AGENCEMENT D'ETANCHEITE POUR UN BOUT D'ARBRE

Cette invention concerne un dispositif à joint d'étanchéité à lèvre (25) pouvant venir pincer un bout d'arbre (15) placé derrière un bouchon (26). Quand le bouchon (26) est installé et couvre le bout d'arbre en fermant un carter (8), il presse sur un bourrelet de butée (23) du joint (20) et repousse la lèvre (25) vers l'extérieur, si bien que la rotation du bout d'arbre (15) n'use pas le joint. Quand il est retiré, le carter (8) est ouvert mais la lèvre (25) pince le bout d'arbre et rétablit l'étanchéité.Cet agencement est utile notamment aux bouts d'arbre (15) munis d'une prise d'outil pour imposer une rotation manuelle à une machine tournante pendant une période d'entretien à des fins d'inspection, le bout d'arbre (15) étant entraîné pendant le service normal de la machine. The shaft (15), connected by bevel gears to a main compressor shaft and rotated by a manually-operated key or machine, has its end located behind a plug (26) fitting an aperture (17) in the turbine housing (16). The end of the shaft is located in a seal (20) fitted between it and the housing and having an elastic lip (25) pressed against the shaft. The plug has a projection which acts as a pusher (27) which lifts the elastic lip from the shaft end when the plug is in place. In a variant of the design the seal is in the shape of a flat disc. The seal can have a retaining strip (21) which fits in a housing recess and a thrust collar (23) which is pivoted to it and faces the plug. The seal lip is conical in shape and connected to the collar. It is made from a supple elastomer material such as PTFE (polytetrafluoroethylene), and is reinforced by a metal spring (33).