The eccentric system is recomended when overburden situation must be solved.When using the eccentric system ,casing the hole is simultaneous with the drilling operation.Eccentric system is capable of drilling in formations such as tough overburdens, gravel ,sand incoherent rocks, boulders and clay.
Eccentric system features:
- a guide device to fit all polpular brands of Down the Hole Hammers
- a reamer that pivots around an offset shaft on the pilot bit and creates a hole larger than the casing diameter
- a pilot bit
When the hole has been drilled and cased , the eramer is closed by reversing the direction of rotation in a single turn.The reamer and pilot bit can be retreacted from the cased hole
| Model | O.D. Casing | Pilot Bit Diameter | Hole Opener | Hammer Size |
| 4 | 4.5″ – 115 mm. | 3.54″ – 90 mm. | 4.85″ – 123 mm. | 3″ |
| 5 | 5.56″ – 141,3 mm. | 4.53″ – 115 mm. | 5.95″ – 151 mm. | 4″ |
| 6 | 6.625″ – 168,3 mm. | 5.5″ – 140 mm. | 7.44″ – 189 mm. | 5″ |
| 7 | 7.625″ – 193,7 mm. | 6.52″ – 165 mm. | 8.32″ – 211 mm. | 6″ |
| 8 | 8.625″ – 219,0 mm. | 7.51″ – 190 mm. | 9.30″ – 236 mm. | 6″ |
| 10 | 10.75″ – 273,0 mm. | 9.48″ – 240 mm. | 12.125″ – 308 mm. | 8″ |
E’ raccomandato l’utilizzo di tubi di rivestimento a saldare o filettati sinistri con spessore di 1/4″ (6.3 mm.)
