A lead propelling mechanism for a mechanical pencil includes a lead chuck, a ring fitted loosely about the chuck for tightening its head, a sleeve having a front end contacting the ring, and an elastic member having a front end bearing on the front end of the sleeve and a rear end held by a shoulder formed on the outer surface of the chuck adjacent to its rear end. The mechanism is very easy to assemble and join to a lead holding tube in the pencil. The rear end of the elastic member bears against an adjacent end of the tube to urge the ring to tighten the head of the chuck, when the chuck is inserted into the tube.
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