GB299230A - A new or improved electro-magnetic key clutch or ratchet clutch - Google Patents

Abstract

299,230. Bain, R., and Fenton, J. Dec. 24, 1927. Clutches, positive and ratchet.-A clutch ior driving a shaft from a disc or wheel loose thereon comprises a radially-movable electromagnetic key adapted, on momentary energization of the electromagnet coil, to be attracted by the shaft and engage a ratchet tooth thereon, and to be disengaged by overrunning the shaft. The driven shaft 10, Fig. 1, has one or more spiral grooves 11 or spiral projections forming a ratchet tooth or teeth 13, and carries loosely a gunmetal or other non-magnetic disc 14, which supports a toothed steel ring 21 and has a covered recess 15 for the magnet coil 18 and the clutch-key 12 forming the slidable core thereof. On closing the coil circuit through slip rings (not shown) and contacts 30, 31 on the ring 21 and disc 14 respectively, the key 12 normally retracted by centrifugal force aided by a spring 17, is attracted to the shaft as soon as the tooth 13 passes under it, and finally abuts against the tooth face. The ring 21 and disc 14, being connected by a lug 20 and yielding spring 22, are then relatively displaced to carry the contact 30 over an insulating segment 42 and to bring lugs 29 over the end of the key 12. The centrifugal force on the key 12 is largely balanced by the pressure thereon of the end 32 of a weighted lever 24, which is pivoted at 25 and lies in a recess 23, 27 in the disc and in a groove 28 in the ring. Excessive pressure of the lever 24 on the key in the engaged position is relieved by its contacting with the stem 36 of an auxiliary spring-pressed centrifugal mass 35. When the driving-ring 21 is retarded, as by the throttling of the engine when the clutch is used in constantmesh with variable-speed gearing, the lugs 29 move back to free the key. which is thrown out by centrifugal force, the spring 17, and, the overrunning of the shaft 10. Fig. 5 shows a modification, in which the disc is replaced by a housing 14a supported by arcuate lugs 38 sliding in slots 39 in side plates 40 bolted to the toothed ring 21, which carries the lever 24, the compensating- mechanism 35 &c. not being shown. The Provisional Specification describes a magneticallyactuated pivoted detent for latching the key in its outer position, and states that the shaft may be the driving or driven member.