(19)

(11)

EP 0 138 866 A1

(12)

(43) Date of publication: 02.05.1985 Bulletin 1985/18 (21) Application number: 84901053.0 (22) Date of filing: 14.03.1984

(51) International Patent Classification (IPC):  E21D 11/ 00( . ) E21D 21/ 00( . ) E21D 20/ 02( . ) (86) International application number: PCT/AU1984/000042 (87) International publication number: WO 1984/003734 (27.09.1984 Gazette 1984/23)

(84) Designated Contracting States: AT BE CH DE FR GB LI NL SE (30) Priority: 14.03.1983 AU 19830008432 (71) Applicants: TUCKER, Michael Charles Brisbane, QLD 4061 (AU) GEARHART AUSTRALIA LIMITED Brisbane, QLD 4000 (AU)	(72) Inventors: TUCKER, Michael Charles Brisbane, QLD 4061 (AU) GEARHART AUSTRALIA LIMITED Brisbane, QLD 4000 (AU)