| 摘要 |
A needle positioning mechanism for a sewing machine in which the needle driving shaft of the sewing head mounts a pair of pulley wheels and a lock wheel. The pulley wheels are mounted with overriding clutches for independently driving the shaft; one pulley wheel connected to the main motor of the machine and the other to an auxillary motor having juxtaposed switches in its circuit; one normally open and the other normally closed. A lock arm having a detent projection at one end is movable by a solanoid energized by an operator into contact with the lock wheel which is provided with at least one detent recess. In its movement against the lock wheel, the lock arm closes the normally open switch as it contacts the surface of the lock wheel, to activate the auxillary motor, and then closes the normally open switch to deactivate the auxillary motor as its projection engages within the detent recess of the lock wheel.
|
