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US 5,669,739 AGranted
Prestressing of mine props
AssigneeHL&H Timber Products (Proprietary) Limited
InventorGraham Heath Clarke
Life of this patent
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AssigneeHL&H Timber Products (Proprietary) Limited
InventorGraham Heath Clarke
Estimating the term…
The mine prop prestressing device (10) has a tube (12), a cup-shaped member (14) inside the tube which has a base (18) and a cylindrical side wall (20) fixed internally to the wall of the tube. A counter-member is also fixed to the tube in opposition to the cup-shaped member, and a valved inlet leads through the wall of the tube for the purpose of introducing a pressurised fluid into the tube between the base of the cup-shaped member and the counter-member. If the fluid is under sufficiently high pressure, the base of the cup-shaped member and the counter member are deformed apart from one another. The counter-member is typically in the form of an identical or similar cup-shaped member (14). The device (10) is a component part of a mine prop which includes a plunger (36, 38) inserted slidably into the tube so as to locate in a cup-shaped member. When pressurised fluid is introduced into the tube, the plunger is driven telescopically out of the tube.
A mine prop prestressing device comprising a tube, a flexible cup-shaped member inside the tube, said cup-shaped member having a base and a cylindrical side wall permanently fixed internally to the wall of the tube, a counter-member which is fixed to the tube and which spans across the tube in opposition to and adjacent the base of the cup-shaped member, and a valved inlet leading through the wall of the tube for the purpose of introducing a pressurised fluid into the tube between the base of the cup-shaped member and the counter-member so as to deform the base of the cup-shaped member and the counter member apart from one another.
Dependencies are inferred from the claim text.