Concentric Overburden Driling System (High Air Pressure)

Type	Hole Diameter (mm)	NO. Air Hole	Gauge Buttons	Front Buttons	Casing Size ( Wall Thickness * Outerdiameter)	Size (Diameter*L)	Weight (KG)	Hole deep(m) (f=4~6)	Match DTH Hammer
DR146	Φ156	3	Φ14*6	Φ14*5	Φ146(5~7.5)	Φ129X405	24	300~1000	DR340
DR168	Φ182	3	Φ14*6	Φ14*6	Φ168(5~10)	Φ146X550	30	300~1000	DR350
DR183	Φ196	3	Φ14*8	Φ14*8	Φ183(5~10.5)	Φ161X688	38	300~1000	DR350/360

Working Principles:
A. When drilling, the reamer swings out and drills a hole larger than the externa diameter of the casing tube.
B. When the required depth has been reached, the drill is reversed and the reamer swings in to its minimum diameter, allowing the bit to be lifted up through the casing, which is left in the hole.
C. Drilling can continue with an ordinary DTH drill bit.

HREE reamer wings advantages:
1. multi-orientation simultaneously crush, so as to bear stress evenly and subsequently impact resistance.
2. dislaging easily
3. Drilling rod and casing could accelerate following up.
4. Operation, aseemble and unassembled the equipment is easy.
5. Multi-axis suspension is adopted, to avoid reamer from falling of.