To remarkably reduce the generated noise by installing a bumper formed with such a size that before another part of a trolley touches, it comes into contact with the trolley to absorb most of collision energy on a part of the trolley, that is, a part of the trolley that is normally out of contact therewith.

When one carrier 34 comes into contact with another carrier 34, a front wall 16 of a bumper 10 on the moving side trolleys 40, 42 comes into contact with the front wall 16 of the bumper 10 on the stationary trolleys 42, 40. Both bumpers 10 are compressed by the force of a carrier 34 on the side where a contact wall 64 collides with a blade part 62 to stop the carrier 34. The bumper 10 is formed by a urethane resin so that the noise when both bumpers 10 collide with each other is made smaller than that when metal bodies collide with each other. Instead of converting the collision energy to a sound wave, the collision energy is absorbed by elastic deformation of the urethane resin.