The pneumatically driven soil displacement hammer displaces the soil creating a void into which socket-less short or long pipes up to OD 160 made of plastic (PE, PVC or PE-X) or cables depending on the soil type up to 25 m lengths are pulled, either immediately or subsequently. This enables the safe under crossing of traffic ways and production of house connections for gas, water, etc. exactly on target and completely without the need for open trenches.
Conditions of application
Firstly, the soil to be penetrated must be sufficiently displaceable. The soil displacement hammer is placed on a starting cradle and launched from inside a pit. By using a telescopic sight, aim is taken and the height and sides of the machine are adjusted accordingly. The soil displacement hammer is moved forward by a piston driven with compressed air (normal jobsite compressor), external friction on the outer machine casing is required for the forward movement, if this is missing for example in soft or loose, soils, external static pushing support can be added.
Two basically different systems are possible:
Fixed Head single stroke method
The piston applies impact to the casing and drives the complete displacement hammer and the attached pipe string forward with one blow (rigid system) or
The piston first strikes the mobile chisel and multi-cutter cone and then the casing, which means that the soil displacements hammer moves forward in two distinct steps.
Moving Head 2-stroke-method
The soil displacement hammers achieve an installation speed of 15 m/h, depending on the soil, they are equipped with a reversing gear and the ground cover should be at least ten times as thick as the diameter of the casing to avoid heaving of the ground surface. The GRUNDOMAT with its mobile multi-cutter cone is simply reversed with a lever, a plug-on head with integrated transmitter or a built-in transmitter in the hose makes location possible, but it is not intended for steering. The soil displacement method is described in the German guideline ATV-A 125 and in the GW 304 Pipe Laying as well as in other German standards.