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WE #9 dial speed adjustment (also applies to #6 & #7 dials)

Started by TelePlay, June 22, 2022, 07:16:13 PM

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It's well known that necessity is the mother of invention. Necessity is also the force behind exploration and discovery.
Started to work on a 1965 WE 500 that was fully operational as found. Only problem was the dial. It has a #9C dial that was testing at 8.8 PPS.

01 9C dial.jpg

WE #9 dials were the last type designed by Western Electric. They were cheap throw away dials. If they were not up to spec, the dial was replaced with a brand new one and the old one tossed in the trash. The dial was not made to be serviced. Initially, the #9 dials had metal gears which were later replaced with plastic gears.

The #9 gear train was riveted together making it impossible to take it apart for proper cleaning and the governor was closed faced in that the governor tension spring could not be removed, as could be done with the open faced #6 and #7 dial governors, to adjust the dial speed.
Since 8.8 PPS was not acceptable, I first tried cleaning the dial gears and bearing points with a spray degreaser and applied fresh oil. This had no affect on the slow dial speed. The only option was to adjust the tension spring, in this case, add more tension to keep the governor brakes from contacting the governor race as easily and thereby increase the dial speed.

All #6, #7 and #9 dial were equipped with a plastic cover over the gear train assembly to keep dust and dirt out. These covers were removed prior to creating the following images. This #9C dial is dated 1973 so it was not the dial that originally came with the phone.

This image shows the main features of the #9 dial, the riveted gear train, the closed faced governor and the 3 large openings in the governor face.

02 9C Dial Annotated.jpg

For comparison, this is a #7 dial showing the 3 screws holding the gear train together (red circles), the open faced governor, the governor tension spring and the two hooks on the spring attached to the governor wings, the brakes.

03 7C Explanation Annotated.jpg

The tension spring is easily removed by unhooking each end from the wings and then adjusting the coiled spring to increase or decrease the trans-lateral tension to increase or decrease the dial speed respectively. This is a "side by side" comparison of the #7 to a #9 dial governors.

04 7C and 9C Comparison Annotated.jpg

This shows the main points of the #9 dial, the rivets, the closed face and the large holes in the face.

05 9C Explanation Annotated.jpg

This close up of the governor shows the tension spring hooked onto one of the two governor wings/brakes (blue circle). To adjust the dial speed, one of the hooks is removed from the wing with a fine tweezers, raised up through the access hole and adjusted. After adjustment, it is placed back into the governor and attached to the wing and the dial speed tested to check the results of the adjustment. If not within spec, close to 10 PPS, the hook is removed and re-adjusted, re-attached and re-tested. Repeat until the dial speed is acceptable, close to 10 PPS. Only one side of the spring needs to be adjusted at one time since the tension is trans-lateral, adjustment of one hook end affects both wings equally.

06 9C Governor Adjustment Annotated.jpg

Give that, I've found that the best way to adjust the tension in the coiled spring is to remove it from the closed faced governor. When I first wrote this topic, I was not aware that the spring could be fully removed from the governor case using the same method as one removes a key from a split key ring. This was added in Reply #7 below but the image, with annotations, is inserted here to show another way, what I think is a much better way, to work on the spring's tension.


This is what the governor tension spring looks like when completely removed from a #6 or #7 dial governor.

07 Governor Tension Spring Annotated.jpg

In a side view, the hook in the top image is as removed. The bottom image has been manipulated to show how the hook is adjusted. Once the hook is detached and lifted up and out of the governor, hold the straight part leading to the hook with a forceps. Use a fine nosed needle nose pliers to grab the hook and SLIGHTLY bend it inward or outward. This tension spring is made from spring steel so it is impossible to see how much bend is being put into or taken out of the hook. As such, it is better to go slowly, use minimal bending pressure, to not over-bend the hook. Several small bends are better than one large one since the affect on dial speed of any amount of bend is not known until the spring is re-attached and the dial speed re-tested.

