(19)

(11)

EP 0 898 739 A1

(12)

(43) Date of publication: 03.03.1999 Bulletin 1999/09 (21) Application number: 97903042.0 (22) Date of filing: 22.01.1997

(51) International Patent Classification (IPC):  G05D 16/ 16( . ) (86) International application number: PCT/US1997/000944 (87) International publication number: WO 1997/041496 (06.11.1997 Gazette 1997/47)

(84) Designated Contracting States: AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 29.04.1996 US 19960642024 (71) Applicant: Dresser Industries Inc. Dallas, Texas 75201 (US)	(72) Inventors: THEODOS, Michael, Andrew Alexandria, LA 71301 (US) DANZY, Roger, Dale Pineville, LA 71360 (US) (74) Representative: Reichel, Wolfgang, Dipl.-Ing., et al  Reichel und Reichel Parkstrasse 13 60322 Frankfurt 60322 Frankfurt (DE)