Arm operating device in automatic operating machine

Claim 1

An arm or wrist operating device for an automatic operating machine, said operating device including a supporting arm, a bending arm which is rotatably supported on said supporting arm, and drive means for turning said bending arm, wherein the drive means incorporates a driving wheel, a driven wheel, first and second wrapping power transmission belts laid over said driving wheel and said driven wheel respectively, first and second transmission rods, one end of said first wrapping power transmission belt being coupled through said first transmission rod to one end of said second wrapping power transmission belt, and the other end of said first wrapping power transmission belt being coupled through said second transmission rod and a tension device to the other end of said second wrapping power transmission belt, said tension device incorporating a connecting rod, one end of which is connected to the second transmission belt and the other end of which is accommodated in a hollow end of the second transmission rod and is coupled thereto by a spring dashpot assembly, and a guide supporting said second transmission rod for sliding movement, said guide being located on the inner wall of said supporting arm in such a manner that the centers of coupling pins adapted to couple the wrapping connector power transmission belts to said second transmission rod are positioned inwardly of a line tangent to the minimum pitch circles of said wheel, each said wrapping power transmission belt having slack adjusting means and being made as short as possible according to a predetermined rotational operation range.