Replacement of mains
AssigneeBritish Gas Corporation
InventorsRoy Streatfield, Francis D. Wilson
Life of this patent
Estimating the term…
Abstract
A mole 1 for replacing an existing main, for example a cast iron gas main, with a new main. The mole 15 is of steel and is inserted into and along the existing main 94. The mole 51 has a front portion comprising a head 52 and a cylindrical body portion and a rear portion 53 having a clamp 54 for clamping a new main to the mole 51. The head 52 has a cutting face 55 for engaging the internal wall of the existing mole 51 therealong. The new main which in use is clamped to the mole 51 is towed along behind the mole 51 to replace the fractured old main 94.
Claims10
A device for replacing or preparing for replacement an existing main with a new main, the device comprising a mole for insertion into and movement along the existing main, the mole having a front portion comprising a head portion provided with a cutting face for engaging the internal wall of the existing main and arranged to cause the wall to fracture and a rear portion provided with means for clamping to the mole the new main or a liner for the bore created by the mole as it moves through the fractured main so that the mole tows the new main or the liner through the fractured main as the mole moves therethrough,
- said cutting face comprising a plurality of blades positioned on the head portion to engage and fracture the wall of the existing main as the mole moves therethrough, all except one of the blades being fixedly mounted on the head portion, said one blade being pivotally mounted on the mole, movable radially outwardly from the mole to engage and fracture the wall of the existing main, and including movable means within the mole to engage said one movable blade to cause it to pivot.
Dependencies are inferred from the claim text.