Facing head has piston mounted in chamber behind drive components and working tool, mixture of oil and air being fed through channels into part of chamber behind piston and then on to drive chamber

摘要

The facing head has a piston (16) mounted in a chamber (24) behind the drive components and working tool (10). An oil/air mixture is fed through channels (28, 28') into the part of the chamber behind the piston and then on to the drive chamber (18). An Independent claim is included for a method of lubrication using the above system.