REVERSE HEAT ENGINE'S ROLE IN UNIT TRAINS

Reverse heat engines are essentially an assembly of component parts accomplishing a transformation of work into heat and the dissipation of this heat into the atmosphere. In doing this work a reverse heat engine must provide yielding resistance of such initial sensitiveness, combined with ultimate high capacity, that any of the draft or buffing actions, small or great, incident to the switching, humping, starting, and stopping of railway cars, may be modified to the lowest possible limits of stress. When a moving freight car impacts a stationary car, or when train slack is run in or out with violence, there is a transfer of energy from one car to the other. This transfer becomes more rapid as the draft gear resistance increases. At the same time the inertia force of a stationary car becomes less and less, until the steadily increasing value of the push exerted by the draft gears starts movement of the stationary car. Thus a reverse heat engine is nothing more than an efficient freight car draft gear. There are five types of standard pocket draft gears in use today: All-steel friction, combined rubber-friction, all-rubber, hydraulic-friction, and silastic rubber. Since a draft gear is primarily a cushion, it develops a cycle of work during its closure and release under the various intensities of draft and buff impact, either when operating in the moving train or when it is being collided singly or in groups of cars during train make-up. This draft gear cushioning cycle is evaluated exactly like the steam or gas engine work cycle. Engine action is considered positive on the basis of heat being changed to work, causing acceleration. The draft gear cycle is negative, work being changed to heat, causing deceleration. The importance of maintenance of draft gears with too much slack is emphasized.

  • Supplemental Notes:
    • In Coal production and transportation: third annual conference, 1977; San Francisco, PLM, Inc.
  • Corporate Authors:

    PLM, Incorporated

    1 Embarcadero Center
    San Francisco, CA  United States  94111
  • Authors:
    • Wallace, W D
  • Publication Date: 1977

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Filing Info

  • Accession Number: 00174365
  • Record Type: Publication
  • Source Agency: Energy Research Abstracts
  • Report/Paper Numbers: Conf Paper
  • Files: TRIS
  • Created Date: May 18 1978 12:00AM