GB330929A - Improvements in or relating to toothed gearing - Google Patents

Abstract

330,929. Crowsley, P. S. Dec. 20, 1928. Variable-speed epicyclic gearing; clutches, ratchet.-In epicyclic speedgearing, the planet-carrier carries frictional means for connecting it either to a stationary member for geared drive or to the driving or driven member for solid drive. A wheel d, Fig. 1, secured to the driving-shaft e engages an eccentric wheel c<1> connected by an Oldham coupling to a disc b on the driven shaft a and carried loosely in a carrier g which can be connected either to a flange q<1> on the casing for low speed or to the disc b for solid drive by a clutch device shown in Fig. 3. Friction clutch pawls h<3> turn on pivots h<50> in the carrier g and engage the periphery of the disc b under the pressure of spring-pressed plungers h<6x>. The pawls are normally forced to disengaged position by springs h<4> connected to weighted arms h of levers with toes h<1> engaging the pawl ends, but upon rise of speed of the carrier g, centrifugal force lifts the weighted arms and the pawls are released for engagement. Similar brake pawls h<6> are spring .pressed to engage the stationary flange q<1>, but are moved to disengaged position by the centrifugal action of the arms h. The shaft a is thus normally driven at reduced speed, increase of speed of the driving-shaft not affecting the arms h on the stationary carrier g. When solid drive is required, the shaft e is slowed, when reaction upon the planet carrier g causes it to rotate in reverse direction, the pawls h<6> being released by this action, centrifugal action of the arms h then releasing the pawls h<3> for jamming engagement with the disc b, whereupon a solid forward drive is instituted. To change from solid to reduced drive, the shaft e is again slowed, when the reversal of driving-effort and the reduction of centrifugal affect on the arms h. allows the pawls h<6> to re-engage the flange q<1> and causes the pawls h<3> to disengage from the disc b; the shaft e can then be speeded up. In a modification, a driving-wheel engages an eccentric internal wheel which is loose in the carrier and is secured rigidly or by an Oldham coupling to a second external wheel gearing with a second internal wheel secured to the driven shaft. Fig 5 shows a duplicated form of this device. The driving-shaft a<2> carries a pinion n gearing with an eccentric wheel n' loose in a carrier s and secured to a wheel n<2> gearing with an internal wheel n<3> on a second shaft n<4> similarly geared to the driven shaft r. By positively-operated friction means comprising clutch pawls u<2> and brake pawls u<3>, the carrier s may be connected to the driving- shaft a<2> on the stationary flange t, so that its gear drives solid or through the toothed wheels. The gear in the second carrier s<1> may be similarly controlled, so giving four alternative speeds under the control of cones v, v' and a sliding rod x which may be controlled by hand or by a centrifugal governor x<3> driven by a wheel x<5> gearing with the final wheel o<4> of the main gearing. A reverse drive may be obtained by sliding the gear o<4> into mesh with a wheel y driven by chain &c. gearing from the driving-shaft a<2> According to the Provisional Specification, a centrifugal brake comprising a ring pivoted on the carrier on an axis at right-angles to the main axis or brake bands or blocks controlled by levers and engaging the periphery or sides of the carrier, may be employed.