Drill and tap the eccentric edgeways for a lock screw.
A piece to which the eccentric strap, eccentric rod, and pump rod are
attached is cut out of 5/16-inch brass. Its shape is indicated in Fig. 53.
The side next the eccentric must be shaped as accurately as possible to the
radius of the eccentric. The strap, of strip brass, is fastened to the
piece by four screws, the eccentric rod by two screws.
Crosshead and Guides.--The crosshead (Figs. 53 and 54) is built up by
soldering together a flat foot of steel, a brass upright, and a tubular top
fitting the piston rod. The guides, which consist of a bed, covers, and
distance-pieces united by screws (Fig. 64), have to withstand a lot of
wear, and should preferably be of steel. The importance of having them
quite flat and straight is, of course, obvious.
[Illustration: FIG. 64.--Cross section of crosshead and guide.]
The last 1-3/8 inches of the piston rod has a screw thread cut on it to
engage with a threaded hole in the fork (cut out of thick brass plate), to
which the rear end of the connecting rod is pinned, and to take the lock
nut which presses the crosshead against this fork.
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