(19)

(11)

EP 0 255 536 A1

(12)

(43) Date of publication: 10.02.1988 Bulletin 1988/06 (21) Application number: 87900905.0 (22) Date of filing: 14.01.1987

(51) International Patent Classification (IPC):  E21B( . ) E21B 4/ 14( . ) E21B 17/ 04( . ) E21B 17/ 042( . ) (86) International application number: PCT/SE1987/000009 (87) International publication number: WO 1987/004487 (30.07.1987 Gazette 1987/17)

(84) Designated Contracting States: AT CH DE FR GB IT LI (30) Priority: 17.01.1986 SE 19860000199 (71) Applicant: LÖVAB LÖF OCH ÖSTLUND AB S-686 00 Sunne (SE)	(72) Inventor: LÖF, Uno S-686 00 Sunne (SE) (74) Representative: Lautmann, Kurt O.  KURT LAUTMANNS PATENTBYRA AB Box 245 S-691 25 Karlskoga S-691 25 Karlskoga (SE)