Patent GB-532752-A (GB)
Title: Variable speed gearing
IPC: F16H47/04
Filed: 1939-08-30
Abstract: 532,752. Variable-speed gearing. PARAVICINI, T. P. DE. Aug. 30, 1939, No. 24929. [Class 80 (ii)] [Also in Group XXVI] In variable-speed gearing, particularly for motor vehicles or aircraft, comprising a primary, differential, epicyclic train having four or more members rotating about the same axis, two or more of the reaction members are operatively coupled through a secondary changes p e e d mechanism which is mounted in a stationary casing. Most of the power is transmitted through the primary train, and since the secondary train transmits very small power, it can consist of a small change-speed box of the toothed - gear, friction, hydraulic, or electrical type. In the gearing shown in Fig. 1, a sun-wheel b' on the driving-shaft a engages planet-wheels c<1> which are mounted on a cage g' and engage an annulus h<1>. Wheels d', integral with the wheels c<1>, engage a sun wheel e<1> on a shaft f carrying planet-wheels c<2> which engage an annulus h' on the driven-shaft o, and a sun-wheel b<2>. Wheels d<2>, integral with the wheels c<2>, engage a sunwheel e<2>, and an annulus m provided with a brake n which is applied to reverse the drive. The gearing includes infinitely-variable changespeed devices G\ G<2> each consisting, as shown in Fig. 3, of two variable-capacity pumps or motors X<1>, X<2> connected by pipes Y', Y<2> and each consisting of a rotor D provided with sliding vanes working in an adjustable track S. The rotors of the device G' are provided with gears k<1>, l<1> which engage gears i<1>, j<1> on the cage g' and annulus h'. Similarly, the rotors of the device G<2> are provided with pinions k<2>, l<2> which engage gears i<2>, j<2> connected to the sun-wheels b<2>, e<2>. If torque is applied to the pinion k<1>, the pump X<1> of the device G' drives the motor X<2> and power is transmitted to the gear l<1>. Similarly, torque applied to the gears l<1>, l<2>, k<2> can be transmitted to the gears k<1>, k<2>, l<2> respectively. The gear k' and consequently the cage g' can be locked by adjusting the pumps X\ X<2> to the maximum and zero displacement positions respectively. Similarly, the gears l<1>, l<2>, k<2> and the associated members of the epicyclic trains can be locked by adjusting the associated pumps. By varying the displacements of the pumps, the gear-ratio of the epicyclic trains is progressively and smoothly adjusted. The device G' operates during both forward and reverse drive, whilst the device G<2> operates only during forward motion. In an alternative construction, Fig. 2, the cage i and annulus f engage gears k, l which are coupled by a secondary four-speed gear. The gear comprises an annulus h' secured to the shaft f' of the gear k and co-operating with stepped planetpinions c<3>, d<3> which engage a sun-wheel e<3> on the shaft f<2> of the gear l, and a sun-wheel e<4>. Brakes m<1>, m<2>, m' co-operate with planet-cage g<3>, the sun-wheels e<4> and the shaft f<2>. The shaft f<1> and the brakes m<1>, m<2> have free-wheels p<1>, p<2>, p<3> permitting rotation in the opposite direction to the driving-shaft a, and the shaft f<2> has a freewheel p<4> permitting rotation in the same direction. For top gear all the brakes are locked, and the brakes m<3>, m<2>, m<1> are released successively to step-down the gear. For a top-speed .gear the epicycle train e' ... h<3> is omitted.