Means for yieldably coupling a shaft to counter wheels or the like

Abstract

A meter, counter, printer or a like device wherein a shaft carries one or more wheels whose angular position with respect to the shaft must be changed, either at regular or irregular intervals. The peripheral surface of the shaft has an elongated recess which is parallel to the axis of the shaft. The inner portion of the recess receives an elongated elastic cushion, and the outer portion of the recess confines the major portion of a helical spring with spaced-apart convolutions. The smaller portion of the spring extends into a selected socket in the internal surface of a wheel or into selected sockets in the internal surface of two or more wheels which surround the shaft. The angular positions of the wheels can be changed by rotating the shaft relative to a selected wheel or vice versa with a predetermined torque which suffices to expel the smaller portion of the spring from the socket of the selected wheel by simultaneous deformation of the elastic cushion whereupon the cushion expands and propels the smaller portion of the spring into another internal socket of the selected wheel when the other socket moves into register with the recess. The deformation of the spring in response to rotation of a selected wheel relative to the shaft or vice versa is limited to the region of the selected wheel so that the angular positions of the remaining wheels relative to the shaft remain unchanged.

I claim: 
     
       1. In a device for applying or exhibiting indicia, the combination of a shaft having a peripheral surface and a recess provided in said peripheral surface and extending in parallelism with the axis of the shaft; at least one wheel having an internal surface rotatably surrounding said shaft and provided in said internal surface with at least two sockets which are spaced apart from each other, as considered in the circumferential direction of said shaft; and means for yieldably coupling said wheel to said shaft, including a helical spring extending in parallelism with the axes of the shaft and having a first portion in said recess and a second portion projecting from said recess and normally extending into one of said sockets, said internal surface having means thereon which will result in said second portion being expelled from said one socket to penetrate at least in part into said recess in response to the application of a predetermined torque to said shaft in a direction to rotate the latter relative to said wheel or vice versa and said second portion of said spring being free to enter the other of said sockets when said other socket registers with said recess. 
     
     
       2. The combination of claim 1, further comprising an elastic cushion installed in said recess inwardly of said first portion of said spring, as considered radially of said shaft. 
     
     
       3. The combination of claim 2, wherein at least a portion of said cushion consists of rubber. 
     
     
       4. The combination of claim 2, wherein at least a portion of said cushion consists of synthetic plastic material. 
     
     
       5. The combination of claim 2, wherein said cushion has a substantially rectangular or square cross-sectional configuration in the undeformed condition thereof. 
     
     
       6. The combination of claim 1, wherein said spring has a plurality of convolutions and the neighboring convolutions are spaced apart from each other. 
     
     
       7. The combination of claim 1, wherein said recess is open at both ends of said shaft and the length of said spring at least approximates the length of said recess. 
     
     
       8. The combination of claim 1, wherein said spring includes two end convolutions and at least a portion of each end convolution is located in a plane which is substantially normal to the axis of said spring. 
     
     
       9. The combination of claim 8, wherein said portions of said end convolutions constitute approximately 50 percent of the respective end convolutions. 
     
     
       10. The combination of claim 1, wherein the outer diameter of said spring is between two and three millimeters. 
     
     
       11. The combination of claim 1, wherein the diameter of the wire of said spring is between one-fourth and one-half of one millimeter. 
     
     
       12. The combination of claim 1, wherein said spring comprises a plurality of convolutions and the neighboring convolutions are spaced apart from each other, the spacing between such neighboring convolutions being equal to or approximating the diameter of the wire of said spring. 
     
     
       13. The combination of claim 12, wherein said spacing is between one-half and one-fourth of one millimeter. 
     
     
       14. The combination of claim 12, wherein said spacing is approximately 0.35 millimeter. 
     
     
       15. The combination of claim 1, wherein the lead of said spring is between 5 and 10 degrees. 
     
     
       16. The combination of claim 1, wherein the lead of said spring is approximately 7.5 degrees. 
     
     
       17. The combination of claim 1, wherein said recess has a width, as considered in the circumferential direction of said shaft, which approximates the outer diameter of said spring. 
     
     
       18. The combination of claim 17, wherein said recess has a portion of reduced width at said peripheral surface so that said first portion of said spring is held against accidental withdrawal from said recess. 
     
     
       19. The combination of claim 18, wherein said first portion is the larger portion of said spring. .Iadd. 
     
     
       20.  In a printer, a plurality of axially aligned wheels, each having a plurality of different printing elements coupled thereto, a support for rotatably supporting said wheels, said wheels having holes defining a continuous opening, each of said wheels also having a series of recesses, detenting means including a metal helical spring engaging a plurality of said wheels for detenting the wheels, said detenting means including means providing a recess in said support, said recess in said support having an open side, said helical spring being disposed in said recess in said support and projecting beyond the open side into one recess in each wheel to detent the wheels and align selected printing elements at a printing zone. .Iaddend. .Iadd.21. A printer as in claim 20, wherein the recesses in said wheels have inclined surfaces cooperable with said helical spring to cam selected printing elements to printing positions. .Iaddend. .Iadd.22. The printer defined in any of claims 20 or 21 wherein the helical spring is of one-piece construction. .Iaddend. .Iadd.23. The printer defined in any of claims 20, 21 or 22 wherein the helical spring is composed of wound wire and has a diameter substantially less than the thickness of a wheel. .Iaddend. .Iadd.24. In a device for applying or exhibiting indicia, the combination of a plurality of axially aligned wheels, a supporting surface for said wheels coaxial therewith, a supporting surface recess provided in said supporting surface and extending in parallelism with the axis of said wheels, each wheel having at least two wheel recesses spaced apart circumferentially of said wheel, and means for yieldably coupling said wheels to said support surface, including a helical spring extending in parallelism with the axis of said wheels and having a first portion in said supporting surface recess and a second portion projecting from said supporting surface recess and normally extending into one of said wheel recesses, said wheels having means thereon adapted to expel said spring second portion from one wheel recess of a wheel to penetrate at least in part into said supporting surface recess in response to the application of a predetermined torque to said wheel, said second spring portion being free to enter another wheel recess of the wheel when the latter wheel recess is in register with said supporting surface recess. .Iaddend. .Iadd.25. The combination of claim 24 further comprising an elastic cushion in said surface recess behind said first spring portion. .Iaddend. .Iadd.26. The combination of claim 25 wherein at least a portion of aid cushion consists of a rubbery material. .Iaddend. .Iadd.27. The combinaion of claim 25 wherein said cushion has a substantially rectangular cross-sectional configuration when undeformed. .Iaddend. .Iadd.28. The combination of claim 24 wherein said spring has a plurality of convolutions, and the neighboring convolutions are spaced 
     
     
        apart from each other. .Iaddend. .Iadd.29.  The combination of claim 24 wherein said spring has a length approximately equal to the length of said recess in an axial direction. .Iaddend. .Iadd.30. The combination of claim 24 wherein said surface recess has a circumferential width approximately equal to the outer diameter of said spring. .Iaddend. .Iadd.31. The combination of claim 24 wherein said surface recess has a portion of reduced width at said supporting surface so that said spring is held against accidental withdrawal from said surface recess. .Iaddend. .Iadd.32. The combination as in claim 24 wherein said support surface is the outer surface of a shaft, said wheels being in the form of rings rotatably supported on said shaft, and said wheel recesses are on the surfaces of said wheel rings. .Iaddend. .Iadd.33. An invention as in claim 20 including means for engaging and rotating any selected wheel to bring a selected printing element to a printing zone. .Iaddend.