| 摘要 |
PURPOSE: To rotate a feed wheel in either of the forward and reverse directions by only a simple operation of rotating an open cam by a method wherein a drive pawl and an engaging pawl are pushed out by the crest parts of the rotatable open cam having a diameter larger than that of the teeth part of a ratchet wheel outward in the radial direction of the ratchet wheel. CONSTITUTION: An open cam 16 is rotatably mounted on a rotating shaft 2 and has crest parts 16a and 16a having a diameter larger than that of a ratchet wheel 13. The cam 16 is positioned on a side, where a pin 14b of a drive pawl 14 and a pint 15b of an engaging pawl 15 are projected, and the crest parts 16a and 16a of the cam 16 are also respectively positioned in the vicinities of the pins 14b and 15b. Accordingly, when the cam 16 is rotated, the crest parts 16a and 16a of the cam 16 push out the pawls 14 and 15 outward in the radial direction of the ratchet wheel 13 against the biasing force of the pawls 14 and 15 to release the biting of the teeth part of the wheel 13 with the pawls 14 and 15 and the wheel 13 is put in a state that it is opened. A feed wheel 21 is freely rotated in the forward and reverse directions. |
