GB970041A - Improvements in or relating to geared mechanisms - Google Patents

Abstract

970,041. Toothed gearing. S. DAVALL & SONS Ltd., and R. W. G. SOMERVELL. Oct. 6, 1960 [Nov. 27, 1959], No. 40398/59. Heading F2Q. Apparatus for avoiding or reducing backlash between a driven wheel 12 and a driving wheel 11 comprises a spring 24 to bias the wheel 12 anticlockwise into engagement with the wheel 11, the spring being coupled to the wheel 12 by a coupling which allows lost motion between the spring 24 and the wheel 12 when the wheel is rotated clockwise but not when the rotation is anticlockwise. Cams 14 and 15 are freely pivoted to the spindle 13 of the driven wheel 12 the arm 15 being urged anticlockwise by the spring 24. Fixed to the arm 15 is a friction pad 19 which is urged, by means of a spring 21, into contact with a rotatable wheel 18, a pinion 17, in contact with the wheel 12, being fixed coaxially with the wheel 18. When the wheel 12 is initially driven clockwise the wheel 15 and pad 19 are in firing contact, the pinion 17 is thus locked, and the arms 14 and 15 rotate with the wheel 12. The tension in the spring 24 soon becomes greater than that in the spring 21, and the arms separate slightly to allow rotation of the wheel 18 and hence the pinion 17, a position of equilibrium thus being reached. The torque exerted by the spring 24 is maintained when the driving wheel 11 is slowed or stopped, thus backlash is reduced between the wheels 11 and 12. The wheel 11 can be given slight reverse rotation without upsetting the spring bias, and the arm 15 can, if desired, be allowed to contact a stop 26 during normal operation, before a state of equilibrium is otherwise reached.