Patent GB-330039-A (GB)
Title: Improvements in and relating to power transmission mechanism
IPC: F16D23/08
Filed: 1929-03-26
Abstract: 330,039. Alltree, A. March 26, 1929. Divided on 331,293. Clutches, claw; facilitatingchanging speed.-In claw clutches for automatically coupling two members, such as shafts, chain-wheels, or a shaft, and chain-wheel, when they are in approximate synchronism, an internally-disposed grooved bar or splined sleeve is provided so to coact with the two members as to prevent clutching until they run at substantially the same speed. The invention is particularly applicable as an isolating- clutch behind the gear-box of a motor vehicle. A claw member c, Fig. 1, slidable on the driven or propeller shaft b and adapted to engage a member d fast on the driving or gear-box shaft a, is provided with a peg c<2> engaging a helical or axial slot e<1> in a bar e, which is pressed by a ball f<1> and spring f and is coned to engage a recess in the shaft a. When the clutch is disengaged and the shaft b overruns, the peg c<2> enters a circumferential recess e<2> at the end of the slot e<1>. The clutch cannot then re-engage under its spring not shown) until the shaft a overtakes and frictionally rotates the bar e. A second recess e<3>, Fig. 9, either aligned with the recess e<2> or staggered therefrom, as shown, may be provided to prevent clutch engagement when shaft a runs ahead of shaft b. The bar e may be replaced by a sleeve h, Figs. 5 and 6, revoluble on a reduced part a<1> of the shaft a and provided with splines h' having recessed ends h<3>. When clutch member c is withdrawn and overruns, the splines thereon engage the recesses h<3>, due to the drag on the sleeve h of a single or multiple coil spring band i, secured at i<1> to the member d. The band i is so coiled as to give minimum grip when the vehicle is coasting and maximum grip when the sleeve h is being restored to allow clutch engagement. Supplementary recesses, opposed to and either aligned with the recesses h<3> or not, may be provided as before. In a modification, Fig. 7 (not shown), the driven member has internal dogs engageable alternatively with one set of external driving-dogs, when permitted by the grooved bar or splined sleeve, or with a secondary emergency set, if recoupling is desired irrespective of want of synchronism, as when using the momentum of the vehicle to restart the engine. Fig. 12 shows a modification for coupling a driving-sprocket o to a sleeve j, which may carry a driven sprocket o<1>. The sleeve is splined at j<2>, j' to carry respectively the hub l of sprocket o' and the sliding clutch member c, and has a plain portion on which are mounted the dog-toothed hub k of sprocket o, the splined and recessed sleeve h, and the spring band i. In any of the constructions, the sliding part may be actuated from the main clutch pedal, the gear-lever, or directly from the sliding part of the main friction clutch by are disposed in the hollow gear-shaft and having cross-pieces projecting therethrough to engage the clutch members. The sliding claw-clutch element may be the driving-member. The second Provisional Specification describes also a form in which the internal splines on the sliding member coact with splines on the driving-shaft when the clutch is engaged, the dogs being omitted, and a further form in which the loose intermediate member has dogs with terminal seatings coacting with the sliding dog-clutch member. The means for imparting a drag to the intermediate member may comprise a spring-loaded arm, sleeve, or ring. The application of the invention to the final-drive sprocket of a motor-cycle is mentioned.