Patent GB-798850-A (GB)
Title: Improvements relating to clutches for transmitting rotary motion
IPC: F16D23/10
Filed: 1954-08-20
Abstract: 798,850. Free-wheel clutches. SINCLAIR, H. Aug. 10, 1955 [Aug. 20, 1954; Aug. 30, 1954; Jan. 31, 1955], Nos. 24373/54, 25171/54 and 2880/55. Class 80 (2). A clutch of the Leggetype, comprising a toothed clutch member engageable by an intermediate toothed member helically splined on a second clutch member, is provided with a relatively light auxiliary member biased by spring means to initiate the engagement of the toothed clutch member at the moment of synchronism. In one form, a shaft 3, Fg. 1, is helically splined and carries an intermediate member 4 having clutch teeth 5 which can be engaged with teeth 2 on a coaxial surrounding clutch member 1. Axial splines on the intermediate clutch member 4 carry a relatively light ring 9 provided with teeth 10 biased towards the clutch teeth 2 by a spring 11. The intermediate clutch member 4 is biased to the engaged position by a spring 6. In the overrunning condition, the teeth 10, which may be formed with chamfered engaging surfaces, slide smoothly over the teeth 2 on the member 1. When synchronism is reached between the members 1 and 3, and the direction of relative rotation tends to reverse, the ring 9 is moved by the spring 11 so that its teeth 10 engage the teeth 2. Thereupon the intermediate member 4 is screwed along the helical splines of the shaft 3 to bring its external teeth 5 into full engagement with the internal teeth 2 on the member 1. In a modification, Figs. 3, 4 (not shown), the light ring 9 is supported for axial movement by projections engaging between the teeth 5 on the intermediate member 4. In another modification, the teeth 10 are replaced by teeth 16, Fig. 5, formed in a light-weight spring steel ring 15. The teeth 16 are sprung slightly outwards in the axial direction so that they have nuzzling engagement with the clutch teeth 5 when the clutch is disengaged, and may be slightly skewed or raked. In a similar modification, Fig. 6 (not shown), a light-weight spring steel ring provided with teeth sprung slightly axially in direction is secured to the intermediate clutch member 4. In another modification, a light-weight ring 25, Fig. 7, is helically splined on the end of the intermediate clutch member 4, and is biased to the left by a spring 27 to engage its teeth 26 with the teeth 2 on the clutch member 1. On synchronism, the teeth 26 engage with the teeth 2, the ring 25 is screwed along the member 4 until its teeth are in full engagement with the teeth 2, and the intermediate clutch member 4 is then screwed along the shaft 3 to engage its teeth 5 with the clutch teeth 2. In a further modification, similar to that of Fig. 7, an oil retaining casing 32, Fig. 8, is secured to a shaft 33 carrying the clutch member 1, and is fed with oil through a shaft duct 34. On rotation of the shaft 33, oil in the casing takes up the position shown. The ring of oil exerts a tangential drag force upon the light-weight clutch ring 25 and opposes the bias of the spring 27, to reduce the light nuzzling contact between the clutch teeth 2 and teeth 26, when there is relative rotation between them. The drag force decreases as the speed of relative rotation falls to zero when synchronism is reached, and the spring 27 is then fully effective in initiating engagement between the clutch teeth 26 and the clutch teeth 2.