AE Type 24 Dial Disassembly

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This is the most common AE dial found on most phones using that dial. The AE 24A36 was an upgrade of the original AE 24 dial and from the AE notes, it seems the newer AE 24A36 dial used the red phenolic oblong disk to pulse the line. Seems the earlier, original AE 24 version did not have this disk and I have never seen one. The original dials were in use for 10 years (into the 1930's) and all original dial may have been replaced by the newer, quieter AE 24A36. The AE 24A36 was used in this topic.

During disassembly, removal of each part should be closely observed in that the dial does contain a few, thin washers which when covered with crud look like they are part of the dial. Upon cleaning, these washers will come free so their original location should be noted during disassembly. The images in this topic include these small washers, some as inserts because they were not found until cleaning the part on which they were mounted.

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This is the subject dial of this topic (NOTE: click on the inserted image to enlarge it and if that doesn't work, click on the attached image at the bottom of each post).



complete with a mounted number card holder. The back side clearly shows the red phenolic oblong pulse pawl.

The number card holder is not hard to remove but a bit tricky. This link will take you to the TCI library page showing the AE Co. instructions for card holder removal, and attachment.

This card holder information at that link is attached to this page as a PDF file.

The first step is to note the location and position of the red phenolic pulse pawl, upper pulse circuit main spring wing, the lower shunt circuit main spring wing, the pulse contacts (blue circle) and the direction of the pulse pawl with respect to the center of the main spring.



The pulse contacts are circled in yellow, the shunt contacts circled in blue and the direction of the red pulse pawl (the hole in the oblong disk line up with the center of the main spring post).



Applying the instructions from the link given above, a small, thin, flat bladed screwdriver is used to move the retaining wing to the left freeing the number card holder. As the card holder is lifted up from its retaining wing, the holder is lifted out of the metal dial slow (yellow line).



A slotted screw driver is used to remove the center screws holding the number card retention ring and the metal number plate to the dial mechanism.

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The finger wheel is then lifted off exposing the number plate and the two clips that hold the number plate to the dial case (red circles). Note that the finger wheel as shown looks like it is rotated 180 degrees. This the back of the finger wheel, flipped over, so the holes look wrong.



The next step is to use a tool that will grab onto each of the two hook clamps holding the number plate to the dial case. This is done by lifting the clamps up and into the center of the number plate freeing the number plate. Be careful and use a good tool to prevent scratching or cracking the number plate. I use a surgical steel instrument that has a 90 degree bend at the end to do this.



The the number plate removed, shown flipped over, the notch that fits around the finger wheel stop (blue line) and the two released number plate clamps (red circles) can be seen.



This image shows that part of the dial finger stop that acts as the dial stop (inside the red circle). This is the resting position of the dial.



Looking at this part of the dial from the side shows how all the parts fit together. There is a metal dialing pawl that is in contact with the main spring gear ratchet (blue circle). This pawl spring toward the center of the gear when removed and must be pulled away from the ratchet part of the gear to assemble it correctly.



At this point, the next step will be removal of the main spring from the pile up side. To do this, the finger stop side of the dial must be held in the palm of a hand (red circle part) with the center of the dial, the main spring shaft assemble plate, place tightly against the center of the palm of the hand (yellow circle part). Upon removal of the main spring, the center assembly, the yellow circle, will be loose and will slip out of the main spring tunnel. Unless pressure is placed on the yellow circle part holding it in, toward the dial case, removal of the main spring (a few steps below) will be impossible.

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Next step is to turn the dial over and begin by getting the leaf pileups out of the way. There are 2 screws on each side of the pileup as shown in the above image. The red circled screw will be loosened one turn and the blue circled screw will be removed.



Once the blue screws are removed and the red screws loosened on turn, both side of the pile up can be rotated up and out of the way (lift them up together, at the same time - there is a metal strap holding the two pile ups together which must not be bent).

