PURPOSE: To prevent noise due to film vibration by placing opposite the forward ends of ribs projected on the inner surface of a case member to increase the surface rigidity.
CONSTITUTION: Ribs 43, 44 and 45, 46 are brought into contact with each other to form partition walls, so that an oil path 47 is formed on the outer peripheral side of a drive sprocket 18. Among the respective opposite surfaces of a front case 13 and a rear case 15, the portions positioned between the sprockets 18, 19 are provided with oil receiving ribs 48, 49 projected thereon, the forward ends of which are brought into contact with each other. Though vibration is caused by operation of a power transmission mechanism 20 in the driving condition, the oil receiving ribs 48, 49 placed opposite each other are formed on the inner surfaces of the front case 13 and the rear case 15 forming a chain room 14 to increase the surface rigidity. Accordingly, film vibration in the chain room 14 can be restrained to effectively prevent generation of noise.
OKADA MITSUHIKO
KUBO MASANORI
