GB867335A - Improvements relating to clutch mechanisms - Google Patents

Abstract

867,335. Operating clutches. KOEHRING CO. Oct. 30, 1957 [Oct. 30, 1956], No. 33899/57. Class 80 (2). An internal expanding clutch band 1, Figs. 1 and 2, adapted to engage a driven clutch drum 2 of, for example, a cable drum, is carried by a spider 7 secured to a hub 8 splined to a driving- shaft 4. The band 1 is anchored to the spider 7 at one end 9 whilst the other end is actuated by a lever 12 and a toggle 14 having a compensator spring 18 to compensate for expansion or contraction of the clutch drum 2 due to variations in operating temperature. The toggle 14 is adapted to be actuated to engage the clutch by relative rotation of a drum 29 to the frame 7 against a spring 51 by the application of an external brake band 32, Figs. 2 and 4, thereto. The band 32 is anchored at one end 33 to a stationary frame 34 whilst the other end 37 is coupled to the forked end 41 of a differential lever 42, the other end 57 of which is supported by a shift-fork member 52. Intermediate its ends the lever 42 is coupled by a pin 28 to a lever 24 connected by a linkage 22 to a manual control lever 21. The fork member 52 is pivoted at 53 and engages in a peripheral groove in a sleeve 62 axially slidable on the driving-shaft 4. The sleeve 62 carries a cam follower 63 cooperating with an arcuate cam 67 carried by the drum 29 so that on initial operation of the control lever 21 both ends 41, 57 of differential lever 42 move upwards to apply the brake band 32 and to move, through fork 52, the cam follower 63 against the cam 67. The braking of the drum 29 by bond 32 effects an angular displacement relative to the driving-shaft and spider 7 to operate the toggle 14 by a link 47 to apply the clutch band 1 to the drum 2. The relative movement of drum 29 allows cam follower 63 to move and operate fork 52 to raise the end 57 of differential lever 42 to tend to release the brake band 32 and provide a feed-back movement to the control lever 21. The lever 21 has to be moved further to obtain a further degree of clutch engagement. The clutch can be locked in a position of full engagement by the cam follower 63 engaging behind the end 69 of cam 67. Reverse movement of the control lever will release the cam follower and progressively release the brake band 32 until the clutch is fully disengaged.