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MODERN STEAM PRACTICE.
holding-down bolts which pass down through the foundation. At
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the other end of the crank shaft a plate is let into the side wall, aproper arch being formed in the wall for its reception.
The crank shaft and crankare of wrought iron, the latterbeing bored in the main eye,somewhat smaller than thepart of the shaft where it isshrunk on. The crank isslightly heated for that pur-pose, it is then slipped on theshaft, and cold water pouredover it, thus shrinking ittightly on. The shaft shouldbe only a very little more indiameter than the eye, aswhen too much is allowed itis apt to strain the materialand weaken the eye. Thecrank and shaft should havea keyway cut prior to theOperation of shrinking on, and when it is cleaned out quite smooth
Fig. 170.—Main Crank.
A, Crank. b, Crank pin rivetted in.