Patent GB-409251-A (GB)
Title: Improvements in clutches and change-speed mechanisms
IPC: F16D41/066
Filed: 1933-12-18
Abstract: 409,251. Clutches; variable-speed gearing. RICHARDS, C. H., 173, Harvard Avenue, Boston, U.S.A. Dec. 18, 1933, No. 35636. Convention date, March 11. [Class 80 (ii).] A clutch comprises a rotary member positioned coaxially with aligned driving and driven members, and rollers which transmit the opposing driving and resistance torques to the rotary member, such that when the resistance torque exceeds the driving torque the speed of the rotary member is changed whereby driving engagement is disrupted, such engagement being automatically restored when a steady balance between the torques is again established. The rollers 19, Figs. 1 and 2, are located in slots 17 in the cup-shaped driven member B and engage between the inner surface of the cup-shaped driving member A and cam grooves 21 on the rotary member M. Whilst the torques are in balance, the rollers ride up the cam grooves to lock the members A, B, M together, but when the resistance torque exceeds the driving torque by a predetermined amount, determined by the cam angle, the member M is accelerated so that the rollers pass into the free position. A spring 20, the ends of which engage in the members B, M, tends to hold the parts in driving position. The member B can overrun the member A. The application to a motor-vehicle gear box is shown in Fig. 4, in which a lay shaft 65 is driven from the driving shaft 62 through meshing gears 68, 69. A gear 70 loose on the shaft 65 is in mesh with a gear 71 loose on the shaft 62, a gear 73 fixed to the shaft 65 is in mesh with a gear 75 forming the outer element of a free-wheel roller clutch C, the inner element 77 of which is fixed to the gear 71, while a further gear 74 fixed to the shaft 65 is in mesh, through a reversing pinion 67, with a gear 76 loose on the driven shaft 63. A clutch sleeve 80, controlled by a lever 87 and splined on the shaft 63, is adapted to connect the latter either to the gear 76, for reverse drive, or to the element 77, for forward drive. Rotary members M<1> and M<2> and rollers 97 and 107 are associated with the gears 69, 71 and 68, 70 to provide clutches of the character shown in Figs. 1 and 2, the gears 68, 69 corresponding to the member A and the gears 70, 71 to the member B. As shown in Fig. 6, however, spring-pressed shoes 5 engage the rollers so as to prevent excessive spinning thereof, and, to enable the engine to be used as a brake, additional rollers 98 engage additional cam grooves 100 on the member M<1>, these grooves being oppositely arranged with respect to the grooves 99 engaged by the rollers 97. During highspeed drive, the clutch M<1> is operative, the gear 70 overrunning the gear 68 and the element 77 overrunning the gear 75. During intermediatespeed drive, the clutch M<2> is operative, the gear 69 overrunning the gear 71 and the element 77 still overrunning the gear 75. During lowspeed drive, the clutch C is operative, the gear 69 overrunning the gear 71 and the gear 68 overrunning the gear 70. To change up, the throttle is first closed and then slowly reopened. To change down, the throttle is closed and then suddenly reopened, while to change to a still lower gear the engine clutch is disengaged, the throttle being kept open, and then re-engaged. Automatic change-down will, however, occur if the engine stalls, and automatic change-up will occur if the vehicle drives the engine while in other than high gear. Specification 408,234 is referred to.