Page:Motors and motor-driving (1902).djvu/234

202 when moved by a hand lever at the side of the car, which is connected up with the slide collar (fig. 17). Thus all three gear wheels revolve at the same speed as the engine. Immediately above this shaft, as shown in fig. 17, is a second shaft arranged parallel to it. This carries upon it the four gear wheels and  all of which are fixed to it and revolve with, but do not slide upon it. This second shaft and its attached gear wheels are contained in the same metal gearcase in which the other gear wheels are enclosed, and which can be filled with lubricating oil. It runs in bearings in the walls of the case, through which it projects at either end. The rear end carries a drum, around which a band brake is applied, and the forward end carries a bevelled pinion , which gears with and drives a bevel wheel.

This wheel is attached to the differential or 'balance gear' (fig. 16) connecting the two halves of a cross countershaft, which runs in long bearings , forming a cross support to the frame. The ends of the cross shaft are furnished with chain sprockets, each carrying a chain which connects with and drives one of the driving wheels through the medium of a chain wheel , which is bolted to the spokes by the bolts. Any stretch in the chains may be taken up by turning the nuts on the radius rods, the purpose of which is to maintain and adjust the proper distance between the countershaft and the wheel axles, and so secure the proper tension on the chains. In making this adjustment, care should be taken to see that the two rods are adjusted equally, or the chain wheels and sprockets will be thrown out of line and the chains may come off or break, besides putting much strain on the bearings and causing considerable additional friction. By putting on different-sized sprockets on the ends of the countershaft the ratio between the revolutions of engine and road wheels, so far as the top speed is concerned, may be varied to suit requirements, and by shifting the gear wheels, and  so that they engage with either  or  this speed may be maintained or reductions made from it. Thus it will be seen that the different-sized