Replacing/repairing early tremulant run motors?

[David Anderson]

I don't get repair requests on very early Hammonds that often, but today, I was asked to look at a "B-3" that turned out to be a 1936 Model A with a SN under 2000.

Bypassing and disconnecting the rotten cabling and going straight to the line panel, I got the generator started, but the run motor's windings are open.

There are reports that the motor windings usually open up where they connect to the lead-out wires, so I suppose I could attempt to open up the motor and reconnect them. How bad a job is that?

I believe it's also true that the main difference in pre and post WWII run motors is the tremulant gear. How tricky is it to remove the scanner gear from a later run motor and install a tremulant gear?

[tpappano]

I'm glad you brought this up, I have the exact same issue with my “new” BC. As I understand so far, the gear is a press fit and must be pulled. I'm curious to know what you guys are using for a gear puller. I'm coming to the conclusion that I will need to custom fabricate one. I have two late model motors arriving tomorrow with which to swap parts...

edit:
Another small issue is that the tremulant mounts to the ends of extra long screws inserted from the flywheel side of the motor. The screws on a scanner style motor are too short, so it looks to me that the flywheel has to also be pulled so the longer screws can be swapped.

[Frankquip]

I have s/n 346 that had an open winding, I used a later model field but reused all the original armature and mounting hardware. I had to remove the gear to disassemble then replace it afterwards. Measure the distance that its pressed on so when you replace it you will have it in the same position. I used a fork style puller from a clock maker. I have not had any time to disassemble the early field to diagnose because it is encapsulated in a copper shield that is soldered together.
Good Luck and thanks for maintaining the original configuration.

[tpappano]

Do you have any link or other info on the puller? I tried using my drill press as a makeshift arbor press but that little sucker would not budge!

[tiredoldgeezer]

What worried me about a similar deal was that even were the gear to be gone, I still had an "open shaft" on that back side which kinda bugged me. I mean, it's not really open, but it does kinda look like something could get down in there -- and if it's possible, that's the first place it'll happen.

So, I took a deep breath and laid down a bunch of masking tape and them some more tape, sticky side up. Then I <gulp> hit it with a Dremel and cut the shaft. Dressed it up a bit.
Looked very clean.

I soaked a little cotton in Hammond oil and packed it (ever so lightly) around the shaft.
Never had any trouble. Started and ran great. Cotton never fell out.
Maybe I got lucky. Maybe that's a bit drastic. But years later, it still looks factory.

Wouldn't blame a guy for not undergoing such an amputation, but it's an option that worked for me.

[Frankquip]

You may have to heat up the gear

[tpappano]

Thanks, your tool is essentially what I imagined might be needed, I will build one!

[David Anderson]

OK, so the picture I'm getting, both here and elsewhere, is that removing the tremulant/scanner gear is tricky and requires the right tools.

Removing the gear is necessary for disassembling the run motor if an internal repair were to be attempted.

Alternatively, you could use a later run motor by removing both gears and swapping the tremulant gear onto the later run motor.

If I don't have the tools necessary to remove a gear, might a clock repair shop be able to do it? After all, Hammond got his start in clocks . . .

[Drawbar Dave]

David, I found this in an earlier thread about run motors in general; https://photos.google.com/share/AF1Q...gwdHJkWmtVSmVB but I was looking for this thread https://organforum.com/forums/forum/...-motor-problem and this one with video tutorial https://organforum.com/forums/forum/...war-run-motors
I have a spare 50HZ 230 vac run motor for future use if my tremulant run motor dies so have taken an interest in this subject.

Hope this helps!

[ccw3432]

I used the method shown in the thread below on my Model A about 6 months ago or so. No problems so far. Thanks for the details Mark!

https://organforum.com/forums/forum/electronic-organs-midi/hammond-organs/36414-run-motor-gear-transplant-success

[David Anderson]

Luckily, I have a lead on a working replacement pre-war run motor, so fingers are crossed.....

[Drawbar Dave]

Luckily, I have a lead on a working replacement pre-war run motor, so fingers are crossed.....

How did it work out David?

[David Anderson]

I don't have the replacement motor yet.

[JoeyB3]

As Drawbar Dave mentioned in #8...I covered this briefly in my Concert E restoration video. It is a a fairly easy procedure to swap out gears between run motor housings. After the gear is replaced, you can lock it in solid (replacing the crimped lip) simply by putting in a thin line of solder. Easy Peasy.