AUTOMATIC GEARS.

Shannon News, 9 October 1928, Page 2

AUTOMATIC GEARS.

MOTORING IS MADE EASY. BRITISH INVENTION. (Published in the "Daily Mail"). LONDON, October 1. The "Daily Mail" reveals that tin 1 biggest secret in the forthcoming motor show at the Olympia will be the Arm-strong-Sicldeley'firm's showing of th'.vvv 20 horse-power models embodying self-changing gears, which have been successfully tested over 50,000 miles. A small pedal replaces the clutch pedal, and a quadrant carries a pointer. The driver moves the pointer lo the desired gear nosition and depresses the clutch." The' change is made instantly, silentlv, and automatically. The'"Daily Mail" says that though gear simplification lia-3 often been introduced, it is the first time that a leading British firm has adopted automatic changes. It may safely be regarded as a first-rate development. The drivei- does not change gear. He chooses the one wanted, and the car does the rest. The gear lever is abolished; the steeling wheel carries a quadrant, upon which six positions_ are marked —reverse, neutral, low, medium, normal, and fast, the four last corresponding to ordinary four forward speeds. A small pedal repines the clutch, penal and the quadrant carries a pointer. The driver moves the pointer to the desired gear nositiou and depresses the clutch. The change is made instantly, silently, and automatically. Each change up involves mere I}' 1 }' the moving of the pointer and the depressing of thc.pedsd. The chf.nges down are equally automatic, i:i tantaneous, and silent.' Indirect gear noise is abol ished, and only the hum of the engine indicates to the- outsider the gear on which the car is running. The silence is due to. a constant mesh gear instead of the sliding type.

The "Daily "Mail's" motoring correspondent tried out the now car, and says that its simplicity is at first baffling, especially in the absence of the "•car (lever. The intermediate gears between low and fast, and vice versa, can be passed over. He tried a direct cliange-dcwn- from fast- to low, doing -10 mTles an hour, and it was quite- sue cessful; but the gcaibox demurred to the high revolutions. He also did 15 changes in 10 seconds, one great advantage being the maintenance of acceleration, because the changes wero instantaneous. Of two cars, matched and similar, except that one had ordinaiy gears and the other self-changing, the former took 50 per cent, longer to reach 40 miles an hour. The latter covered three times the distance, compared with the other, in 25 seconds from a standing £ HOW THE AUTOMATIC GEAR WORKS. *> Judging by its method of operation, this device 'is probably the HumfreySandberg gear box or one very much like it.

The principle is one of constant mesh gears in which all the gears on the main shaft and the lay shaft run constantly in mesh, the selection being carried o'ut by a system of internal clutches.

The driving member positively grips and turns the driven member while power is being, transmitted; but when the car over-runs the engine it freewheels.

Operating mechanism, consists of a series of cams, provided with slots for the reception of the selector levers. The cams are eourded with the clutch pedal, and then with the selector lever, which is at the top of the .steering column. If, when eluT.bing a hill, the driver considers lie will have to change down before he reaches the top, he merely moves his selector lever into the second gear position'. Nothing happens and the car continues in top gear until the waning speed warns that it i; time to change'.. Then the clutch is disengaged, and re-engaged, and the car is in second gear. The selector can be moved into any gear, but the gear being used cannot be changed until the clutch is disengaged, the clutch being the mast?r of the selection cams.