| 摘要 |
To prevent premature wear and damage of elastic rings caused by fine grained soil, floating rings 22, 24 are supported by corresponding housings 20, 21 through associated elastic rings 23, 25. The elasticity of the elastic rings causes the floating rings 22, 24 to contact each other. When the housings rotate relative to each other, the floating rings 22, 24 slide with respect to each other. An elastic layer 28, 29 is arranged on a contact surface of a portion of a contact surface of each floating ring 22, 24 or a contact surface of each housing 20, 21 with respect to the corresponding elastic ring located closer to an opposing portion 22a, 24a of the floating ring 22, 24. |
