Loads on Friction Props on a Longwall Face

Based on underground measurements made at the Nova Scotia coal mines of the Dominion Coal Company, Limited, this paper presents a comparison between the physical properties of hardwood packs and steel friction props when used for longwall support. The probable loads sup-ported by steel friction props on a longwall face at both the Dominion No. 20 Colliery and the Princess Colliery are delineated, and the results of the tests are presented in graphical form. It is concluded that the steel friction props are more efficient than the hardwood packs that they replaced as roof supports. Introduction AN evolution in the methods of longwall face support is taking place in the Sydney coalfield. Longwall face support had consisted primarily of timber props and hardwood packs. In 1957, however, at the Princess Colliery, Sydney Mines, Nova Scotia, the first longwall was equipped with steel friction props. At the present time, eleven longwall faces are supported on wood and sixteen faces are carried on steel friction props.