PURPOSE: To obtain a movement transfer mechanism excallent in durability without using a large number of pulleys by transferring the turning of a sieve having a large diametral sieve to an excavation dust processing device through a small diametral sieve turning therewith, a movable sieve and a transferring member.

CONSTITUTION: When a certain amount of rotation of a large diametral sieve 31 is made by pulling a main wire 7, a small diametral sieve 32 is turned therewith. After that, the turning of the small diametral sieve 32 is transferred to a movable sieve 33 by a complementary wire 5, and the movable sieve 33 moves with a transferring member 4 capable of moving within a specific area. Then, when the small diametral sieve 32 rolls in the complementary wire 5, the transferring member 4 is displaced in the direction approached to the small diametral sieve 32, and the displacement is transferred to an excavation dust processing device 6. In that mechanism, force pulling the main wire 7 is magnified at a required magnification to transfer it to the excavation dust processing device 6 by properly setting the magnification of the diameter of the large diametral sieve 31 against the diameter of the small diametral sieve 32.