Upon lifting the pile up out of the way as shown, the red screws are tightened to hold the pile up in that position giving full access to the remaining parts on the back side of the dial case. Put the two removed screws in a safe location so they will not get lost.



With that done, notice the position of the red phenolic oblong pawl and the two wings on the main spring assembly. The holes of the pawl line up with the center of the main spring shaft (red line), the pulse wing (the higher wing circled in blue) is on the governor side of the main spring shaft and the muting wing (the lower wing circled in green) is away from the governor.



Also notice the position of the lower spring retention ear (yellow circle), the slot in the top of the main spring shaft (blue circle) and the upper spring retention wire inside the main spring shaft slot (red line). These positions, when assembling the dial will put 1.25 to 1.5 turns of pretension into the main spring when the dial is at rest, the dial mechanism is at the dial stop.



Next, the pulse pawl is removed by placing a small, flat slotted screw driver to keep the dial worm gear from turning (red circle). Use a small wrench to turn the nut to the left, counter clockwise (blue circle) and when loose, remove the nut. Be careful not to loose the really small lock washer inside the nut, between the nut and the washer.

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After removing the nut, you will see the bottom of the nut is recessed (blue circle) to hold the lock washer to the pawl. The red phenolic oblong pulse pawl can then be lifted off. The bottom of the pawl is shown (red line) which was held in place on the pulsing shaft with a serrated nut (green circle).



Again, note the position of the lower spring wing, which of the 3 possible retention ears are being used (red arrow) and the top spring retention bar in the main spring shaft slot (blue circle).



The next step is main spring removal and to do that, the main spring assembly (#1) must be held tight against the dial case (green arrow direction). Also note the dial ratchet (#2) and the metal piece (#3) showing the end of the wing on the piece is bent 90 degrees away from the dial case.



Another view of this part of the dial shows the dial ratchet (blue circle), the mechanism at the dial stop (red circle) and the location of the unknown metal part (yellow circle). I am not sure what that component does in that I have worked on some AE dial that did not have this part, this one does.



Next thing is the removal of the main spring. This is done by pushing down of the top of the main spring, forcing it down the main spring shaft toward the dial case, and turning it to the left to allow the upper spring retention bar to become aligned with the slot in the main spring shaft. When this is done, lift up on the main spring and it will come loose from the shaft.

The inserted box in the above image shows the construction of the top of the main spring shaft. At the bottom of the slot (red line), a hole exists in the shaft to capture the main spring top retention bar.

The spring retention ear slips right out of the ear on the case used to hold the spring (blue line).

At this point, the main spring shaft and mechanism is loose in the dial case tunnel so carefully remove the case from the palm of you hand (the part may be in your palm is the shaft is not crudded up holding it in the tunnel).



After removal of the spring, the dial assembly can be pulled out of the main spring shaft tunnel (red line). The main spring gear will stay in place (blue arrow).

For this dial, I had to apply some force to remove the shaft from the tunnel. The oil had dried up turning it to crud holding the shaft inside the tunnel. If the crud does not exist, the shaft will fall out by way of gravity.

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The main spring shaft assembly, once removed (and you can see the crud on the shaft), is composed of a fiber washer (#1), the dialing ratchet wing (#2) and the unknown winged metal part (#3). There is a metal thrust washer under part #3 not seen in this photo.



A side view of the assembly shows the shaft (with its slotted top end), the fiber washer (#1), the end of the ratchet (#3) and the unknown winged part (#2). The direction of the bends on part #2 is noted for reassembly.

Just below part #2 you can see the silver colored thrust washer.



This is a top view of the main spring shaft with the fiber washer (#1) removed showing dialing ratchet (#3) and the winged part (#2).



The main spring shaft assembly consists of, from top to bottom on the shaft, the fiber washer (#1), The winged part (#2), the dial ratchet (#3) and the metal thrust washer (#4).



