Page 79 - Reciprocating Compressors Operation Maintenance

66 Reciprocating Compressors: Operation and Maintenance

Castellated Piston Rod. The end of the piston rod is machined with
castellations, and a pin or lock dowel is inserted through the crosshead to
prevent rod rotation. This method also uses a nut against the face of the
crosshead for locking, as in Figure 2-27.

Crosshead

Piston Rod

Lock Dowel
FIGURE 2-27. Castellated rod end with locking dowel (Source: Dresser-
Rand, Painted Post, New York).

Set Screw Lock. The crosshead is drilled and tapped for a set screw at
the threads of the piston rod. A copper disc is inserted into the hole to
prevent damage of the rod threads by the set screw. The crosshead nuts
are also locked in a similar manner with the set screws and copper discs
(Figure 2-28).

FIGURE 2-28. Set screw locking approach used on small compressors
(Source: Dresser-Rand, Painted Post, New York).