Boring or penetrating the earth – With signaling – indicating – testing or measuring – Tool position direction or inclination measuring or...
Patent
1987-08-13
1990-05-01
Neuder, William P.
Boring or penetrating the earth
With signaling, indicating, testing or measuring
Tool position direction or inclination measuring or...
175 73, E21B 704
Patent
active
049210556
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a soil displacement hammer. More particularly, the invention relates to a steerable soil displacement hammer for driving holes in the ground, and a method of tracking its position as it moves through the ground.
Soil displacement hammers, commonly referred to as "moles", can be used to install pipes, cables or conduits in the round without the necessity for excavating a continuous trench. Soil displacement hammers of this kind are described, for example, in GB-A-2134152 and GB-A-2147035. Existing moles do not have the capability of being steered or tracked during their passage through the ground. This restricts their application to use over relatively short distances. Furthermore, the directional stability of conventional moles can be affected by the nature of the ground, resulting in deviations from an intended route, which cannot be detected or corrected.
An object of the present invention is to overcome these limitations.
According to one aspect of the invention, there is provided a soil displacement hammer for driving holes in the ground, comprising a substantially cylindrical body, a soil displacement head at a forward end of the body, a longitudinally reciprocable striking member housed within the body, and an anvil member within the body adjacent its forward end and adapted to receive hammer blows from the striking member to cause the body to be driven forward, characterised in that a retractable baffle member is mounted adjacent the forward end of the body and is movable between a retracted position in which it does not project from the body so that the soil displacement hammer describes a straight path in the ground, and an extended position in which it projects transversely from one side of the body to cause the soil displacement harmer to describe a curved path in the ground.
The baffle member, also referred to herein as a steering plate, can be mounted to slide in and out rom the body, or alternatively it can be hinged to the body. It is preferably capable of moving outwards and forwards eccentrically and at an angle inclined to the cylindrical body of the mole. The diameter of the eccentric steering plate, when viewed in front or rear elevation, may be equal to that of the mole. The plate may be operated hydraulically, pneumatically or mechanically.
The position of the steering plate along the length of the mole will depend on the profile, length and angle of the plate. It is possible to have more than one such plate, and the angle of such plate(s) can be varied to alter the behaviour of the mole. In fact it is possible to make the mole react in completely the reverse manner to that described by changing the angle of the plate(s). Different profiles of the plate(s) will also make the mole react in different ways.
In an alternative embodiment, the retractable baffle member comprises a sleeve portion dependent from a head portion mounted at the forward end of the body, the head portion being adapted to swivel about the said forward end to permit one side of the sleeve portion to project from one side of the body.
The mole is preferably designed to be rotatable about its longitudinal axis, by remote control as it is being driven through the ground. It is then only necessary for the steering plate to be capable of projecting from one side of the body, as the body itself can always be rotated so that the mole can be caused to steer in any desired direction.
There may be one or more steering plates positioned around the circumference of the mole at its front end and operated individually or collectively. The plates may be spring loaded so as to remain in the retracted position within a housing when not activated. The housing containing the plates is attached to the front of the hammer unit and a soil displacement head is fitted in front of the plate housing. The displacement head may rotate freely.
The casing of the hammer unit is preferably contained within a cylindrical earth sleeve so that the mole assembly can be rotated within this sleeve. The outer surface of the eart
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patent: 2350986 (1944-06-01), Collins
patent: 3529682 (1970-09-01), Coyne et al.
patent: 3630295 (1971-12-01), Coyne et al.
patent: 3853185 (1974-12-01), Dahl et al.
patent: 3952813 (1976-04-01), Chepurnoi et al.
patent: 4144941 (1979-03-01), Ritter
patent: 4416339 (1983-11-01), Baker et al.
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