GB705664A - Improvements in telescopic mining props or like devices - Google Patents

Abstract

705,664. Pit props. MURMANN, W. Sept. 13, 1950 [Oct. 1, 1948 ; June 18, 1949], No. 22534/50. Class 20 (2) A telescopic pit prop comprises flat metal members on one part presenting a longitudinal edge to be sheared by a cutting member on the other part. In Fig. 1 flat metal plates 3 project from slots in the upper part 1 of the prop and are sheared in succession by the upper edge 4 of the lower part 2. Fig. 4 (not shown) shows a similar arrangement for a circular mine casing comprising a circle of telescoping tubes. Another modification comprises shearing members having pairs of oblique flanges 15 bolted on both sides of an I-section prop 14 and adapted to be sheared by the upper part 19. Triangular members 17 support the flanges against buckling internally or externally at 23 when the shearing members are inverted as at 22. Fig. 10 shows a section of a prop having U-shaped rails 26 fitting between the flanges of the I-section lower prop 24 and the edges of the rail are sheared by two oppositely sloping cutting edges. In a further modification, Figs. 13, 14 (not shown), flat oblique opposed shearing sections are clamped between roof shaped members between the flanges of an I-section prop. In Fig. 16 the metal members 109 which are sheared by the lower edges of the upper prop part 101 are held between the two U-section irons 104 forming the lower prop part which are clamped by straps 105 and bolts 107 slotted to receive clamping wedges 108. In a modification the members 109 are of angle section. In a further modification a round wooden upper member is provided with a shoe for shearing and the lower cylindrical member is in two halves clamped together.