Railway and Locomotive Engineering; A Practical Journal of Railway Motive Power and Rolling Stock Volume 8

Railway and Locomotive Engineering; A Practical Journal of Railway Motive Power and Rolling Stock Volume 8

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1895 edition. Excerpt: ...above a tool. An engine is down a bank, and the wreck-master wishes to haul it ii the direction of least resistance, or by the way that it can be drawn back to the track with the least labor. The locomotive or wrecking-car engine used to supply the power cannot be put in a position to pull directly upon the wrecked engine, so a snatch block is anchored in the right position, and through it the force to do the hauling is transmitted in the direction required.' "Why would a strong ring not be as good as the snatch block or the single pulley?" asked Palmer. "That brings up a question of friction," replied Kinvig. "There are two kinds of friction which we are all very# familiar with in shop and railroad work. When you roll a pair of wheels on the rails they are easily moved, but if you try to slide them a great deal of strength must be exerted. One is a case of rolling friction, the other is sliding friction. A rope passed over a pulley that revolves, moves by rolling friction; when a rope is moved over a bar or thrcvugh a ring, it has to be moved by sliding friction. In the latter case the work lost in friction is very great. "We all know that a wheel can be rolled much easier than it can be slid," said Palmer, "but a flexible thing like a rope sliding over a solid bar ought not to give much greater resistance than it does rolling over a pulley. "That is where you are wrong," replied Kinvig. "I will show you the difference by experiment in the machine shop next lesson night. At present, you have to take my word for the friction under the two conditions. "With large, well-made pulley blocks, the loss from friction is very small. Within certain limits, the larger the sheave of a...show more

Product details

  • Paperback
  • 189 x 246 x 24mm | 844g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236926838
  • 9781236926838