New Type Of Semi-Automatic Gearbox

Northern Advocate, 12 June 1937, Page 13

New Type Of SemiAutomatic Gearbox

Designed by a French engineer who has made a special study of transmission systems, a new gearbox is announced which provides push-button control of a semi-automatic character as an outstanding feature.

The driver is provided with two buttons, fitted close to the rim of the steering wheel, one of which is coloured black and the other red. When getting away from a standstill., pressure on the red button causes the transmission to change automatically from gear to gear, as the rord speed inci’eases, until the direct drive is reached. The gear in use at any time is indicated by figures which light up at the centre of the facia, these being incorporated in a dial which includes a speedometer and clock. If it be desired to change down, pressure oh the black button will result in a single change to the gear below that which is in use. Thus, When running in top, this button must be operated once to provide third gear and again if second gear be needed. At the end of the scale pressure on the same button provides reverse. Between each successive gear ratio there is a neutral pbsition in which a free wheel comes into action.

Although the mechanism is of the epicydic type,, the arrangement of the gearing is highly unusual. It is claimed that in comparison with ordinary planetary gears the new system enables a much lighter braking system to be used, because the brake elements are eccentric* to the axles and the shafts. It is this feature which enables the push button to be readily incorporated. ' "'■> . , ,

The* gearing is exceedingly compact; the pinion at the centre is connected to the engine arid meshes with teeth cut inside an eccentrically mounted ring. External teeth on the sariie ring engage with internal teeth on a surrounding annulus gear, the annulus is connected to the rear Wheels of the car, arid the intermediate ring is supported by a cage to which a brake can be applied.

When the car is at a standstill with the engine idling', the annulus is stationary, but the central pinion is turning at a low speed. Consequently,! the intermediate gear ring is forced to roll around the iWide of the annulus in a manner reminiscent of the planetary movement of an ordinary epicyclic gear. The orbital motion of the ring and its Cage is in a direction opposite to the rotation of the engine and central pinion. To move the car from a standstill a brake is applied to the cage which carries the intermediate ring, so preventing the ring from rolling round the inside of trie annulus. As- the pinion continues to turn with the engine, the teeth reactions set the annulus in motion, and the car consequently gets away. Under this first speed condition the annulus, intermediate ring, and central pinion all rotate in the same direction, and a suitable gear reduction is obtained.

As in other epicyclic gears, the application of the brake when starting makes the use of a separate clutch unnecessary.