Bit or bit element > Bit with leading portion (e.g., pilot) forming smaller diameter initial bore > Impact type > Plural larger diameter steps > Patents

Browse by:

Browse by Category: Main > Construction

Class Information
Number: 175/390
Name: Boring or penetrating the earth > Bit or bit element > Bit with leading portion (e.g., pilot) forming smaller diameter initial bore > Impact type > Plural larger diameter steps
Description: Apparatus in which the cutting edges of the impact bit are arranged so that the boring outline of the bit will describe at least two peripheral axial steps.

Patents under this class:

Patent Number	Title Of Patent	Date Issued
5205366	Superposed drilling device	Apr. 27, 1993
4858703	Self-propelled subsoil penetrating tool system	Aug. 22, 1989
4749050	Impact tool for tunneling	Jun. 7, 1988
4317595	Chisel for a crust breaking facility	Mar. 2, 1982
4144941	Directional impact tool for tunneling	Mar. 20, 1979
4100979	Pneumatic percussion boring device	Jul. 18, 1978
RE29300	Rotary percussion earth boring bit	Jul. 12, 1977
4016944	Pneumatic hammer-auger earth boring apparatus	Apr. 12, 1977
3960223	Drill for rock	Jun. 1, 1976