| 摘要 |
862,783. Mine-roof supports. VANWERSCH, P., VANWERSCH, L., and VANWERSCH, A. March 6, 1959 [March 6, 1958], No. 7948/59. Class 20(2) A connection for tongue-and-fork roof support bars 1, 2 which are symmetrical about a horizontal mid-section, is erected by inserting a pivot pin 3 into holes in the fork and into a slot 5 in the tongue and by engaging one of the wedging surfaces 6 on a non-rotating slide 4 with the tongue. When the slide is in 'mid' position, the region 8 provides clearance for the tongue to enable the bar 1 to be swung into or down from a near-horizontal position. A modified arrangement (Figs. 6, 7, 8, not shown) uses a plain hole for the pin 3 in the tongue and an auxiliary pivot pin to assist in aligning the bars to insert the main pin 3; the arrangement also allows a continuous straight line to be maintained over the upper surfaces on the bars and their joint. |
