(19)

(11)

EP 0 605 562 A1

(12)

(43) Date of publication: 13.07.1994 Bulletin 1994/28 (21) Application number: 92920320.0 (22) Date of filing: 16.09.1992

(51) International Patent Classification (IPC):  E21B 4/ 14( . ) E21B 21/ 10( . ) E21B 21/ 00( . ) E21B 21/ 14( . ) (86) International application number: PCT/US1992/007821 (87) International publication number: WO 1993/006334 (01.04.1993 Gazette 1993/09)

(84) Designated Contracting States: DE GB SE (30) Priority: 27.09.1991 US 19910766866 27.09.1991 US 19910766867 (71) Applicant: INGERSOLL-RAND COMPANY Woodcliff Lake New Jersey 07675-8738 (US)	(72) Inventors: LYON, Leland, H. Roanoke, VA 24019 (US) HINCK, Ernest, C. Roanoke, VA 24014 (US) (74) Representative: Feakins, Graham Allan, et al  RAWORTH, MOSS & COOK RAWORTH HOUSE 36 Sydenham Road Croydon, Surrey CRO 2EF Croydon, Surrey CRO 2EF (GB)