GB796785A - Improvements in or relating to clutches - Google Patents

Abstract

796,785. Friction clutches. FICHTEL & SACHS AKT.-GES. Jan. 18, 1955 [Feb. 13, 1954], No. 1471/55. Class 80 (2). A clutch for use in road-building machines, bull dozers and like heavy vehicles, has a friction disc 12 engaged by a member 20 and pressure-plate 4a when a control sleeve 1 is moved to the left of Fig. 2 to tilt three sets of toggle levers 11, 2 to an over-centre position. The clutch is then self-locked in engagement. A support member 3, on which the toggle levers 2 are pivoted, has lugs 6 engaging recesses 15 in the pressure-plate 4a and also engages the inner edge of an annular spring 7 in a ring 9 screwed into a support 5 secured to the member 20. The spring 7 is pretensioned by adjustable screws 10. Weights 16 are provided on the toggle levers 2 to counterbalance the effects of centrifugal force. Lugs 4b on the pressure-plate 4a engage recesses 5a in the support 5. A projection on each toggle lever 2 engages a pressure transmitting bar 8, Fig. 3. The ends of the three pressure transmitting bars 8 are equally spaced circumferentially and are screwed on to the pressure-plate 4a. The axial position of the ring 9 is adjusted by screwing it into the support 5 as the clutch surfaces wear so that the annular spring 7 does not abut the headed ends of the adjusting screws 10 when the clutch is engaged. This causes the degree of pretension of the spring 7 to remain substantially constant between the " clutch engaged " and " clutch disengaged " positions. Springs 14 between the support 5 and pressure-plate 4a bias the clutch to the disengaged position.