Book Description

Excerpt from American Railway Engineering Association Bulletin, 1982, Vol. 83 Since it is the difference in rail temperature, from its initial or laying temperature, that determines the magnitude of the thermally induced rail forces, proper selection and control of the continuously welded rail installation temperature is of great importance. Consequently, many railroads have well defined installation temperatures for different geographical lo cations. When the ambient temperature at the time of installation is below the recommended installation temperature, the rails are artificially brought to the proper temperature, either through heating of the rails or mechanically stretching them to the appropriate lengths. Conversely, when the ambient temperature at the time of installation is above the recom mended installation temperature, the rails are cooled, usually by spraying them with a coolant. However the same mechanical and creep forces that result in force build up, also work to build up stresses in the rail, thus in effect changing the laying temperature. Furthermore, rails installed in and near curves often undergo expansion and contraction cycles which result in a shifting of the track, usually seen as a change in the curvature. This often occurs in conjunction with maintenance activities, such as surfacing. This behavior can also change the equivalent installation temperature, so that it is no longer the same as the initial laying temperature, and sometimes is significantly different. In fact, in many cases, this force-free temperature' is no longer known. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.