Frames out of Line.

The spare engine was gotten together and put into service. A new crosshead was procured by a nearby foundry, and when it was put in the precaution was taken to key the rod up snugly on the crank-pin and drop the other end down on to the crosshead pin. It fitted squarely. The rod was then disconnected from the crank-pin, and keyed up on to the crosshead, and then dropped down onto the crank-pin, and that came square. The engine was then started up, and it ran perfectly quiet.

The old crosshead was so badly broken that just what the trouble was could not be determined, but the probability is that the pin was put in something as shown in Fig. 45, though not so crooked.

Had the trial of the connecting rod been made with the first pin in the same manner that it was with the second, the trouble would have been discovered at the outset. When setting up engines it is a good plan to try the connecting rod, as described.

Another error that has been found many times is shown in Fig. 46. A line put through the engine will show that the cylinder is not in line with the guides and will have to be thrown around by putting in shims at either O or E.

Twisted Guides.

A not infrequent defect is shown in Fig. 47, and can be detected by placing a plumb, as shown. This is particularly bad with V-guides. In one factory I have in mind there are four engines from the same builder with V-guides that stand in this manner. Fortunately, the

engines run forward and do not make as much trouble as the running backward.

The only remedy is to trim down the shoes at A and A' until the crossheads stand plumb.

There is no excuse for a V-guide. There have been cases where the foundation under a cylinder has settled

Crank Pin not Central.

more under one side than the other and twisted the guides.

Pounding from this cause is a compound noise, and while it takes place on the center the pound will be at

the crosshead and crank-pin both, but not exactly the same time.

Another trouble that sometimes occurs is that the center line through the engine does not come through center of pin, as shown in Fig. 48, where the center of

Cranks out of Square.

pin is the line A, while the line through engine is at B.

The remedy for this is to trim down one side of the brasses and add on to the other side, as shown in Fig. 48. When they have to be cut off on the side toward the crank and the rod is round, care must be taken that the

large part of the rod does not get too close to the crank disk when the crank-pin is at the forward center. If the crosshead is one-sided, the same course may be pursued. To determine if the shaft is level, suspend a plumb line, as in Fig. 49. If it is out, as shown, the pound will

Pistons too Small.

not be on the center, but when the crank-pin is nearly half way between. The only remedy is to make the shaft level and with a pin put in crooked, as in Fig. 50, a new pin put in straight will be necessary.

Should a piston be too small, as shown in Fig. 51, and a larger force of the steam strike it on one side, the piston will be forced to the other side and there will be

a severe pound. When the cylinder head is taken off, nothing out of the way can be seen. The remedy is a piston with a broader bearing at the bottom.

A cylinder having shoulders will pound. A Corliss or similar valve having end play may pound if the steam impinges just right to force it endwise. The valve will wear smoother if it has end play, and unless the pound is too great it will be better to leave it. It can be eased