332,302. Thomson, B. April 25, 1929. Clutches, friction and claw; variable-speed toothed gearing.- In claw clutches of the kind in which the members are released for engagement in either direction of rotation only when an intermediate element is transmitting no accelerative or declerative torque, this element positively engages one claw-clutch member and frictionally engages the other at a greater radius than either its positive engagement or the clutch claws themselves. The clutch is applicable to variable-speed gearing, to coupling the shafts of propellers working in elastic and non-elastic fluids, and to driving workshop machines. In one form, a member 2, Fig. 2, slidable on the driving shaft (not shown), has a coned flange 4 and dogs 6 with pointed ends formed by helical surfaces 7, and a member 10, Fig. 4, fast on the driven shaft 9 has teeth 11 with similar pointed ends 12. The intermediate element 13, Fig. 3, revoluble on the driving shaft, has a coacting coned flange 17 and apertures 19, the narrow parts 20 of which are sliding fits on the teeth 11, while the wide parts 21 terminate in helical surfaces 22. On sliding the member 2 to the right, the cones 4, 17 engage and carry the surfaces 22 on one or other side of the apertures 19 into contact with the corresponding surfaces 12. The mean radius and angle of the cones and the pitch of the helical surfaces are so calculated that, when the clutch is not under working load, the resultant thrust on the surfaces 22, 12 lies within the angle of friction, while the cones 4, 17 are transmitting accelerative or decelerative torque, but as soon as the members 2, 10 are synchronized, the thrust becomes nearly axial, causing the parts 10, 13 to turn relatively and the teeth 6, 11 to engage. When the member 2 is withdrawn, the part 13 is returned up to a shoulder, such as the ends of the driving-shaft splines, by a spring or lost-motion connection with the member 2, the cones 4, 17 being then slightly separated. The helical faces on the parts 10, 13 may be formed on one part only or may be replaced by inclined planes or by coned pegs coacting with sloping surfaces in cylindrical or elongated holes. In a modification, Fig. 8 (not shown), the clutch comprises a slidable gear-wheel having a conical flange and pointed dogs in its bore, a shaft having coacting pointed dogs, and an intermediate element comprising a sleeve-portion, lying inside the dogs on the wheel bore, and a flange with a coned periphery, the flange having facial pointed teeth to coact with the shaft dogs and, between them, apertures in line with axial slots in the sleeveportion, through which the shaft dogs can pass on synchronization. Fig. 9 shows a further modification, in which a pinion 25, having pointed facial dogs 26, is revoluble on a shaft 39 provided with shouldered splines 49, on which slides a clutch member 53 with corresponding pointed dogs 54. A cone 57, screwed on the member 53, coacts with a cone 63 on the intermediate element 62, which has apertures 64, similar to the apertures 19, Fig. 3, and is withdrawn against the spline shoulders 50 by contact of a piston-ring 60 in the sliding member 53 with a lip 61. The wheel 25 is located between the spline shoulders 51 and a washer 52<a> abutting against a bearing 52. In another form, Fig. 10 (not shown), one member, having pointed teeth and a bolted-on male cone, is splined to the driven shaft, and the inter- .mediate element is loose on a reduced part of the shaft and spring-pressed against the shaft shoulder, the female cone thereon being then free of the male cone. A member integral with the driving shaft has pointed teeth, which remain in contact with chamfered openings in the intermediate element even when the sliding-member is fully withdrawn. Fig. 11 shows a form suitable for Diesel locomotive and other heavy gearing. The sliding-member 85, splined to a shaft 86, abuts against a ring 87 and has pointed dogs 89 coacting with like dogs 90 on the loose wheel 92. The intermediate element 95, coacting with the wheel 92 by a multiple-plate clutch 94, has teeth 96 with apertures between somewhat as shown in Fig. 3, and is pressed by a volute spring 98. The clutch 94 is opened on full withdrawal of the member 85 by shoulders 97, 99. In the variable-speed gear shown in Fig. 13, first speed or reverse are respectively obtained by sliding a spur pinion 143 or the constant-mesh pair 144, 144<a> along the lay-shaft 138 into engagement with the wheel 114 on the driven shaft 111. Top and second speeds are transmitted respectively through a direct-drive dog clutch 108, 118 and the helical wheels 107, 137, 141, 127 and dog clutch 126, 125. The clutch-members 118, 125 are formed on the wheel 114, slidable on splines 113, reduced parts 119, 131 of which form shoulders for the spring-pressed intermediate elements 117, 132, provided as before with friction cones and chamfered apertures. The synchronizing-clutch arrangement may be used for all or one only of the forward speeds, which may be other than three in number. Fig. 14 shows a clutch for Diesel locomotives &c., in which the intermediate element 156 - - 160 is positively connected to the sliding-member 150 by means other than the clutch dogs 167, which coact with dogs 168 on the. loose wheel 152. The intermediate element is pressed against a shoulder 170 by a spring 169, which yields when the cones 154, 156 contact, and coacts by teeth 161 with the bevelled faces 165 of slots 163 in the part 150. In some forms, the intermediate element may wholly surround one clutch-member and engage it by radial projections and recesses. The Provisional Specifications describe constructions differing mainly in small details. In particular, the second Provisional Specification states that the clutch may be unidirectional or bidirectional, and describes a form of variable-speed gear resembling that described in the complete Specification, but in which the intermediate-members are withdrawn by the engagement of rings like piston-rings with the overhanging end-walls of recesses in the gearwheels, and the clutch-member 125 is slidable on the reduced shaft part 131. The invention may be applied also to multiplying as well as reduction gearing.