-Parts of slide valve.]
The Crank and Crank Shaft.--The next thing to take in hand is the fixing
of the crank shaft. This is a piece of 3/8 or 1/2 inch steel rod 5 inches
long.
The bearings for this may be pieces of brass tubing, fitting the rod fairly
tight. By making them of good length--1 inch--the wear is reduced to almost
nothing if the lubricating can is used as often as it should be.
Each bearing is shown with two standards. The doubling increases rigidity,
and enables an oil cup to be fixed centrally.
The shape of the standards will be gathered from Fig. 53, their outline
being dotted in behind the crank.
Cut out and bend the standards--after drilling the holes for the foot
screws--before measuring off for the centres of the holes; in fact, follow
the course laid down with regard to the cylinder standards.
Make a bold scratch across the bedplate to show where the centre line of
the shaft should be, and another along the bed for the piston-rod centre
line. (Position given on p. 138.)
Bore holes in the bearings for the oil cups, which may be merely forced in
after the engine is complete.
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