Patent ID: 8146681

Claim:
A drilling tool, comprising: a drilling head ( 2 ) for forming a bore ( 5 ); a hydraulically driven device ( 21 ) for advancing the drilling head ( 2 ) in the bore ( 5 ); rinsing means ( 8 , 11 , 12 ) for rinsing the bore ( 5 ) with a rinsing fluid ( 7 ); a first flow limiter ( 30 ) arranged in hydraulic conduit means ( 25 ) of the advancing device ( 21 ) for adjusting an advancing speed with which the advancing device ( 21 ) advances the drilling head ( 2 ) in the bore ( 5 ), the first flow limiter ( 30 ) having a pressure-actuated adjusting member ( 38 ) for adjusting flow of a hydraulic fluid in the hydraulic conduit means ( 25 ) in accordance with flow of the rinsing fluid ( 7 ) in the rinsing means; means for transmitting pressure of the rinsing fluid to the adjusting member ( 38 ) and formed as at least one of mechanical, hydraulic and pneumatic element for actuating the adjusting member ( 38 ) in response to change of pressure of the rinsing fluid ( 7 ), and a second flow limiter ( 52 ) arranged in conduit means for rinsing means and having a pressure-actuated adjusting member subjectable to pressure of the hydraulic fluid.