Boring or penetrating the earth – Processes – Boring horizontal bores
Patent
1995-08-09
1996-09-17
Dang, Hoang C.
Boring or penetrating the earth
Processes
Boring horizontal bores
173150, 173156, 173189, 175122, 175162, E21B 702
Patent
active
055559476
DESCRIPTION:
BRIEF SUMMARY
This invention concerns a mole launcher from which is propellable under fluid power a string of drill pipes having at an end of the string remote from the launcher a mole operable to bore an underground passage.
The invention also concerns a method of operating a mole launcher.
The aforesaid passage may be bored to receive, for example, an underground pipe or cable.
The string of drill pipes may be used to supply power therethrough to actuate the mole for it to perform passage boring operations.
Moles are known in which the mole operates percussively to bore the passage in response to fluid power, for example pneumatic power, applied to the mole through the string of drill pipes which is connected to the mole and is pushed along the passage behind the mole by fluid power, for example hydraulic power.
An object of the invention is to provide a mole launcher capable of being constructed to provide a powerful fluid powered thrust acting on the string of drill pipes in the direction of boring and also capable of providing a powerful extraction force for pulling the string from the bored passage.
Another object of the invention is to provide a mole launcher capable of being constructed so that in its transportation state it can be considerably shorter than when it is in its operating state for pushing or pulling on a string of drill pipes.
According to a first aspect of the invention there is provided a mole launcher from which is propellable under fluid power a string of drill pipes having at an end of the string remote from the launcher a mole operable to bore an underground passage, piston and cylinder unit comprising a cylinder having a piston working therewithin and acting to reciprocate a connecting rod as said piston reciprocates, said cylinder being mounted on said support means and being capable of longitudinal movement relative to the support means, connecting means for detachably connecting the connecting rod to a said drill pipe at an end of a said drill pipe string when the launcher is in use and the mole is at the other end of the string such that when the connecting rod performs linear strokes relative to the cylinder the linear movement of the rod is applied as linear movement to the drill pipe string which is pushed or pulled by said movement of the connecting rod, said cylinder being movable longitudinally relative to the support means between first and second positions, first disengageable restraining means for holding the connecting rod substantially stationary relative the said support means whereby under fluid power the cylinder can be moved from said first position to said second position and vice-versa, second disengageable restraining means for holding the cylinder substantially stationary longitudinally in said second position whereby under fluid power applied to the cylinder said connecting rod can be reciprocated relatively to the cylinder such that on an outward movement from the cylinder said connecting rod exerts pushing force on the string of drill pipes connected to the connecting rod in the course of use of the launcher.
The cylinder, when in said second position, may project beyond said support means and disengageable engagement means may be provided on the cylinder and said support means to restrain and support the cylinder from lifting away from said support means.
While moving between the first and second positions the cylinder may be slidably supported by a guide on the support means.
Said connecting means for connection to a drill pipe may be mounted on a slider slidably mounted on the support means and said connecting rod may be attached to said slider. The connecting means may be movable relative to the slider in opposite directions along which the slider is movable by said connecting rod.
Said slider may be in sliding engagement with said support means.
The support means may be tiltable, relative to the ground, by operation of fluid pressure actuated jack means.
The mole launcher may be provided with detachable mechanical restraining means to oppose widening of an angl
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Bunker Roger S. A.
Goodall David J.
Bonuscentre Limited
British Gas
Dang Hoang C.
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