| 摘要 |
PURPOSE:To aim at keeping off the admission of foreign substances into the inside of a drum and checking a temperature rise inside the drum, by installing a ventilating hole in a backing plate and also installing a cover to be opened at a setting temperature having one end freed to this hole but the other end locked to the plate. CONSTITUTION:A peripheral edge part 1b of a backing plate 1 is fitted in a groove 2a of the peripheral edge part of a drum 2 with some play, and the outer circumference of the drum 2 is covered by a dust cover 1a. An axle tube 3 is locked on the outer surface of the said plate 1, while an axle 4 is locked on the inner circumference of the drum 2 by piercing through a vent hole 1c of the plate 1. Then, brake shoes 5 and 6 are installed in an empty space formed by both the plate 1 and the drum 2. At the said plate 1, there are provided with plural ventilating holes 10, then a cover 11 having one end freed to these holes but the other end locked to the outer surface of the plate 1 is installed likewise. And, the cover 11 is made up of a bimetal member or the like to be opened outward the plate 1 when temperature comes to the setting one. |
