Disassembling 1132 printer mechanism to free up thousands of stuck parts

PRINTING MECHANISM IN 1132 PRINTER

The printer has 120 wheels suspended from the top on a pivot rod. The wheels have teeth around the edge that engage with a gear the entire line width, below the print wheel. That wide gear spins all the print wheels continuously at 112.5 RPM. The print wheel has 48 characters formed on its rim spaced evenly around the wheel. 

A cam on another mechanism will bump into the left side of the print wheel hanger, so that it pivots to the right and strikes the paper on the platen. A spring pulls the hanger back to its neutral position as soon as the cam lobe rotates past. 

A spinning clutch shaft to the left of the print wheels has 18 flutes on it. Suspended around the shaft is the print cam with its clutch mechanism that holds a tooth (print cam dog) away from the spinning clutch shaft. A print cam detent lever fits into a notch in the cam to hold it from rotating. The cam has one lobe on it, the lobe will eventually push a print wheel to type a character.

In the diagram above you see the print cam sitting in its latched position. The Print Cam Detent is engaged in a notch near the top of the cam which holds it so its lobe is near the bottom - hidden behind the latch mechanisms in the diagram.

The Print Clutch lever is holding the Print Cam Dog outward, against its return spring, so that the tooth on the Print Cam Dog is not in the path of the flutes on that Clutch Shaft rotating inside the cam. The Print Clutch lever is held in this position where it blocks the Print Cam Dog movement, by the Armature Knockoff Lever whose rightmost tine presses up to hold the Print Clutch in that position. 

When it is time to print a character, a Print Magnet is activated, attracting its Armature. The Armature pulls on a Link which tilts the Armature Knockoff Lever, causing the Print Clutch to fall into the space between the two tines of the Armature Knockoff Lever. 

Because the Print Clutch Latch has fallen off the Print Clutch Dog, its spring pulls it down and the tooth on it engages with a flute of the Clutch Shaft. The cam begins rotating clockwise. When it is about 3/4 around the lobe strikes the print wheel hanger to push the print wheel into the platen. 

Meanwhile, the lobe of the cam has moved the Restore Lever which pushes the Armature Knockoff Lever back into position and sets up the Print Clutch Latch to hold the Print Clutch Dog tooth out of the flutes. This stops the cam thus we get just one rotation and one swing of the Print Wheel into the platen. 

 

All of these levers and springs must move freely. The Print Clutch Dog and the cams must move freely. So to the print wheel and any other parts that contribute to printing a character in a column. For each of the 120 print columns, there are 18 parts involved, most of which must not be glued in place. 

The oils and grease used by IBM in the 1960s breaks down with time, as well as absorbing dust in the air. The result is a sludge or glue that forms keeping every moving part from moving. It keeps every spring from compressing and extending. It keeps every rotating part from rotating. 

The restoration requires me to free up all these tiny parts for all 120 columns - a total of 2,160 items I have to free of old lubricant and get moving properly. I use an ultrafine clock oil (Nye oil) that will seep in between the sludgy old lubricant and the metal surfaces. By carefully manipulating every part, I can work it free. 

To make this happen, I have to partially disassemble the printer mechanism. The parts from the Print Magnet up to the Armature Knockoff Lever are in a removable Magnet Assembly. This in turn has a plate with all the Print Magnets that can be removed from the larger Magnet Assembly. 

I have the Magnet Assembly out of a workbench and the plate with the Print Magnets is sitting by the printer read for me to restore those parts. 

Magnet Assembly minus Print Magnet plate

Plate with Print Magnets

The Print Wheels with their hangers and the remaining clutch parts are still in the machine where I can access them to some degree. 

In the last picture we are looking up towards the clutch and its parts, with the print wheel parts farther behind that. I will first work on the Magnet Assembly and Print Magnets.