GB625318A - Improvements in friction clutches and in gears embodying them - Google Patents

Abstract

625,318. Change-speed epicyclic gearing. CLERK, R. C. Sept. 3, 1946, No. 29174/47. Divided out of 625,277. [Class 8d (ii)] In a change-speed gear having at least two threeelement planetary gear trains controlled by an electromagnetically-operated friction clutch and at least two electromagnetically-operated friction brakes, one of the brakes, which compounds the trains to bring in the lowest gear ratio, is of the torque-assisted type. As shown, applied to a four speed and reverse gearing, a primary train A having its annulus A8 and planet carrier A6 connected to the driving and driven shafts 10, 11 respectively has a reaction sun A5 carrying the armature 15 of a combined electromagnetic clutch and brake, the clutch coil 12 of which is secured to the annulus A8 and 20 gives a direct drive through the gearing on engagement. Disengagement of the clutch and stationing of the armature 15 by the co-acting brake 3 gives third speed. For second, first and reverse speeds both the clutch 12 and brake 3 are released and the primary train A is cummulatively compounded, by the alternative operation of electromagnetic brakes 2, 1, R, with further gear trains B, C, D of mutually equal gear sizes and having, as far as possible, standardized interchangeable elements. The trains B, C have annuli B8, C8 connected to the driven shaft 11, planet carriers B6, C6 secured to the armatures 16, 18 of brakes 2, 1, and suns B5, C5 rotatable with the sun A5 and carrier B6 respectively, whilst the train D has an annulus D8 secured to the armature 21 of the brake R, a planet carrier D6 connected to the driven shaft 11, and a sun D5 rotatable with the armature 18. The brakes R. 1 are of the torqueassisted type described in the Provisional Specification and in Specification 625,277, and the brakes 1, 2, 3 and clutch 12 are of the kind described in Specification 599,462 having auxiliary synchronizing magnets 1S ... 4S. In the event of electrical failure, an emergency mechanical third speed may be engaged by screwing a bolt 40 through the gear casing to engage a peripheral notch in the armature 15. The clutch coil 12 is energised through a slip ring 13 and carries a vaned rotor 23 which picks up oil from the casing floor and delivers it through a gallery (not shown) to a duct 26 lubricating the trains through bores 28 ... 34 in the shafts 10 and 11. In Fig. 2 (not shown) an overdrive is added by interchanging the driving connections of the primary train and introducing an additional train between it and the secondary train having a sun connected to that of the primary, a planet carrier on the driven shaft and a brakeable annulus secured to the sun of the secondary train. In Fig. 3 (not shown) this arrangement is converted to a fourspeed gear by omitting the first speed train. Specification 597,563, [Group XXXII], also is referred to in the Provisional Specification.