Hydraulic pit prop assembly - has outer prop tube with attached prop foot and inner prop tube inside outer longitudinally movable against spring force

摘要

The inner prop tube is displaceable by a piston fitted in a pressure fluid-tight manner in the outer prop tube and a device for lift limitation of the inner prop tube is provided. A union ring is fixed to the outer prop tube for guiding the inner prop tube, together with a set valve. For lift limitation of the outer prop tube (10) in a distance from the prop foot (12) corresp. to the desired lift of the inner prop tube (15), a hole (26) is provided through the wall of the outer prop tube and when the inner prop tube travels out of the outer tube (10) the piston (19) of the inner tube travels over it. USE/ADVANTAGE - To simplify the lift limitation of an inner pit prop tube.