Replacing mains
AssigneeBritish Gas Corporation
InventorsMalcolm Wayman, Geoffrey I. Mood
Life of this patent
Estimating the term…
Abstract
The invention relates to a self-propelled apparatus 1 for replacing main such as a gas main 2, comprising a single double acting hydraulic piston and cylinder combination 3 connected with slidable devices 4, 6 operable by the device for step-by-step movement of the apparatus through the main on alternate strokes of the combination, the devices 4 and 6 being operative in only a forward direction to slide to grip the main, the apparatus drawing a vibratable breaker device 20 (FIG. 2) or 30 (FIG. 3) through the main, the device being vibratable to precess about an axis and the device 30 being vibratable by percussive means longitudinally of the main.
Claims10
Appparatus for self-propelled passage through a main for breaking the same in situ, comprising a traction unit operable to draw the apparatus through the main in a step-type action, and a breaker device connected with the traction unit to the rear thereof for breaking the main as the apparatus passes therethrough, said traction unit comprising a double-acting piston and cylinder combination and a device carried by the combination and operable thereby so that on successive strokes of the combination the device respectively slides along or grips the interior surface of the main in said step-type action whereby progressively to move the apparatus through the main, said device comprising a first member connected with the combination and a second member slidably mounted on the device for movement transversely to the longitudinal axis of the combination, said first and second members having respective surfaces in mutual sliding engagement, which surfaces are inclined to said longitudinal axis and slide relatively in response to a stroke of the combination to produce said movement transverse to said longitudinal axis, said device further comprising biassing means urging said device towards a condition in which said device grips said interior surface.
Apparatus for self-propelled passage through a main for breaking same in situ, the apparatus comprising at least one assembly including a body and two feet engaging said main, a tool including a breaker device and double-acting hydraulic ram means positioned between and operatively connected to said body and to said tool, said assembly also comprising first and second surface means in mutual sliding engagement and inclined to the lengthwise direction of said main, said first and second surface means being connected, respectively, to said body and to at least one of said feet, said assembly also comprising a spring arranged between said body and said one of said feet, said spring causing wedge action of said first and second surfaces to force said feet against said main and to keep said surfaces in engagement, whereby a first stroke of said ram means applies force to said body in a first sense so as to reinforce said wedge action and said feet grip said main as said tool advances there along and whereby a second, succeeding stroke of said ram means applies force to said body in a second sense opposite to said first sense so as to reduce said wedge action, said feet then sliding along said main as said assembly advances therealong.
Dependencies are inferred from the claim text.