GB807462A - Metallic pit prop - Google Patents

Abstract

807,462. Pit props. GERLACH, K., and GERLACH, H. April 28, 1955 [May 8, 1954, Aug. 9, 1954, Sept. 30, 1954], No. 12297/55. Class 20(2) A telescopic pit prop has a lower part 2 common to two or more upper parts 1 which are provided, in one embodiment, with fixed heads 5, Fig. 1, which are arranged to support the cap 4 in the immediate vicinity of the neutral axis 6 of the upper prop parts. In other embodiments the cap or caps are supported by rockable heads 10, Fig. 4 which are pivoted about points 11 on or in the immediate vicinity of the neutral axes of the separate upper prop parts, or by a rockable head 31, Fig. 13, mounted in a common head 27 uniting the upper prop parts 1 and adapted to rock about a point in the immediate vicinity of the neutral axis of the united upper prop parts. The rockable heads may be provided with part spherical rockers 12, Fig. 5 (not shown) and Fig. 10, so that the heads are capable of universal pivotal movement. In Fig. 10 a head plate 20 is mounted on the rockable head 12 of each prop part, and the head plate may be in one piece (not shown) or in two or more parts connected by clips 22 or other articulated joints. A transverse element 23 for simultaneously setting both upper prop parts can be secured either to the upper prop parts, or to the setting device. The upper prop parts 1 may be held against excessive transverse movement by means such as a pin 7, Fig. 1, and a spring 8 may be inserted between them. The upper prop parts may be connected with lost motion by means of an element 16, Fig. 8 having inclined elongated holes 18 for connecting bolts 19. The elements 16 provides abutments 17 which limit the inclination of the cap in the case of an inclined setting.