Fig. 96. Muffler.
Almost any design of muffler is serviceable, if it has sufficient area. However large it may be it is always advisable to have a valve in the pipe A from the engine manifold, so the muffler can be cut out going up steep hills.
Ball and Roller Bearings.—All running gears are provided with either ball, or roller bearings. For heavy vehicles roller bearings are most serviceable, but for light vehicles and for speed most manufacturers prefer ball-bearings.
Race Ways.—The object in the use of balls, is to provide two, three, or four points of contact, which should be so arranged as to have the paths of the bearings of equal lengths, as nearly as possible, and thus prevent the balls from wearing by creeping along the contact walls, and also thereby wearing the paths on which they travel.
Fig. 97. 3-Point Roller Bearing.
The Three-Point Contact.—To understand the full importance of this, examine Fig. 97, in which A is the roller, or shaft, and B the hub having the raceway C designed to hold the balls D, and gives two points of contact, the third point being the shaft A.
Fig. 98. Wrong Bearing.