Young Engineer's Guide

by J. V. Rohan

The Cross-head is of cast iron and connects the piston rod to the connecting rod, and is that part of an engine where the motion is changed from vibrating to rotary. The piston rod is fastened securely to it, while the connecting rod is attached by wrist-pin. On a V guide or bored guide engine frame the cross-head is supplied with adjustable shoe slides that can be adjusted to take up their wear and fit the guides properly, also to keep the piston rod in line. On a bar or locomotive guide engine the cross-head is adjusted by removing the liners from between the bars.

ENGINE FRAME.

The Engine Frame is the large casting which contains the bored, V shaped or locomotive guides for cross-head shoes. It also contains the pillow block for crank shaft at one end and the cylinder is bolted to the other. They are made in many different styles and shapes, but all answer the same purpose.

CONNECTING ROD.

The Connecting Rod on an engine is the connection between the cross-head and crank-pin; it is generally made of wrought iron or steel, with brass boxes at each end held in position by wrought straps. These straps are attached to the connecting rod by gibs and keys. Connecting rods are sometimes made with mortised ends to receive the brass boxes, which are held in place by wedge block and adjusting screw. The latter style is used principally on the larger makes of engines. While the connecting rod with mortised ends are considered a little the safest, the straps on the ends of rods are most commonly used. The brass boxes at ends of connecting rod are adjustable to take up the wear by use of the gibs and keys, and they should be adjusted as frequently as there is any lost motion discovered at the crank-pin or cross-head, which will be indicated by a knocking or pounding as the crank passes over the centers.

Connecting Rod.

CRANK.

The Crank is that part of an engine by which the effect of the steam acting against the piston is converted into work. There are two kinds, Side and Center crank. The term Side crank refers to a disc plate or a crank attached to one end of a shaft and in which is placed the crank-pin. When the shaft extends to the right the engine is called a right hand engine, and when it extends to the left it is called a left hand engine.

The term Center crank refers to a shaft with the crank in the center, the shaft extending equally both ways and so constructed as to be very well balanced. It is optional as to which gives the best results as both kinds are used upon all sizes of engines.