how to rewind a pto clutch

826 Views 49 Replies 4 Participants Last post by chuckv, 3 d ago

CharlesA.

Discussion Starter · 12 d ago

Hi, I figured out how to fix my PTO clutch on my 72' JD 112 sf without getting a new one, but I need to rewind the clutch, does anyone know how to do it, wire to use, etc?

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chuckv

· #2 · 12 d ago

Charles,

This thread below from the FAQ discusses rewinding the PTO coil for the 318 -- the process should be similar for any electric clutch. The wire used is "magnet wire" which has a very thin flexible insulating varnish allowing the most turns of wire in a confined space. The strength of an electromagnet is often stated in "ampere-turns" which describes the magnetic field strength as being dependent on the number of turns and the current flowing though the wire... Most PTO windings have a resistance of around 3.4 to 4.9 ohms, and you can consult wire tables to see how many feet of various gauge wire results in such a resistance range. Most PTO windings use 22 gauge...so you would need about 250 feet or so.

Rewinding clutch coil

Does anyone happened to have saved this thread about rewinding a clutch coil? I can get the pics but would really like to read the thread! Looks like I'm gonna have to either buy a new coil (ouch!) or rewind mine. Would really like to try the rewind. Thanks!! (Message edited by robb318 on...

www.wfmachines.com

Could you post a picture of the area where your wire will lay in your PTO ? I would expect it is similar to the 318 style clutches but not sure... Do you have any information on what the resistance of a "good" PTO for your tractor would be?

Chuck

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CharlesA.

Discussion Starter · #3 · 12 d ago

chuckv said:
Charles,

This thread below from the FAQ discusses rewinding the PTO coil for the 318 -- the process should be similar for any electric clutch. The wire used is "magnet wire" which has a very thin flexible insulating varnish allowing the most turns of wire in a confined space. The strength of an electromagnet is often stated in "ampere-turns" which describes the magnetic field strength as being dependent on the number of turns and the current flowing though the wire... Most PTO windings have a resistance of around 3.4 to 4.9 ohms, and you can consult wire tables to see how many feet of various gauge wire results in such a resistance range. Most PTO windings use 22 gauge...so you would need about 250 feet or so.

Rewinding clutch coil

Does anyone happened to have saved this thread about rewinding a clutch coil? I can get the pics but would really like to read the thread! Looks like I'm gonna have to either buy a new coil (ouch!) or rewind mine. Would really like to try the rewind. Thanks!! (Message edited by robb318 on...

www.wfmachines.com

Could you post a picture of the area where your wire will lay in your PTO ? I would expect it is similar to the 318 style clutches but not sure... Do you have any information on what the resistance of a "good" PTO for your tractor would be?

Chuck

Are you sure its 250 ft?

CharlesA.

Discussion Starter · #4 · 12 d ago

Would this work? https://www.amazon.com/Science-Proj...85127971&sprefix=22awg+magnet+,aps,123&sr=8-5

chuckv

· #5 · 12 d ago

Charles,

22 gauge copper wire is 16.2 ohms per 1000 feet, so 250 feet would be 4.05 ohms -- pretty near the center of the 3.4 to 4.9 ohm range... If you can make a bit more wire fit in the space allowed on your spool, it would not hurt anything.

Yes, the wire you show in the on-line ad above will work. Were you able to get a "nominal" resistance value for a PTO coil of your style/type? Were you able to probe the broken wires to get a reading??

Chuck

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CharlesA.

Discussion Starter · #6 · 11 d ago

I'll try probing them.

CharlesA.

Discussion Starter · #7 · 11 d ago

Is it normal to not have continuity?

chuckv

· #8 · 11 d ago

No, an open coil is a failure for sure... Since the wires have been sheered off, they also may be broken further inside, so when you take apart the assembly to rewind it, look carefully at what may be additional failure issues.

It appears that the leads at the surface in your picture may be stranded wire, so there is a transition to solid magnet wire somewhere inside. When you take this clutch apart, take lots of pictures so it can be re-assembled correctly (and we may learn more about how it failed...)

Chuck

Reactions: 1

CharlesA.

Discussion Starter · #9 · 11 d ago

They were cut by the PO.

CharlesA.

Discussion Starter · #10 · 11 d ago

Wire is on its way.

chuckv said:
Charles,

This thread below from the FAQ discusses rewinding the PTO coil for the 318 -- the process should be similar for any electric clutch. The wire used is "magnet wire" which has a very thin flexible insulating varnish allowing the most turns of wire in a confined space. The strength of an electromagnet is often stated in "ampere-turns" which describes the magnetic field strength as being dependent on the number of turns and the current flowing though the wire... Most PTO windings have a resistance of around 3.4 to 4.9 ohms, and you can consult wire tables to see how many feet of various gauge wire results in such a resistance range. Most PTO windings use 22 gauge...so you would need about 250 feet or so.

Rewinding clutch coil

Does anyone happened to have saved this thread about rewinding a clutch coil? I can get the pics but would really like to read the thread! Looks like I'm gonna have to either buy a new coil (ouch!) or rewind mine. Would really like to try the rewind. Thanks!! (Message edited by robb318 on...

www.wfmachines.com

Could you post a picture of the area where your wire will lay in your PTO ? I would expect it is similar to the 318 style clutches but not sure... Do you have any information on what the resistance of a "good" PTO for your tractor would be?

Chuck

See less See more

chuckv

· #11 · 11 d ago

Charles,

That is much better access than the coil on the 318-style PTO clutches...and you can count the number of turns per layer and the number of layers to ensure you get a similar number of turns on your replacement coil.

I don't see where the exit wires are attached to this coil -- are they on the bottom surface? Have you found the place where the open circuit is?? Does that coil bobbin come further off the metal core? If so, there is still a chance it could be repaired rather than replaced/rewound.

Chuck

CharlesA.

Discussion Starter · #12 · 10 d ago

The wires are attached inside the metal, you have to take the wire out to get access.

CharlesA.

Discussion Starter · #13 · 9 d ago

Got the wire I, I'll try it tommorow.

bob_r

· #14 · 8 d ago

These are pictures of an original 73 112 PTO coil. What often happens (ask me how I know) the outer bearing as can be seen in photos, seizes and breaks the arm that holds the coil stationary. When that happens, it spins the coil and tears the wires out. If you are successful rewinding the coil, I highly recommend you also replace the outer bearing. Also check the OD of the shaft the coil slides onto to be certain the bearing didn’t spin on it enough to wear it down.

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CharlesA.

Discussion Starter · #15 · 8 d ago

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CharlesA.

Discussion Starter · #16 · 8 d ago

I have continuity, I guess it should work?

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CharlesA.

Discussion Starter · #17 · 8 d ago

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CharlesA.

Discussion Starter · #18 · 8 d ago

What should I seal/stick it together?

chuckv

· #19 · 7 d ago

How many turns did you get on there and what is the resistance?? Potting compound (usually an epoxy) is what is used to give mechanical stabilization and strength to a winding such as this...

Are you sure you got enough turns -- looks like a single layer or two. How many feet of wire were used???

Chuck

Reactions: 1

CharlesA.

Discussion Starter · #20 · 7 d ago

I decided to redo it because it seemed kind of wonky. I got one layer done for the new winding.

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