EASY CHANGING

Rotorua Morning Post, Volume 1, Issue 134, 29 January 1932, Page 7

EASY CHANGING

A SIMPLE DEVlCE. Engineers for the past few years have heen concentrating much study on methods hy which the conventional gearbox — a makeshift in the first instance, and never regarded as a satisfaetory solution pf the part it has to .play in the transmission system^ — can be superseded. Some excellent devices have heen iritrddU'Ced, but for the most part they are c'omplicated and costly, and none has come in'to general use except what is known as the silent third or twin high box, which; while it has prdvided two running gedrs with an easily effected change, has not got over the initial difficulty of the change up and change down in tfie lower range. Inventors have cbns'eqU'ently b'eon inclined to desert the conventional type of box altogether. That there is no need to do so seems tb be pr o'ved by a new and sibapl'e device deVeloped in Britain and protected there and in the States. It cdnsists ili employing two very thin gear wheels mounted against the face of the lay-shaft gear and cut with teeth of similar sjiape and pitch. The'se two thih wheels are lightly pressed against a ring of frictioh fabrie; and pegs secured to one of them pass through slots cut in the other. The result is ihat the teeth of the two thih gears are allowed a small amount of relative movement, such that they may either coincide or may move to the extent of about half a pitch, the teeth of the first small wheel then co'ming opposite the gaps in the other. This other is in frictional contact with the lay-shaft gear, and the arrangehient is such that when the gear change is being made only a very short time elapses before the speeds of the parts synchronise and the sliding gear can slip through into engagement. Double declutching is unnecessary in making downward changes, hut in practiee it has heen found desirable to'increase Ihe speed of the engine to effect a rapid and smooth change.