Soil displacement hammer

Abstract: The invention provides a steerable soil displacement hammer for driving holes in the ground. This comprises a substantially cylindrical body (1) and a soil displacement head (2) at a forward end of the body. The head is of larger diameter than the body so as to tend to create an enlarged hole around the body when the head is driven through the ground. Means (3,4) are provided at the rear end of the body for directing said rear end away from the centre of this hole.

Description: 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. Soil displacement hammers, commonly referred to as "moles", can be used to install pipes, cables or conduits in the ground without the necessity for excavating a continuous trench. Soil displacement hammers of this kind are described, for example, in GB-A-2 134 152 and GB-A-2 147 035. WO 87/03924 describes a steerable soil displacement hammer. This is characterised by a retractable baffle member mounted adjacent the forward end of the body. When the baffle member projects transversely from one side of the body, the soil displacement hammer is caused to describe a curved path in the ground. DE-A-2 364 846 also describes a steerable soil displacement hammer. The body is formed in two parts, a forward end and a rear end, with pivot means in between. An object of the present invention is to provide a soil displacement hammer with improved steering means. The present invention thus provides a soil displacement hammer for driving holes in the ground, comprising a substantially cylindrical body, a soil displcement 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, wherein the head is of larger diameter than the body so as to tend to create an enlarged hole around the body when the head is driven through the ground, steering means are provided at a rear end of the body for directing said rear end of said body away from the centre of the hole, said steering means including a member having a forward end and a rear end, and pivot means connecting said forward end of said member to the rear end of said body, characterised in that said member is of substantially the same diameter as said head, is of relatively short length compared to said body, and is tapered towards its forward end, whereby said soil displacement hammer describes a straight path through the ground when the member is aligned with the body, and said pivot means enabling movement of said member towards a first periphery of the hole to direct the rear end of said body towards the opposite periphery to cause the soil displacement hammer to describe a curved path in a direction towards said first periphery. Reference is now made to the accompanying drawing, which is a diagrammatic representation of an embodiment of the invention. With reference to the drawing, the machine is a pneumatically operated soil displacement hammer operating in conventional manner from an external air supply via a flexible hose. The construction of such a machine is well known to those in the art and therefore does not need to be further described here. The machine comprises a cylindrical body 21 and a soil displacement head 22 at a forward end of the body. The head 22 is of larger diameter than the body 21 so that, as the machine is driven through the ground, an enlarged hole is created around the body. The machine also has a back-end 23 which is enlarged to around the same diameter as the head. The back-end is pivoted about a central point 24 and can move through an arc in any direction across the back of the machine. This movement of the back-end of the machine is achieved by suitable power operated devices and is controlled by the operator of the machine. The machine and back-end do not revolve and no extra thrust is necessary to the back; only the air hose, power supply to the movable rear end and tracking equipment are connected to the machine. When the machine is to be driven in a straight line the swivelling back-end 23 is held in a central position by the powdered controls. When the machibe is to be steered the operator causes the back-end 23 to move across an arc towards one edge of the mole. This will cause the rear end of the cylindrical part of the machine to move towards the corresponding side of the bored hole. The head of the machine will then turn in a direction away from that edge.

Claims: A soil displacement hammer for driving holes in the ground, comprising a substantially cylindrical body (21), a soil displacement head (22) 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, wherein the head (22) is of larger diameter than the body (21) so as to tend to create an enlarged hole around the body when the head is driven through the ground, steering means (23, 24) are provided at a rear end of the body for directing said rear end of said body away from the centre of the hole, said steering means including a member (23) having a forward end and a rear end, and pivot means (24) connecting said forward end of said member (23) to the rear end of said body (21), characterised in that said member (23) is of substantially the same diameter as said head (22), is of relatively short length compared to said body (21), and is tapered towards its forward end, whereby said soil displacement hammer describes a straight path through the ground when the member (23) is aligned with the body (21), and said pivot means (24) enabling movement of said member (23) towards a first periphery of the hole to direct the rear end of said body towards the opposite periphery to cause the soil displacement hammer to describe a curved path in a direction towards said first periphery.

Inventors: KAYES ALLAN G, KAYES, ALLAN G.
Applicants: KAYES ALLAN G, KAYES, ALLAN G.
Application year: 1989
Main classification: E21B7
IPC codes: E21B7, E21B4