Frost & Jacobs
Turbodrill with a reduced drilling fluid pressure on a floating piston
 A turbodrill of the type having an annular floating piston between a tubular housing and a bit drive shaft for bounding the top of a lubricant chamber and the bottom of a drilling fluid chamber. The lubricant chamber contains oil for lubricating a bearing supporting the drive shaft in the adjacency of its bottom end. The drilling fluid chamber receives a fraction of drilling fluid (i.e. mud) from a turbine located higher in the housing. For making the mud pressure in the drilling fluid chamber approximately equal to the mud pressure in the drill hole (annulus) around the turbodrill, a seal is provided which restricts the influx of the mud from turbine to drilling fluid chamber. Further a passageway is formed through the housing for placing the drilling fluid chamber in constant fluid communication with the annulus. 
Kabushiki Kaisha Komatsu Seisakusho
E E F Y
E21B E21B F03B Y10S
inventional inventional inventional additional
Akio Masauemon
Ota Kajikawa