Page:Motors and motor-driving (1902).djvu/242

210 small as possible, and when the spring rests upon too long a seat under the strap bolts. All the conditions as to best thickness and number and width of spring leaves are best met by springs of the longer type. They should always be bedded upon the axle, with a piece of leather between them and the axle and between them and the clip bolts holding them on. Whenever possible a hard rubber buffer should be attached to the centre of the spring as a chock-block, to avoid the severe shock to springs when the frame goes down the full range of the springs, as when running over a gutter.

The breakage of a spring leaf most frequently takes place at the centre of the leaf, where the contrary flexure occurs between the two clip bolts. A broken leaf may thus be made to do duty temporarily by clipping it up to the other leaves by means of clips which can be bought for the purpose, and one of which at least should always be carried with the spare parts on a car.

Generally a car suspension consists of four springs all placed longitudinally, one to each wheel, but some cars, such as one or two of the American steam and electric motors, are fitted with cross springs at the back. These are not sufficiently general to make any special reference to them any more necessary than are the springs themselves.

Springs are connected to their hangers at one or both ends by means of a pair of links, which radiate to allow for the bending and straightening of the springs. These links are often much too short for free movement, sometimes not more than inch between the centres of the pivoting bolts. These should never be less than 2 inches, and 3 inches is better, even in voiturettes, and more than 3 inches in the larger cars. Very considerable direct and indirect stresses are visited upon the bolts and nuts by which spring hangers are fastened to the frame, and these should be examined from time to time, although they are fixtures.

It should always be remembered that the breakage of a front spring may not only of itself be the cause of a severe