US 5,051,039 AGranted

Hydraulic steel mine prop

OwnerMartha-Catharina Heiligerinventor

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Abstract

Hydraulic steel mine prop having a bottom ram including an outer cylindrical tube (1) having a cylinder bottom (14) and an end collar (16), as well as a top ram guided coaxially slideably in the bottom ram by the end collar (16) and a guide ring (12). The top ram is a cylindrical tube (2) comprising a piston (9) sealed and guided relative to the inner wall of the outer cylindrical tube (1). A prop head (4), a setting and withdrawal valve (21), an inner extension stroke limiter, and a return spring (6) are also provided. Each of the outer and the inner cylindrical tubes is received at its facing ends by corresponding projections or facing end grooves of the end collar or piston at one end and at the prop head or cylinder bottom at the other end. Seals are provided at least at the piston, the prop head, and the cylinder bottom. An element is provided between the prop head and the piston for taking up tension forces between these two structural parts. A further tension element (7) arranged coaxially to the cylindrical tubes, is attached to the cylinder bottom. The element (7) extends as a holding rod through the piston and has a holding element (8) at its free end. A compression spring (6) is arranged coaxially to the tension element to act as a return spring.

Claims28

Dependent claims

A hydraulic steel prop for mines, comprising a first prop section and a second prop section, one of said first and second prop sections having a prop foot (14, 14', 25) while the other of said first said second prop sections has a prop head (4, 24), said first and second prop sections having an outer cylindrical tube (1) and an inner cylindrical tube (2) slidingly received in said outer cylindrical tube (1), one of said cylindrical tubes having a foot end secured to said prop foot, a first seal between said foot end and said prop foot, the other of said cylindrical tubes having a head end secured to said prop head, a second seal between said head end and said prop head, a guide collar (16) surrounding said outer cylindrical tube for guiding said inner cylindrical tube in said outer cylindrical tube, a piston (9) secured to said inner cylindrical tube for guiding said inner cylindrical tube inside said outer cylindrical tube, a third seal (10) between said piston and said outer cylindrical tube for sealing a compression chamber (26) in said outer cylindrical tube, a first tension member (3) interconnecting said prop head and said piston (9, 9') for taking up axial tension loads, a second tension member (7, 7') arranged coaxially inside said cylindrical tubes and slidably passing through said piston, means (47) securing a fixed end of said second tension member (7, 7') to said prop foot (14, 14', 25), a stop (8) at a free end of said second tension member (7, 7'), a compression spring (6) coaxially arranged around said second tension member (7, 7'), said compression spring (6) having one spring end bearing against said stop (8) and another spring end bearing against a support means (11, 40) for taking up an axial force tending to compress said compression spring, whereby said compression spring (6) has a biasing force tending to displace said piston (9) toward said prop foot, a setting and withdrawal valve (21) in said steel prop, and flow conduit means connecting said setting and withdrawal valve (21) to said compression chamber (26) through one of said prop head and said prop foot.

A hydraulic steel prop for mines, comprising a first prop section and a second prop section, one of said first and second prop sections having a prop foot (14, 14', 25) while the other of said first and second prop sections has a prop head (4, 24), said first and second prop sections having an outer cylindrical tube (1) and an inner cylindrical tube (2) slidingly received in said outer cylindrical tube (1), one of said cylindrical tubes having a foot end secured to said prop foot, a first seal between said foot end and said prop foot, the other of said cylindrical tubes having a head end secured to said prop head, a second seal between said head end and said prop head, a guide collar (16) surrounding said outer cylindrical tube for guiding said inner cylindrical tube in said outer cylindrical tube, a piston (37) secured to said inner cylindrical tube for guiding said inner cylindrical tube inside said outer cylindrical tube, a third seal (10) between said piston and said outer cylindrical tube for sealing a compression chamber (26) in said outer cylindrical tube (1), a tension tubular member (3) interconnecting said prop head and said piston (9) for taking up axial tension loads, and wherein said piston (37) comprises a safety valve (32) which, in a predetermined end position of said piston (37) connects said compression chamber (36) to the atmosphere through a bore (33), through an intermediate chamber (28) between said outer and inner cylindrical tubes (1, 2), and through at least one relief bore (29) connecting said intermediate chamber (28) to the atmosphere, said prop further comprising a spiral tension spring (50) acting as a return spring arranged under tension between said prop head (4, 24) and said prop foot, said return spring (50) being surrounded by said tubular member (3) for taking up tension loads and by a further tube (51), which is attached to said prop foot, said further tube (51), at least in the retracted state of the prop, extending telescopically into said tubular member (3) and surrounding said spiral tension spring (50), wherein said safety valve (32) is operated by said further tube (51) when said piston (37) is in a certain position.

Dependencies are inferred from the claim text.