PURPOSE: To protect a roller guide surface and prevent the generation of metal powder and a noise by separating both rollers into the first and second rollers respectively capable of independent rotation about a pin, and providing a groove at the opposite sides of the guide surfaces of a guide hole in contact with the rollers.
CONSTITUTION: A roller at one side and inserted in the first guide hole 5 of the first arm 1 is separated into the first and second rollers 11a and 11b, and a roller at the other side and inserted in the second guide hole 6 of the second arm 2 is also separated into the first and second rollers 13a and 13b. In addition, each of the rollers 11a, 11b, 13a and 13b is so retained about a pin 9 as to be capable of independent rotation via respective bearings 10a, 10b, 12a and 12b. Grooves 5x and 5y are formed on the opposite sides of the upper and lower side guide surfaces 5a and 5b of the first guide hole 5. Also, grooves are formed on the opposite sides of the right and left guide surfaces of the second guide hole 6. According to the aforesaid construction, it becomes possible to prevent the contact surfaces of the rollers from moving from one place to another with a large impact force.
AKAMATSU OSAMU
ENOKIHATA NORIO
