Page:Steamlocomotivec00ahrorich.djvu/80

 Wheel Balancing. In some shops the wheels when finished are balanced by revolving them at high speed in a special machine, and adding small weights until they revolve with perfect steadiness. A machine for this purpose designed by Mr. G. J. Churchward, chief mechanical engineer of the, and used at , is illustrated in Fig. 35. The wheels and axle rest in bearings supported by springs, and are driven at a speed corresponding to 60 m.p.h. by means of a 55 h.p. electric motor. The speed is registered by the counter on the wall at the back of the machine. The hand wheel actuates the brake blocks by means of a screw, so that the wheels can be stopped quickly when required after the current has been cut off. The excess or deficiency of balance, as found by the small weights attached during the test to secure steady running, is afterwards rectified in the balance weights.