The bearing which supports the rotor of this tool is subjected to both rotary and side loads. The tool turns at between 6 and 10 rpm, depending on the load. The drive end of the rotor is supported directly by the shaft of the hydraulic motor, which powers the tool. The rotor is stainless steel and operates in sea water. The tool nose has to fit in an ISO standard "bucket" interface which houses the drive shaft turned by the tool, as well as reaction cut-outs to react the tool torque.

In order to make the tool easy to locate on the drive, the drive socket is sprung. This allows the socket to be pushed into the rotor by the drive shaft. When the tool rotates, the spring pushes the socket onto the shaft when they align. This mechanism uses a considerable portion of the diameter of the rotor.

If a conventional ball or roller bearing was used, the diameter of the tool would be too large to fit into the interface bucket. Also, lubrication and sealing would be both complex and heavy. The solution was to use a pressed-in plastic iglide® bearing.