GB900035A - Improvements relating to tools for fitting and removing the valve cores of pneumatic tyres and other inflatable articles - Google Patents

Abstract

900,035. Screwdrivers. DUNLOP RUBBER CO. Ltd. Oct. 20, 1958 [Nov. 28, 1957], No. 37064/57. Class 61. A tool for fitting and removing the valve core of a pneumatic tyre or other inflatable article comprises a key part 2 for insertion into the valve barrel to engage the core, and a clutch part which comprises a cylindrical member 6 axially slidable and rotatable within a tubular handle 1 and having a pair of semi-circular part-helical teeth 9 at one end, each terminating in an abrupt longitudinal edge dropping to the commencement of the other tooth, and a driving part which comprises a transverse bar 5 secured across the tubular handle 1, the clutch part 6 being urged by a compression spring 10 towards the bar 5 and connected to the key part 2 which projects axially from the handle 1, the slope of the teeth 9 and the strength of the spring 10 being such that on rotating the handle 1 to turn the key in the inserting direction the bar 5 will ride on the helical teeth 9, but if the torque transmitted exceeds the predetermined value it will ride over them, depressing the clutch part 6 against the spring 10; and on rotating the handle 1 in the other direction the bar 5 will engage the longitudinal edges of the teeth 9 so as to transmit a greater torque without depressing the clutch part 6. The lower end of the spring 10 abuts against a plug 11 secured to the handle 1. The maximum torque is set by inserting a predetermined number of washers 13 between the spring 10 and plug 11. In a modification shown in Fig. 4, a key part 20 is rotatably anchored in the end of a tubular handle 21 by means of a flange 22. The stem 23 of the key part 20 is formed with a series of radially disposed ratchet teeth 25 which engage complementary teeth on a driving part 26. The part 26 is slidably but non-rotatably keyed with a handle 21 by a peg 27 engaging in a slot 28 in the handle. A spring 38 urges the driving part 26 into engagement with the teeth 23. The torque will be limited in the " insertion " direction by the teeth riding over each other against the action of the spring 38. A greater torque can be given in the " removal " direction since the torque is transmitted through the abutting longitudinal faces of the teeth.