Patent GB-821857-A (GB)
Title: Improvements in or relating to variable speed torque transmission arrangements
IPC: F16H29/18
Filed: 1956-06-22
Abstract: 821,857. Variable-speed ratchet gear. WIENAND, M. June 22, 1956 [June 22, 1955], No. 19414/56. Class 80 (2). [Also in Group XXXIV] Relates to variable-ratio ratchet gearing. In Figs. 1, 2, which are explanatory only, a rotating crank-shaft 3 carries freely on its cranked end a disc 1 which frictionally engages a stationary member having a circular aperture 2 of diameter D greater than the diameter d of the disc 1. When the crank-shaft 10 rotates, the disc 1 runs around inside the aperture 2, and turns on the crank-shaft 3 in the opposite direction to that in which the crank-shaft is itself rotating. Universal joint means 4, 5 transmit drive from the disc 1 to a driven shaft 7. In gearing according to the invention, the disc 1 is replaced by a disc 16, Figs. 3, 4, having radial slots 15 receiving pins 12 on one-way detent mechanisms 14 which can rotate in an annular groove in a stationary member 13. A driving shaft 17 has a squared end 18 engaging in a rectangular slot 19 in a driving disc 19a. The driving disc 19a is mounted by ball-bearings to rotate freely within the disc 16. The disc 16 is again connected by universal joint mechanism 20 to a driven shaft 20a. On rotating the driving-shaft 17 and driving disc 19a, the oneway detent mechanisms 14 constrain the disc 16 to rotate in the opposite direction, and thus drive the driven shaft 20a. Variation of the eccentricity between the axis of rotation of the disc 16 and the axis of the shaft 17, by mechanism not shown in Figs. 3, 4, adjusts the ratio of the gearing. In one preferred embodiment of the invention, a driving-shaft 26, Fig. 5, has a squared portion 27 in grooves in which are axially slidable two wedge-shaped keys 28. A driving member 33 having slots for the keys 28 is mounted at the end of the shaft 27, and is connected through a ball-bearing 33a with a transmission disc 34 having radial slots 34a. Guide-pins 35 in the radial slots 34a are each connected at their tops and bottoms to one-way detent mechanisms 37, 38, Fig. 6, which lie in annular grooves 36 in stationary reaction members 36a, 36b. The slotted disc 34 is provided with a diametral ridge 41 engaging a corresponding groove in an intermediate disc 42 connected by a similar groove and slotted means to a driven disc 44 on an output shaft 46. The eccentricity of the driving disc 33 relative to the shaft 27 &c. is adjusted by sliding the keys 28 axially of the shaft 26. Projections 32 at the ends of the keys 28 are engaged by the inner member 30 of a ball-bearing 31, the outer race of which is fast with a sleeve 51 threaded on to a stationary support 52. The outside of the sleeve 51 is toothed as at 53 so that turning a control-shaft 55 drives through the gears shown to screw the sleeve up and down relatively to the shaft 26. The wedge-shaped end 28a of the keys 28 thus adjusts the eccentricity of the driving member 33, and varies the ratio of the gearing. The grooved coupling connection 42 . . . 45 allows drive to be transmitted from the disc 34 to the shaft 46 when these two parts are not concentric with each other. Counterbalance weights 49, 50 are mounted upon the shaft 26 on the keys 28 in such a way that their eccentricity is adjusted simultaneously with adjustment of the eccentricity of the disc 34. In another form of the invention, shown schematically in Fig. 7, the use of mechanism to transmit drive from one member to another member not concentric therewith is avoided. The cranked portion of a driving-shaft 58 carries rotatably a transmission member consisting of two integral discs 56, 57. The disc 56 is formed with radial slots (not shown) containing guide-pins mounted in one-way detent mechanisms sliding round a fixed ring 59. The disc 57 is formed similarly with radial slots &c. (not shown), which connect it to a rotatable driven member 61 fast on a driven shaft 64. Rotation of the driving-shaft 58 thus causes the discs 56, 57 to move in a circle in the direction opposite to the direction of rotation of the driving-shaft, and turns the driven-shaft 64. In a preferred embodiment of this form of the invention, Figs. 8 . . . 11 (not shown), adjustment of the eccentricity of the disc 56 &c. with respect to the axis of the driving and driven shaft 58, 64 to vary the ratio is effected by sliding axially a wedged-shaped member similar to that described with respect to Fig. 5. The gearing is provided with two counter-weights adjusted with respect to the main axis of the gear simultaneously with adjustment of the gear ratio, to balance the eccentric masses of the discs 56 &c.