface that contacts pins has a concave cross-section.  
   
   
       15 . The worm-gear assembly as recited in  claim 1 , further comprising a housing.  
   
   
       16 . The worm-gear assembly as recited in  claim 15 , wherein the housing is a one piece housing.  
   
   
       17 . The worm-gear assembly as recited in  claim 15 , wherein the housing is made up of two or more pieces.  
   
   
       18 . The worm-gear assembly as recited in  claim 15 , wherein at least one raceway is formed as an integral part of the housing.  
   
   
       19 . The worm-gear assembly as recited in  claim 15 , wherein at least one raceway is formed as a separate component that is attached to the housing.  
   
   
       20 . The worm-gear assembly as recited in  claim 1 , further comprising bearings for supporting the pins for rotation in a direction other than a direction of wheel rotation.  
   
   
       21 . The worm-gear assembly as recited in  claim 1 , wherein the pins are arranged in a single row.  
   
   
       22 . The worm-gear assembly as recited in  claim 1 , wherein the pins are arranged in a multiple of rows.  
   
   
       23 . The worm-gear assembly as recited in  claim 1 , wherein the pins are able to rotate about their longitudinal axes in either a clockwise or a counter-clockwise direction.  
   
   
       24 . The worm-gear assembly as recited in  claim 1 , further comprising a shifting mechanism, and wherein the at least one raceway includes a first raceway surface and a second raceway surface, the shifting mechanism being operable to urge pins that are not engaged with the worm screw against the first raceway surface when the worm screw rotates in a first direction and to urge pins that are not engaged with the worm screw against the second raceway surface when the worm screw rotates in a second direction.  
   
   
       25 . A method of operating a worm-gear assembly including a worm screw having at least one groove and a wheel having a plurality of pins along its periphery for engaging the worm screw, the pins being able to rotate in a direction other than a direction of wheel rotation, comprising the step of providing at least one raceway for contacting pins that are not engaged with the worm screw during operation of the assembly.  
   
   
       26 . A method of operating a worm-gear assembly including a worm screw having at least one groove and a wheel having a plurality of rotatably mounted pins along its periphery for engaging the worm screw, comprising the step of providing at least one raceway for contacting at least some of the pins that are not engaged with the worm screw during operation of the assembly.