Questions and Answers on Pumps and Pumping Machinery (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ...to the pump. 300. Q. If a short strainer is used, why should it be much larger than the suction pipe? A. Because the actual area of openings should be about double the area of the pipe, to provide for partial closing of it by foreign matter. 301. Q. Describe the main features of a crank and fly-wheel boiler-feed pump. A. It consists of a steam cylinder containing a piston, the rod of which extends into the water cylinder. A piston in this cylinder acts directly on the water, and forces it out through suitable valves. 302. Q. How is steam admitted to and exhausted from this cylinder? A. Usually by a plain " D " slide valve. 303. Q. Is the supply of steam cut off early in the stroke, to allow for expansion? A. No; it is admitted during about seven-eighths of the stroke. 304. Q. How is the motion reversed in this kind of pump? A. By means of a crank shaft, and the momentum of a cast-iron fly-wheel. See Fig. 51. 305. Q. How are connections made in this case? A. The crank shaft, carrying the fly-wheel, is next to the water cylinder. The crosshead is wide enough to carry one end of a connecting rod on each side of the water cylinder. The other ends of these rods are rigidly connected to a supplementary crosshead, the center of which is fitted with crank-pin boxes, gib, strap and key, according to common practice in steamengine design and construction. 306. Q. Does this form a center or side crank? A. It is a center crank, because a bearing is provided on both sides of it. 307. Q. How many fly-wheels are used? A. In this particular case only one is used, but two could be provided with good results. 308. Q. What advantage would be gained by adding another wheel? A. It would give a more uniform motion to the machine and allow it to be run at a lower speed....