Displacement Moles


The soil displacement method is a method for underground pipe installation which has been established for the last three decades.

Technical Information:

A displacement hammer, driven by pneumatics, creates a cavity underground, ready for pulling in short or long pipes made of plastic and metal, preferably without socket ends, up to DN 200, but also any type of cable in drill lengths up to 40 m (depending on the soil quality), either simultaneously or in a second working step. This allows trenchless traffic route crossings, private service line installations, the preparation of anchoring, by-passing obstacles and supporting further measures.

Plant Description:

One main property of the mole is the chisel head system. First, the percussion piston, running ahead in advance to produce a pilot bore in the first cycle, strikes the chisel. This allows the mole to work with extreme precision, even in stony grounds. Immediately after the stroke on the chisel, the piston also strikes the protective casing directly, which is then pulled in together with the pipes attached. Even resistance peaks and casing friction are easily overcome - therefore the propulsion speed is increased immensely.

It is possible to switching the mole from forward to backward motion, and vice versa, is performed with a lever of the control unit outside the pit.

The advantages at a glance:

  • Higher installation speed due to the chisel head system, slighter return stroke.
  • Chisel head system for easily overcoming resistance peaks and casing friction in all soil types. 
  • Low air consumption.
  • Control unit and lubricator in one compact structural element between machine and compressor.
  • Light weight hoses.
  • Connection hose can be exchanged without disassembling the end cone or the pull sleeve.
  • Chisel head and piston - specially hardened.
  • Piston runs in high-quality sliding bushes - no metal contact.
  • Maximum protection against corrosion.  

Coffeys Experience:

Coffey construction have carried out several contracts using the moles on various site around the country as part of the main contract works particularly for regional water schemes, infrastructural contracts for all utilities and also for water meter installations.

Curragh Regional water supply scheme for water pipes.
Ennis Bypass Infrastructural Works  
Ennis Bypass Infrastructural Works

Coffey Group, Athenry, Co. Galway, Ireland Tel: +353 91 844356 Fax: +353 91 844519 Email: info@coffeygroup.com