Balanced Type Overburden Drilling System
The Gamma DTH hammers are produced from the latest technology and highest quality materials under strict quality control.

When drilling in soft and loose ground with scattered boulders, the soil and clay are caved in. This creates drilling difficulty to withdraw the DTH drilling equipment and lowers the drilling speed. To overcome this problem, MAXA manufactures the "Balanced Type" (BT) Overburden Drill System to enable drilling and lowering the casing simultaneously. This prevents the soil from collapsing into the drilled hole.

The systems are designed to drill the hole diameters bigger than the casing diameter. When reaching the required drilled depth, the DTH hammer and BT Overburden Drill System can be withdrawn from the hole. If the bed-rock level is reached and further drilling is needed, you can simply change the bit to a conventional DTH bit and drill.

We developed the "Balanced Type" (BT) overburden systems for driving casings up to 914.4mm (36") O.D. casings. Each system consists of a guide device, wing bits and locking system. The wing bits expand and retract concentrically so the system can drill a straighter hole. The wing bits are closed by rotating the system in reverse direction to allow withdrawal of the BT system and D.T.H. drill string when reaching required depth. The wing bits can be replaced separately when they are worn out.

Download Datasheet
Balanced Type Overburden Drilling System Specifications
System Bit Size No. of Wings Outer Diameter of Bit (mm) Applicable Casing (mm) Hammer Shank
Expanded Retracted Outer Diameter Max Wall Thickness
BT190 2 237 190 219.1 6.3 DHD360, QL60, SD6, XL6, MACH 60
BT215 2 277 218 254 8 DHD380, QL80, SD8, MACH 80
BT230 2 300 230 273 12.5 DHD380, DHD380S, QL80, SD8, MACH 80
BT235 2 300 235 273 10 DHD380, DHD380S, QL80, SD8, MACH 80
BT240 2 300 240 273 8 DHD380, DHD380S, QL80, SD8, MACH 80
BT275 3 350 275 323.9 12.5 SD10, N100
BT280 3 350 280 323.9 10 SD10, N100
BT355 3 432 354 406.4 12.5 N120, DHD112, SD12, K270, N125, N120S, SD15, K320
BT360 3 432 359 406.4 10 N120, DHD112, SD12, K270, N125, N120S, SD15, K320
BT445 3 535 445 508.8 14.2 N180, SD18, K350, K370, K410
BT450 3 535 450 508.8 12.5 N180, SD18, K350, K370, K410
BT545 3 637 545 610 16 N180, SD18, K350, K370, K410
BT548 3 637 548 610 14.2 N180, SD18, K350, K370, K410
BT550 3 640 550 610 12.5 N180, SD18, K350, K370, K410
BT640 3 743 640 711 16 N240, K520
BT643 3 743 643 711 14.2 N240, K520
BT647 3 743 647 711 12.5 N240, K520
BT738 4 848 738 813 16 N240, K520
BT740 4 848 740 813 14.2 N240, K520
BT745 4 848 745 813 12.5 N240, K520
BT835 4 953 834 914.4 16 N240, K520, XL240, C330, K610, K700
BT838 4 953 838 914.4 14.2 N240, K520, XL240, C330, K610, K700
BT840 4 953 841 914.4 14.5 N240, K520, XL240, C330, K610, K700

Specifications are subject to change without notice.