Next step is to remove the finger stop which acts as the dial stop and the axle bearing point for the pulsing shaft (red arrow). Simply use a suitable sized slotted screw driver to remove the two screws (blue circles) holding the finger stop to the dial case. Be careful to catch the nuts on the other side of the case (they are held within indented pockets on the pile up side of the dial case when screwed together). Place the two screws and nuts in a safe location so they don't get lost.



Removing the finger stop frees up removal of the main spring gear and the pulsing shaft (red arrow).

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Next step is to lift the main spring gear (yellow line) off of the main spring case tunnel and to remove the white fiber washer (blue line) between the gear and the dial case.



This image shows the main spring gear and fiber washer removed.



Next step is to turn the dial over and remove the pulse shaft assembly. Place a small, flat bladed screw driver into the pulse worm gear  (red circle) and use a wrench to turn the serrated nut counter clockwise (blue circle) to remove it.



Remove the nut from the shaft. The above image shows the bottom of the nut which is flat, not serrated.



With the nut removed, the shaft drops out of the dial case (blue line). Note the small washer (red circle) which can be removed for cleaning. In this image you can also see the difference between the pulse main spring gear (very dirty with crud packed into the depths of the gear teeth) and when cleaned (inserted box (yellow line). This gear required cleaning using a tooth brush and a wood round toothpick to scrub the dirt out of the gear teeth.



Last step is to remove the governor assembly. Start by using a 1/4" wrench to loosen the lock nut on the set screw (blue line) side of the governor assembly.

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Use a small flat bladed screwdriver to remove the set screw (blue circle).



Next, carefully remove the governor shaft (with fly wings and worm drive) out of the dial case.



Next, use a 1/4" wrench to remove the nut holding the governor raceway to the dial case.



With the raceway removed, note the axle bearing point inside the raceway, the only part of the governor raceway that should be lubricated during assembly (blue line).



That completes disassembly of the AE Type 24 dial. Lot of images and words so it seems like a major thing to do. Actually, with minimal experience, it takes less than 15 minutes to do this and in the end results in 15 parts and 2 washers being removed for cleaning (the 2 washers held tightly to the parts by crud but found during cleaning are noted with yellow lines above).

I use lacquer thinner, a tooth brush, a round tooth pick and a source of compressed air to quickly dry off the thinner.

To put it back together, another topic showing proper lubrication and assembly will be posted.

The hardest to do is the first dial, have to go slow, observe and learn. After a couple of dials, I can do this in 15 minutes, with another 5 minutes for parts cleaning and another 15 minutes for lubrication and assembly. Remember, these are complex mechanisms designed by highly competent engineers to that they can be assembled, many a day by a worker with no knowledge of either.

Any questions, or found errors in everything above, will be appreciated.

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Once the dial is completely disassembled, it is highly suggested that any bends in the Governor Shaft Fly Wings be removed. It's a lot easier to straighten them when the shaft is out of the governor assembly.



The left two images are the same of a very dirty governor worm drive in a crudded up dial. The wings have been bent (yellow circle) in the field to put less pressure on the raceway by the brake pads, something that was done to speed up a dial slowed by crud build up (green circle).

Since the dial was taken apart to be thoroughly cleaned and properly lubricated on re-assembly, the bend fly wings will not be putting enough pressure on the raceway and the dial speed will be too fast.

While the wings will need small adjustments once the dial is back together, it is easier to make those adjustments if you start out with fairly straight wings. The amount of adjustment can only be determined after the dial is put back together and the cleaned/lubricated dial speed is determined.

The second image from the right shows fly wings that have not been field adjusted (blue circle).

The image on the right shows the shaft and fly wings after being removed from the governor assembly (red circle).

If the bent wings are made to look very close to the wings in the red circle, adjusting the speed of the cleaned dial will be much easier than trying to do so with already bent up wings.

The flat section of a small needle nose pliers (yellow circle - the area closest to the pliers hinge)



can be used to straighten the wings without damaging the flat metal wings.

Working with the wings, once assembled, to adjust the dial speed is covered in this topic reply:

https://www.classicrotaryphones.com/forum/index.php?topic=28413.msg271931#msg271931