PURPOSE: To have easy replacement of feed roller with simple construction by furnishing a pushing member, which shall push the feed roller, pivoted by the feed roller supporting part, so as to put it in engagement with the shaft end of the drive shaft.

CONSTITUTION: Feed roller supporting part 6 is provided on the extension line of the drive shaft 3, and a feed roller 7 is furnished pivoted by this supporting part 6 and in engagement with the end of the shaft 3 separably. Further, a compression coil spring 13 is installed to press the roller 7 so as to be in engagement with the end of the shaft 3. A circle lip 11 is fitted in a circumferential groove provided in the shaft 8 for the roller 7, and a bushing 12 is fitted from the other end of the shaft 8. After fitting loosely a spring 13 on the shaft 8 and bushing 12, the other end of the shaft 8 is fitted in the bearing 6 installed in the framing 1 in the condition that the spring 13 is compressed, and then one of the ends of the shaft 8 is fitted in a sleeve part 4 of the shaft 3 as well as the notch 9 provided in the shaft 8 is put in engagement with a pin 5 installed in the sleeve 4, and now it is ready for mounting on the framing 1 in the condition that the roller 7 is coupled with the shaft 3.