GB689942A - - Google Patents

Abstract

689,942. Controlling clutches. NATIONAL CASH REGISTER CO. April 16, 1951 [April 20,1950], No. 8774/51. Class 80 (ii). A contracting coil clutch comprises a spring 20 of rectangular section so wound that in its free state it will grip the outer surface of a driving member 13, a stop 27 being movable into the path of one end of the spring to release the clutch. One end of the coil 20 is secured to a collar 21 attached to a driven member 14 which carries a pinion 16, the collar 21 extending at 22 substantially over the length of the coil 20. The driving member 13, which is driven through worm gearing 11, 12, is mounted coaxially with the member 14 on a stud 17 and its surface is grooved at 35 to increase the coil grip and, by retention of lubricant, to reduce wear. The stop 27, which is carried by a plate 24 rotatably mounted on the collar 21, comprises a portion 36 adapted to engage the end 31 of a pivoted lever 32 in the released position of the clutch shown in Fig. 1. The end 31 is bifurcated and also engages a shoulder on a plate 30 fixed to the collar 21 in order to locate definitely the driven member when stationary. A torsion spring 28 surrounding the portion 22 of the collar 21 acts at one end on the stop 27 and at the other on a stud 29 carried by the plate 30 to tend to move the stop away from the end of the coil 20 which would then be free to grip the driving member. A stop 34 on the plate 24 limits relative movement of the plates 24, 30 by engaging the stud 29. When a spring 45 is allowed, by rotation of a release shaft 40 in known manner; to rotate the lever 32 out of engagement with the portion 36, the spring 28 rotates the plate 24 thereby moving the stop 27 to allow the coil 20 to engage the driving member, and also by means of a cam portion 50 of the plate rotates a lever 52 to close contacts 59, 60 and energise the driving motor. A roller 51 on the arm 52 spans and follows the peripheries of the plates 24, 30 thus maintaining the motor circuit closed until the lever 32 is restored (in known manner) to the position shown. When the portion 36 abuts the end 31 of the lever 32 the plate. 24 is arrested and the clutch is freed but the plate 30 continues to rotate, stressing the spring 28, until the shoulder thereon also abuts the end 31 and the roller 51 rides down a cam portion 65 of the plate 30 to allow the contacts 59, 60 to open and stop the driving motor.