PULLEY FOR WIRE SAW

PROBLEM TO BE SOLVED: To reduce rotary resistance and to facilitate efficient cutting by a relatively small-sized unit by providing a cover at an outside of a pulley body, forming a space as an air reservoir between the cover and the body, and providing a supply port for supplying compressed air thereto. SOLUTION: Spaces 85 are formed between both sides 50a, 50b and inner surfaces of covers 60(A), 60(B) of a pulley body 50 to communicate with air supply ports 75. And, there is an interval 86 for passing a wire saw between annular parts 67 of both sides of the covers 60(A), 60(B), and a groove 51 of the body 50 is disposed at its center. Further, there is formed a smaller gap 89 than a width of the space 85 between an outer periphery of the body 50 and inward edges 68 of the covers 60(A), 60(B). This pulley P is fixed at its shaft 65 to a mounting frame 90 and used underwater. When compressed air is supplied from a compressor 100 on the ground to the ports 75, it is fully filled in the spaces 85 and gradually discharged from the gap 89.