Percussion boring tool for producing underground passages for electrical and water services

The percussion boring tool comprises a body (1) containing a firing pin (4) able to displace alternately in the body and crossed by a central channel (5). Front (7) and rear (8) chambers are formed between the body and the firing pin. A separate compressed air distribution system for each chamber comprises channels or passages (12,14) which admit compressed air into the chambers and channels or passages (13,15) which exhaust the compressed air from the chambers. There is a compressed air supply passage (16). The air distribution system is realised in the form of two distribution pins (9,10) each passed through by the channels. Each pin is fixed to the body ends (2,3) by elastic locking parts (11). A compressed air supply pipe (17) is connected to one of the body ends (3). Le dispositif à effet de percussion comprend: un corps contenant un percuteur apte à se déplacer alternativement dans ledit corps et traversé par un canal central, un système de distribution d'air comprimé comportant des canaux d'admission d'air comprimé dans des chambres avant et arrière et des canaux d'échappement hors de ces chambres. Le système de distribution d'air à l'admission (16, 12, 14) et à l'échappement (13, 15) est distinct pour chacune desdites chambres avant et arrière (7, 8).Application à la pose sans tranchées de nouvelles canalisations souterraines et à la reconstruction d'anciennes canalisations.