| abstract |
A friction material made of a molded cork, a friction surface of which is covered with a liquid or semi-solid lubricant layer including a solid lubricant layer comprising a solid lubricant having a larger particle size and a solid lubricant having a smaller particle size and filling vacant spaces between the larger-sized solid lubricant in dense form, affords a long service life when used in a power controlling apparatus which can transmit power and/or change rotation speed by applying friction and using a friction material. |