Locomotive Engine Running and Management

by Angus Sinclair

ACCURACY ESSENTIAL IN LOCATING THE DEAD CENTER POINTS.

Before proceeding to set the valves, a machinist can not be too careful in locating the exact dead centers. Some men conclude, because there is little motion to the cross-head close to the end of the stroke, that a slight movement of the wheel to one side or the other is of little consequence, and makes no perceptible difference in the relative positions of piston and valve. This is a serious mistake; for, although the piston is moving slowly, the eccentric is proceeding at its ordinary speed, and the valve is moving fast. The loose, quick methods of finding dead centers followed occasionally are not conducive to exactness, and nothing but accuracy is permissible in valve-setting.