ROTATION DEVICE FOR CONSTRUCTION MACHINE

摘要

A floating seal (23) is provided between a mounting bracket (12) fixed to a side frame (6) and a roller (15) rotatable with respect to this mounting bracket (12), and lubricant oil (L) collected in the roller (15) is sealed by this floating seal (23). On the other hand, an air permeable plug (31) provided with an air permeable member (34) made of a porous material of interconnected cells is provided on a lid member (17) of the roller (15), air and/or water vapor is made to flow between the inside and the outside of the roller (15) and flow of lubricant oil (L) and/or rainwater and dusts is prevented by the air permeable member (34) of the air permeable plug (31). As a result, the pressure of the inside and the pressure of the outside of the roller (15) can be made equal all the time.