08 Tension Spring Hook Adjustment Annotated.jpg

If the coiled spring is fully removed from the governor case, the tension can be adjusted by bending the ends as stated or by increasing or decreasing the coil of the spring. Making the coil smaller will increase tension (same result as bending a hook inward, shortens the distance between both hooks and increases tension, or speeds up the dial) or making the coil larger will decrease tension (same result as bending a hook outward, lengthens the distance between both hooks and decreased tension, or slows down the dial). When bending the coil to make it larger or smaller, again, it is spring steel and the amount of adjustment put into or taken out of the coil will not be seen or known until the spring is re-installed and the dial speed tested.

Using the "left inside" or "fully removed" approach can be used. This is how the dial speed is adjusted. The center image is assumed to be at 10 PPS. The red lines just touch the outside edge of the hook in this image.

The top image shows the hooks (yellow circles) bent out to reduce the tension on the governor wings, the hooks are slightly past the red line. This will slow the dial down.

The bottom image shows the hooks (green circles) bent in to increase the tension on the governor wings, the hooks are slightly inside the red line. This will speed the dial up.

This distance of hook to hook can be changed by bending the hooks slightly or adjusting the size of the coil itself.

09 Spring Tension Adjustment Example.jpg

In my first attempt, I slightly bent one hook inward and the dial speed of this yellow phone subject dial increased from 8.8 PPS to 10.6 PPS. I left it at 10.6 PPS in that a dial may slow down over time so it is better to have a dial testing a bit faster than 10 PPS than slower, call it a built in dust/dirt/age tolerance. The Break/Make ratio of this dial was 61/39 so with the speed adjustment, this very nice yellow WE 500 is good to go.


Obviously, this process of tension spring bending to adjust dial speed also applies to WE #6 and #7 dials except that with those dials, the spring can be removed from the governor which makes it a lot easier to bend the spring.


Great work, thanks for detailing, typing it all out and for the great illustration photos.


As these dials not seen so much in my and other parts of the world, could I please ask for images of the other side, if poss, just to help with dial recognition when still on phone.

Many thanks.

A collector of  'Monochrome Phones with Sepia Tones'   ...and a Duck!
Vintage Phones - 10% man made, 90% Tribble


This is the front view as it would be seen when looking at the phone but unfortunately, there is no way of determining if it is a #7 or #9 dial without opening up the phone.

With a good ear and a lot of dial experience, it may be possible to know which by listening to it, something my old ears can't do.

#6 dials were not used with 500s, just 5302s and 302s IIRC.


you can tell by looking under the finger stop  there is a zinc casting support on the #7 but not on the #9


Quote from: rdelius on June 23, 2022, 10:10:16 AMyou can tell by looking under the finger stop  there is a zinc casting support on the #7 but not on the #9

Robby, you are correct.

I remember seeing that post many times and not seen it other times but never paid attention as to why it was or wasn't there.

As you said, the #7 has the support, the #9 doesn't. That makes it quite easy to know which dial it is before buying.

And, the rectangular hole in the bezel is wider for a #7 dial to make room for the support while the #9 bezel has a thinner rectangular hole, no support.


Well, I was a bit incorrect, didn't completely understand the #9 dial, when I started this topic.

The governor tension spring on a #9 dial can be removed, taken out of the closed faced governor case.

Was working on a stubborn dial when I discovered the spring can be released from the governor case the same way a key is taken off of a key ring, and put back on.

It's a bit more time consuming but a lot easier to adjust the spring once it is out of the governor case.

Not that anyone is refurbishing their own dials anymore, but if they are or want to try, removal is a better way of working on a #9 spring.


Quote from: rdelius on June 23, 2022, 10:10:16 AMyou can tell by looking under the finger stop  there is a zinc casting support on the #7 but not on the #9

Cleaning a #7C that had it's lubrication turn to something close to axle grease, that thick and sticky.

Remembered to take pictures of the finger stop support post.