Finding Locomotive Dead Centers
Page 2 of 5
By Jeffrey G. Hook
(Scroll down for all illustrations. Captions above illustrations.)
Fig. 3. - Using a hermaphrodite caliper arc (C) is scribed on the rim of the main driving wheel at a constant distance from the tread and intersecting arcs (A) and (B). Center punch marks (A) and (B) are then made at the two intersections.
Fig. 4. - A divider is adjusted until, with the same setting, it will produce arc (AA) from center punch mark (A) and arc (BB) from center punch mark (B) that intersect each other at the same point on arc (C). Center punch mark (C) is made at the intersection of the three arcs and represents the dead center. Care must be taken to label center punch mark (C) in order to prevent future confusion as to which center punch mark represents the dead center.
Fig. 5. - In order to place the engine on the front dead center the long pointed end of the wheel tram is placed in center punch mark (F) and the main driving wheel is carefully turned until the bent pointed end of the wheel tram will enter center punch mark (C).
To find the opposite dead center the same procedure is used except the dial indicator is mounted so as to contact the opposite end of the crosshead.
