EP 0273139 B1 19920429 - BORING RAM
Title (en)
BORING RAM
Publication
Application
Priority
DE 8700076 U 19870102
Abstract (en)
[origin: US4840237A] A ram boring implement has a pneumatically driven percussion piston (16), which is movable in the axial direction in a reciprocating manner in a housing (12), and a control sleeve (24) which is axially adjustable for reversing the direction of motion of the ram boring implement and is acted upon by the pressure in one (20) of the pressure chambers (18, 20) formed on both sides of the percussion piston (16). The control sleeve (24) can be adjusted by means of a spindle drive (30, 50) by turning a compressed air supply hose (26). According to the invention, the control sleeve is arranged on a core (30, 34), supported in an axially fixed manner on the housing (12), so that the control sleeve itself forms only a relatively small annular effective area (52) acted upon by pressure. This makes it possible for the control sleeve to be moved forward or toward the rear without the compressed air feed having to be interrupted.
IPC 1-7
IPC 8 full level
CPC (source: EP US)
E21B 4/145 (2013.01 - EP US)
Designated contracting state (EPC)
AT BE CH DE FR GB IT LI NL
DOCDB simple family (publication)
US 4840237 A 19890620; AT E75522 T1 19920515; DE 3778668 D1 19920604; DE 8700076 U1 19870219; EP 0273139 A2 19880706; EP 0273139 A3 19890628; EP 0273139 B1 19920429
DOCDB simple family (application)
US 15142188 A 19880104; AT 87116081 T 19871102; DE 3778668 T 19871102; DE 8700076 U 19870102; EP 87116081 A 19871102