(19)

(11)

EP 0 535 020 A1

(12)

(43) Date of publication: 07.04.1993 Bulletin 1993/14 (21) Application number: 91910524.0 (22) Date of filing: 07.06.1991

(51) International Patent Classification (IPC):  E01H 1/ 08( . ) (86) International application number: PCT/EP1991/001062 (87) International publication number: WO 1991/019047 (12.12.1991 Gazette 1991/28)

(84) Designated Contracting States: AT CH DE ES FR GB IT LI NL SE (30) Priority: 08.06.1990 GB 19900012786 (71) Applicant: SCHMIDT WINTERDIENST- UND KOMMUNALTECHNIK GmbH D-79837 St Blasien (DE)	(72) Inventors: BRADLEY, Richard, M., 30 Lavenham Court Petersborough, Cambs. PE2 PE2 0AT (GB) THOMPSON, Peter, G. Helpston, Petersborough PE6 7DQ (GB) (74) Representative: Grättinger, Günter  Grättinger & Partner Postfach 16 55 D-82306 Starnberg D-82306 Starnberg (DE)