Concentric Overburden Drilling System with Blocks

Operation Procedure
As drilling begins, the blocks slide down through the grooves on the pilot bit, and the ream drives the casing shoes and tubes into the drill hole
After the drilling process is complete in overburden rock formations, raise the drilling tools, allowing the blocks to close through the grooves. Once this is done, the drilling tools can be pulled out from the drill hole
. Next construction tasks can be carried out

Concentric Overburden Drilling System with Ring Bits

Permanent
1. When drilling starts, the pilot bit drives the ring bit down to the hole, followed by the casing shoe and casing tube.
2. At the bedrock, start the reverse circulation of tools and pull the pilot bit from the drill hole. Leave the ring bit in the hole.
3. Pour the concrete or do the next construction task.

Retrievable
1. After the drilling starts, the pilot bit drives the ring bit down to the hole, followed by the casing shoe and casing tube.
2. At the bedrock, start the reverse circulation of tools and pull the pilot bit back from the drill hole. Leave the ring bit in the drill hole.
3. Pull the casing tube out with the ring bit and at the same time pour the concrete.