Page:Motors and motor-driving (1902).djvu/227

Rh gear with the transmission gear proper; and the best way to do this perhaps will be to illustrate the principles employed by reference to examples of the various systems.

In the first place, belt-driving cars have usually two belts running on pulleys of different sizes, so that shifting the belts causes either one or the other of the two speed ratios to be used. The belt system generally drives the car through chains, so that whilst belt gearing is used for the speed variation, the transmission to the wheels is by chains.

In using belts care must be taken in shifting the belts to throw off one before attempting to put the other into operation, or broken belts and perhaps worse accidents may result. Belt driving is wonderfully smooth and quiet in action, and commendable from this point, but unless very carefully looked after liable to give trouble by undue slipping and breaking. When carefully attended to and intelligently applied, belts can be made very satisfactory. Mr. Lyons Sampson, for instance, tells me he has had one pair of belts in use for over a year, and has had no trouble with them. But then Mr. Sampson has given the subject very careful consideration, and sees that they get the little care they need. For instance, he runs his belts flat instead of crossed, which by not bending them so much puts less strain on the fibres. He uses the belt, too, with the skin side to the pulleys, protects them as much as possible from wet, and uses loose pulleys of the same diameter as the fast ones instead of slightly smaller, as is usual. This, whilst keeping the strain on during use, does not necessitate the belt being pushed up over the sharp edge of the fast pulley every time it is put into action. Mr. Sampson is also careful to take the belts off entirely when the car is not in use, and so relieve them of strain.

Mr. R. W. Buttemer, another successful belt-user, recommends using lightly tanned leather for the belts instead of raw hide, which is preferred by some, and before putting on a new belt hangs a 1-cwt. weight on it for a day or two to take the stretch out of it, following this by a soaking in castor oil,