Concentric Overburden Drilling System
            You can pull out the pilot bit by rotating the rod, clockwise in case of drifter
            and anti-clockwise in case of DTH Hammer, and continue to drill through
            the ringbit with a conventional bit in solid formation.
For Drifter(=Top Hammer)
Assembled Set
Click for the components
Model Casing OD Max Casing Thickness Ring Bit OD Ring Bit ID Pilot Bit OD Drifter Thread
JOSYM 54D 76.2mm 6mm 85mm 54mm 53mm T25,T32
JOSYM 68D 89.1mm 6mm 98mm 68mm 67mm T32
JOSYM 74D 101.6mm 5.6mm 109mm 74mm 72mm T32,T38
JOSYM 80D 114.3mm 8mm 123mm 80mm 78mm T32,T38
JOSYM 105D 133.4mm 8mm 142mm 105mm 103mm T38,T45
JOSYM 109D 139.7mm 6.6mm 149mm 109mm 107mm T45,T51
JOSYM 116D 152.4mm 10mm 162mm 116mm 114mm T51,T68
JOSYM 127D 168.3mm 10mm 178mm 127mm 125mm T51,T68
In accordance with our policy of constant improvement of the products, we reserve the right to amend design, materials and specifications at any time without notice.          
For DTH Hammer