Adjusting the rotate character selection on the 1053 - part 2

 RESTORING ADJUSTMENT OF CYCLE CLUTCH TO SELECT CAM SHAFT

I spent a few hours doing research into the structure and adjustment principles of the cycle clutch to get the select cam shaft in the right orientation to the idle position of the clutch. What I learned, however, was that the clutch and machine were probably already correctly adjusted. Instead, the incorrect selector latch restore adjustment was a measurement error due to an undocumented subtlety when hand-cycling.

The design of the cycle clutch is to have a rubber bumper jam the turning clutch shell which unwinds the spring because its other end is fixed to the always turning operational shaft. The clutch would come to a stop and its momentum would carry it up to and past the idle position slightly, IBM calls this action overthrow. 

The driving force ends at about 170-175 degrees of rotation and momentum takes it to the 180 degree stopping point. When the clutch reaches the idle position on its way to its overthrow point, the check pawl drops into a notch. This will block the clutch from turning backwards as it rebounds off of Overthrow Stop lugs that prevent the momentum from moving the clutch too far forward. 

Check pawl on far left of print cycle shaft, clutch on right

Overthrow stop adjustments

Clutch assembly

What this means for me is that when you hand cycle the machine the momentum does not exist. The clutch does not continue to the full rest position and the check pawl does not yet drop into its notch. Therefore the cams for the selection bail are not at their final low point.

This is why the selection levers are not restoring under the bottom of the bail. They would if the print cycle took place under motor power, but do not while hand cycling. The adjustment manuals do NOT mention this clearly. 

Therefore I will have to set up the cycle clutch as it was, so that it works properly under power. I can test the selection lever restoration under the bail by tripping the clutch after it stops and moving the shaft forward just until the check pawl drops into place. 

The process is:

• Move the shaft to get the check pawl in its notch and the clutch at its rest position
• Mount the degree wheel on the print shaft and set it to 0 degrees.  
• Select a zero tilt, -5 rotate character as this produces the highest resistance to the clutch. 
• Continue cranking the clutch until it is just beginning to slip
• Note the degree marking where this occurred. It should be 170 to 175 degrees.
• Then I will turn further until the check pawl slips into its notch. 

The adjustment is to loosen the screw locking the collar on the clutch, as well as the two Overthrow Stop screws, then rotate the collar until I achieve the above point of slippage.

Next the Overthrow Stop latches must be set. The process is:

• Have the cycle clutch in its latched idle position
• Ensure check pawl is in the notch
• Turn slightly backwards to hold firmly against check pawl
• Adjust Overthrow Stop latches to allow only .007" to .015" of overthrow movement
• Perform a second time to set the other Overthrow Stop latch

I again encountered a phenomenon with IBM documentation that is all too common. The documentation is technically accurate but not helpful. In this case it was the description of where to measure the .007 - 0.015" overthrow. Below is the IBM diagram from the manual.

Color marks are my additions

This diagram shows a space of .007 to .015" but what does it reference? The cutout on the right with the red arrow implies that there is a gap to the upper edge of a cutout. First problem - my clutch does not have any cutouts on the right. It does instead have a gap, show as the green rectangle, on the left but only on one side. It is only exposed on every other print cycle since the clutch rotates 180 degrees per cycle.

I discovered that the correct place to measure that gap is down out of sight, where the blue arrow is pointing. the other end of the plastic Cycle Clutch Collar arc from where the measurement was written is the place where that arc bumps into the ledge of the metal Cycle Clutch Sleeve, see the circled area below.

Once I figured that out, I could get the cycle clutch dialed in so that it stopped properly with the check pawl in its notch, and began to slip at 170 degrees into the cycle when powering a tilt 0 rotate -5 character. These adjustments were completed and the operation of the print cycle clutch was verified. 

GOING BACK TO FIX UP THE PRINT SHAFT ALIGNMENT

I had shifted the select cam shaft relative to the idle position. Since that shaft is what drives the gears to turn the print shaft through the carrier, this adjustment needed to be redone to get the key slot pointing at the small hole again. With that complete, I could move forward on the remaining adjustments for rotate selection. 

 -5 ROTATE SELECTION LATCH ADJUSTMENT

Most of the selection mechanism works by the lever tips fitting under the bail and being pulled down as the cams move the bail downwards. However, the R5 selector magnet operates the -5 Rotate Selection Latch which operates differently. That lever will move upwards riding on a cam if it is activated. 

A Stop Bail blocks that movement if the magnet was not activated so that the lever does not move down the cam surface. When the magnet activates, the Stop Bail pulls out of the way permitting the lever to be pulled upwards and its arm ride down to the low point of the cam 

The adjustment insures that Stop Bail can move over the Stop Screw when unselected and that there is no drag stopping it from pulling off the head of the Stop Screw when activated by the R5 selection magnet. 

Bail Stop red, Stop Screw green, adjustment Blue

ROTATE ARM VERTICAL ADJUSTMENT

This adjustment adjusts the rotate pivot arm so that it is vertical when the selection mechanism wants the ball at its unrotated (home) column. The instructions sound simple. They mention that I could use an IBM tool called the Hooverometer to check that the scribed line is parallel to frame, or of course just use any measuring device to see that the top and bottom of the scribed line is the same distance from the frame. 

scribed line

x

Hooverometer

This sounds simple but on the actual printer, there is no section of the power frame next to the scribed line and other parts block the view. At best you have to mentally project a view of the power frame to figure out where it would be if next to the pivot arm, then assess the distance to the scribed line at two points. 

What I was finally able to do was find an inner surface that was flat and parallel to the side of the power frame, so that I could use the Hooverometer to check the distance from there to the top and bottom of the scribed line. 

Flat surface pointed to by green arrows

I verified that this was set to be parallel to the power frame within the precision of the measurement I took. Since this is an initial setting that will be refined later in the procedure, I marked this as complete.