NEW GEARBOX

Southland Times, Issue 23047, 14 November 1936, Page 19

NEW GEARBOX

British Experts Impressed

The designer of Sir Malcolm Campbell’s famous Blue Bird, Mr Reid Railton, is one of the co-inventors of a new transmission unit that, according to The Motor, London, has impressed British motoring experts. The new transmission gives four forward speeds, and the design is such that a single synchro-mesh unit gives easy engagement for each one. In most synchro-mesh designs, easy engagement is provided for only the one ratio below top gear. Furthermore, these four forward speeds are obtained by using only six constant mesh gears, so that the gearbox is so small and the number of gears embodied reduced to such a low number that the not inconsiderable losses caused by the churning of the lubricant are reduced to quite a large extent.

The secret is in the use of a duplicated clutch, one connected to a normal shaft and the other to a nollow shaft surrounding it. Each shaft through the medium of its own set of constant mesh gears, differing in ratio the one from the other, is capable of driving the normal counter-shaft of the gearbox when locked by the clutch plates to the flywheel of the engine. Thus by different combinations of clutch and gears in mesh, four forward speeds are obtained with a minimum number of parts, and the usual direct drive on top gear is obtained by using the inner clutch shaft which drives direct through the sliding shaft of the gearbox in the ordinary manner.

In actual fact, there is nothing at all new about the design of the gearbox, as it simply is a normal design, but having only two speeds. These two speeds are multiplied by two bv using the duplicated clutch and countershaft constant mesh gears described. However, the operating mechanism has been designed so that pre-selection is possible and a modification can be incorporated to provide for automatic operation of the clutches, and it is because the transmission embodies this very valuable feature of pre-selection with the ruggedness and simplicity of a normal synchro-mesh box, that it is considered that the design is an important contribution to motor engineering An experimental box fitted to a car of medium power was tested thoroughly by a number of British motoring experts, and all were thoroughly impressed by its ease of handling and the possibilities inherent in it. Pre-selec-tion of the gears was secured by a small lever working in a quadrant on the steering column, and depression and release of the clutch pedal was all that was necessary to make the actual change. To secure automatic action of the clutch, the gear lever was depressed slightly before making a change, but, in this case, there was no pre-selection, although the operation could be carried out very rapidly.