Patent GB-377733-A (GB)
Title: Improvements in and relating to automatic friction clutch and transmission
IPC: F16D43/22
Filed: 1931-04-27
Abstract: 377,733. Clutches ; change-speed gearing. BLACKSTOCK, G., 52, Warren Road, Toronto, Canada. April 27, 1931, No. 12404. [Class 80 (ii).] An automatic friction clutch comprises a driving drum 39, Figs. 1 and 2, a floating member 47 and an adjacent or driven member 4 having an arc of mutual freedom, resilient pressure members 52 carried by the member 4 and pivoted shoes 41 on the floating member 47 having friction pads 43 to engage the drum and cam surfaces 44 over which the pressure members 52 run, and means such as a pocket c, Fig. 2, for locking the floating and driven members in the driving position with the shoes 41 pressed on the drum 39 and the clutch thus engaged. As in the arrangement of Specification 353,010, the clutch is disengaged on overload by the roller 52 moving from the pocket c to the position shown in Fig. 2 under the pivot 42 of the shoe 41, and is re-engaged on checking the driving-drum 39 which turns in the direction of the arrow. The incorporation in epicyclic two-speed gearing is described with reference to Figs. 1, 2 and 3, which gearing may be in series with conventional change gearing on a motor-vehicle. The pressure member 52 is supported on a pawl 50 pivoted at 51 upon the driven clutch disc 4 which is part of a planet-carrying drum 3. The pawl 50 comprising a centrifugal weight is thrust out by centrifugal force and by a spring 53 supported on the disc 4. The floating member 47 is loose. Planet gears 15, 16 supported in the drum 3 mesh with sun gears 14, 18 fast on driving and driven shafts 1, 2 respectively. On increased load, the clutch yields and a reduced drive through the gearing is picked up when the drum 3 is prevented from turning backwards by a friction detent shown in Fig. 3. On throttling the engine, solid high-speed driving is resumed. When the drum 3 begins to turn backwards, rollers 21 carried by the drum mount ramps 25 and so thrust friction shoes 26 into firm engagement with a non- rotary abutment drum 32. The shoes 26 are carried centrifugally normally clear of the drum 32 by a floating spider 29. The drum 32 is adapted to be freed to allow reversed driving effected by other gearing by withdrawing locking pins 34 from apertures 35, such withdrawal being effected by the shift lever of the conventional change gearing. There are seals to retain lubricant within the casing 3, Fig. 1, and a safety valve 59 leading excess oil clear of the clutch and detent. An incorporation of the improved clutch in non-epicyclic change gearing is shown in Figs. 7 and 8. A driving-shaft 1 drives a drum 84 direct and a drum 85 at reduced speed through gears 88, 89 and a countershaft. The resilient centrifugal pressure member 79 is carried by a driven shaft (not shown), and a double grip cam shoe 70 is pivoted on the floating member (not shown). On easing the engine, the pressure member 79 turns relatively clockwise into the pocket c holding a friction pad 78 against the faster drum 84. On overload, the member 79 slips back beyond a pivot 75 against a ramp 74 so holding another friction pad 73 against the slower drum 85, thus reducing the drive automatically.