Journal of the Association of Engineering Societies, Vol. 5 : Boston, St. Louis, Chicago, Cleveland, Minneapolis, St. Paul (Classic Reprint)

Excerpt from Journal of the Association of Engineering Societies, Vol. 5: Boston, St. Louis, Chicago, Cleveland, Minneapolis, St. Paul

Some knowledge of the immense size the marine engine has reached may be obtained from the fact that an engine built in England a short time ago had a steam cylinder for reversing thirty-two inches in diame ter. It is by means of these improvements only that engines of ten and t welve thousand horse-power can be controlled The largest com pound on the lakes at the present time is 35 inches high and 70 inches low-pressure cylinder by 48 inches stroke and one as small as 8 inches high and 14 inches low-pressure cylinders by 12-inch stroke, and works as com plete as the larger engines. Vt'hen comparing engines of the lake marine with those built by English and Scotch builders and those on the coast, a vast difference is found in the weight and strength of engines of the same size. Those on the lakes are much the lighter - in fact, they are built. On the banjo principle. While the others are built on the anvil principle one is strong and massive, while the other is light and graceful, but. Begins to spring when heavy work is thrown on it. Some builders lay claims to making the working parts of their engines of steel to reduce the weight. This is a mistake. Stiffness is of more importance. If the crank shaft springs and heats, it is little satisfaction to know that it is. Made of steel. A piston or connecting-rod that trembles is a continual source of annoyance, and any amount of assurance that they are of steel will not satisfy the engineer that they are safe. The engines were orig inally designed to work with 50 and 60 pounds of steam, and at the present time are using a steam pressure of 100 pounds without one. Pound additional weight in the engines. The board of experts on the trial of the United State dispatch boat Dolphin reported that when it was attempted to work the engines to their full power, streams of water had to be run on the journals continually. It does not take very much spring in a shaft 10 inches in diameter with journal 11} diameters long to seriously affect its alignment. And when a power of 500 horse-power is exerted every time the crank passes the centre, there must not be any lack of material at the proper place to keep things from springing. It would seem when an engine showed signs of distress, that there would be danger of something giving way. There is danger, no doubt; but the moment any weakness is discovered by the engineer, every care is taken to favor that particular place. And the engine may run for years without a serious break-down. The banjo principle in some classes of construction is a good one, but nothing short of the anvil principle should be permitted in marine engines.

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