LOOSENED AND ADJUSTED THE RESTORE AND DETENT BARS
I was able to achieve low resistance when I hand turned the print mechanism with all the detents holding their cams in the stopped position and the restore levers attempting to reset the Print Clutch Latch to stop any cams that were turning.
LATCHING AND RELEASING THE PRINT CAMS
The normal (rest) position of the Knockoff Armature Lever, which has a notch on the end, leaves the high point on one side of the notch underneath the Print Clutch Latch lever. The end of the Print Clutch Lever will bump into the Print Clutch Dog, stretching the spring and pivoting the dog so that its tooth is lifted out of the flutes of the Print Clutch Shaft.
When a magnet causes the Knockoff Armature Lever to pivot, the Print Clutch Latch tip is pulled into the lever notch du to the springs in the latch mechanism. As shown below, the Print Clutch Latch lever pulls off the end of the Print Clutch Dog, whose spring pivots it so the tooth slides into the next flute in the rotating Print Clutch Shaft turning inside the cam.
Putting this all together, the diagram below shows how all these parts cause the clutch to stop the Print Cam from rotating when the Knockoff Armature Lever is at rest. When the print magnet pulls on the linkage, the Knockoff Armature Lever causes the clutch to be released and the Print Cam begins rotating with the Print Shaft.
Since the print magnet will disengage quickly, the spring in the Knockoff Armature Lever is ready to pivot it back to its rest position. As soon as the Print Cam actuates the Print Clutch Restore Lever, the Print Clutch Latch is pushed back up and the Knockoff Armature Lever snaps back to its rest position.
The Print Latch Lever is up in the path of the Print Clutch Dog, allowing it to push the tooth out of the flutes and stop the cam at the end of one rotation. Meanwhile, before the cam comes to a rest, the high point of the cam pushed against the print wheel hanger and caused it to rotate to contact with the ribbon, paper and platen to print a character.
HAND TESTING OF THE PRINT MECHANISM
With the Print Restore Levers and the Print Clutch Detent levers in place, with the Print Clutch disks oriented to their rest positions, but the Knockoff Armature Levers not yet installed, I tested the mechanism by rotating it by hand.
Without the magnet assembly and its Knockoff Armature Levers in place, all the clutches are triggered by the Print Clutch Latches. The Print Clutch Latches on all of the columns will be pulled away from the Print Clutch Dog. The cams should all turn with the Print Clutch Shaft as a result.
About one quarter of the way around one rotation, the Print Clutch Restore levers will try to push the Print Clutch Latch back onto the Print Clutch Dog. Without the Armature Knockoff Lever in place, the latch will not activate and the dog tooth remains engaged; it would continue to turn after the first rotation. The only way to stop the rotation is to have the Print Clutch Latch hold the Print Clutch Dog out of the way, which requires the latch to be pushed against its spring either by hand or by the Armature Knockoff Lever.
When the disks reach about three quarters of a rotation, the high lobe pushes against the Print Wheel Hanger which would complete the printing action. I haven't installed the Print Wheel assembly with the hangers yet so the lobe isn't actually striking anything.
As mentioned above, all the clutches will trip again at the end of a rotation. However, I can hold up a few Print Clutch Latch levers by hand while rotating, which should cause the Print Clutch disks for those columns to stop turning when the restore lever does it thing. The Print Clutch Detent Lever should keep those cams resting quietly at their idle position.
The hand stop test worked, when the Print Clutch Latch levers are held in their idle position the associated print cams stop at the detent.
REINSTALL THE MAGNET UNIT WITH THE KNOCKOFF ARMATURE LEVERS
The magnet unit has the Knockoff Armature Levers which hold the Print Clutch Latch levers against their springs so the latch keeps the Print Clutch Dog from engaging its tooth into the Print Clutch Shaft flutes. The Print Clutch Latch sits on a high point on the Knockoff Armature Lever to accomplish this.
I slid the magnet unit into the frame and bolted it down.
HAND CYCLING TO VERIFY ALL CAMS STOP IN THEIR IDLE POSITION
Turning the print mechanism by hand should cause all Print Restore Levers to relatch the clutches on all 120 columns, thus the cams should all stop with the Print Clutch Detent levers in the notches of the cam. Pulling on a link for a column while turning the mechanism should release that one column and cause its print cam to make a single revolution before stopping in the rest position.
That worked perfectly and when I flicked one of the linkage levers in the magnet unit, its print cam performs one rotation. At this point I added the print magnet plate to the magnet unit and confirmed that the idle condition still keeps all the print clutch cams at their stopped detent position.
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| Magnet unit and print magnet plate installed |
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