Problems repairing PTO on my 682

[dlemaire]

I'm putting on a new armature on my 682 since my other one fried itself blowing a real wet snow.

I've run into a couple issues.

1. There is a spacer between the rotor and the bearing on the armature. If I stack the rotor, spacer and the armature together on the table, it looks from the manual that there should be a gap of .060-.090". Mine is more like .006". So do I need to find some shims for it?

I did notice the spacer is rounded on the ends as it is probably somewhat worn from rubbing on the bearing that was failing.

2. When I put the assembly on the crankshaft, the washer on the bolt going into the crank is smaller diameter than the crank itself? I'm thinking the washer should be touching the inner race on the armature bearing? Am I correct?

This is the way that I took it apart, which doesn't mean it was correct to begin with.

Any suggestions would be appreciated!

 

[jchamberlin]

David: Some pictures would help clarify things from this end. I've removed, reworked, and replaced the PTO on my 782 several times. I remember a 3/8" fine-threaded bolt (9/16" wrench size) and a relatively thick washer (at least 1/8" thick) that had fairly sharp edges, not rounded. I'll try to go out and snap a picture of it. The bolt/washer combination definitely kept the PTO from sliding off the crank shaft! Once the bolt and washer were removed, the PTO slid off easily most of the time.

 

[jchamberlin]

David

I'm showing two washers, I think the first is a split/ring lock washer, the second washer in the photo is the big, heavy one I mentioned earlier.

Please note, my pictures depict a Magnum 18 motor originally installed in an off-topic tractor marketed by a major US department store chain; but I suspect it is similar, if not identical, to the arrangement found on CCC/MTD (and IH) twin cylinder motors. I also had the same configuration on a 16 HP Briggs & Stratton twin cylinder that was installed in the 782 when I first acquired it. If the KT17 in your 682 is different, I would be surprised. At least you have one data point for comparison. Hopefully someone with an absolutely identical 682 setup will chime in with confirmation.

Edit: The Magnum has a spacer to bring the PTO out to the end of the crank shaft; I don't think the PTO would work well without the spacer. The crank needs the extension in order to align the belts with the mule drive and keep the belt tensioned correctly.

(The Briggs & Statton crank didn't take the spacer, and the alignment of the belts was more difficult, the mule drive couldn't really be tensioned correctly and there was very little clearance for the belts.)

 

[dlemaire]

John,

Thanks so much for the info and the pictures! That does help a lot.

I can see I definitely did not have the correct washer on the end and I think the spacer has been ground down and will need to be replaced, or I need to find some shims to push it out farther.

But I can't find a part number for the spacer/bushing. The parts diagram doesn't show it separate and I didn't get a new one with the new armature.

I'll try to take some photos of what I have and try to post them if I can figure it out.

 

[dlemaire]

I have the Warner armature, and I'm guessing I lost some material on my bushing when the bearing was failing and the wet snow heated it up.

But I could not find the part number for the bushing. So I suppose if I can't find a bushing I'll have to try to shim it to get the correct gap. Right now there is virtually no gap between the rotor and the armature disks and I don't think that is correct.

I'm attaching some photos of what I have and a picture of where the feeler gauge is that I believe is supposed to have a gap with the spacer installed. <center><table border=1><tr><td>

This is the armature and rotor with my old spacer.
Cub Cadet PTO clutch 1 (61.9 k)</td></tr></table></center>

 

[dlemaire]

 

[dlemaire]

This has the feeler gauge where I think there should be a gap when assembled with the spacer/bushing.}

 

[jchamberlin]

Dave: I've never done the repair you're attempting, but after reviewing the status of the PTO from the Briggs & Stratton that my son repaired, I may need to.

First, the PTO in the Briggs & Stratton requires dual inserts that (1) link the inside race of the bearing for back portion of the PTO to the crank journal, and (2) allow the inside race of the front portion to be "pinned" to the rear portion and thus also turn with the crank. See photo below.

Note also that while the inside of the rear portion is turning with the crank, the outside of the rear portion (the triangular part with the coil in it) is held stationary to the block with a cage or bar or some other apparatus.

See also the photos of the front and rear portions below:

A view of the side:

The air gap is a function of the front part of the cage: the part that is bolted to the front of the triangle. The height of the bolts determines how far away from the rear the front rides while at rest, or rather, when the coil is NOT energized.

I believe the User Manual recommend 0.010" to 0.015" and adds, "If brake plate drags on clutch, increase air gap to 0.020"."

When the parts are assembled as shown in your photograph, the brake plate would be resting on the rear, so there wouldn't be any clearance to measure. The unit needs to be assembled on the tractor, and the air gap adjusted until the brake plate is free to turn without dragging.

My unit ran fine for a year as shown, with an air gap --UNASSEMBLED-- of almost 0.070" and the brake plate installed backwards (at least that is how it appears to me now that I have it apart). I imagine the air gap would tighten up considerably once the bolt is tightened and front sleeve/insert is pinned to the rear.

So I learned something from trying to help you; I hope you learned something from my trying to help you.

By-the-way, I'm not so sure but what your "spacer" isn't an interior sleeve that must be pressed into the inner race of the bearing. The spacer installed in my Magnum 18 slides onto the crankshaft before the PTO is assembled onto the crank. Without the spacer in place there is at least 1/4" at the end of the crank before the bolt and washer. In other words, there is nothing for the bolt to do but sit there at the end of the crank, and the PTO is free to slip front to rear about 1/4" inch. I decided the spacer needed to be installed at the rear, and the tractor and the deck run fine, thank you.

 

[dlemaire]

Thanks for the explanation and photos. It looks like the model in the photos is a very similar design.

I still think that my spacer has lost some material in failure of the bearing and armature. And it would seem to me that the inner race of the armature should have a bushing inside of it to the crankshaft. Otherwise I have about 1/8" between the crank and inner race, which doesn't seem right.

Then I need to check the air gap with it assembled on the engine.

If I can't find a replacement bushing, I may need to visit a machine shop or find a used one. But there is no part number for it in the cub parts diagrams.

I'm out of town for a week, so it looks like it'll be on hold till I get back.

 

[jchamberlin]

Dave, perhaps the bushing/sleeve is still in the old armature. Just a thought

 

[dlemaire]

I did check that and unfortunately it isn't. The piece that I left is less than half the original length. So I guess that the smaller diameter that was inside the armature is gone.

When I took it apart as I mentioned earlier, the washer was only 3/4", and there was a large air gap as there was no bush between the crankshaft and the armature bearing inner race.

 

[jchamberlin]

Dave: OK, I get it (finally!). Your bush was eaten up by the self-destructive bearing.

I have to press (or beat) the bush out of my armature tomorrow so that I can reverse the plate. I suspect the bush is "stepped." The smaller diameter (I think) goes inside the inner race of the bearing the pulley rides on; the larger diameter keeps the armature (as you call it) "captive" to the front pulley assembly --so that it doesn't just flop around in there.

You seem to be missing a key part of the assembly!

No wonder you're posting on the forum.

Edit: I'll post pictures of my "bush" when I have it out tomorrow (no wise cracks, anyone).

 

[dlemaire]

You are correct. The 782 manual has a diagram of what the bush looks like. The 682 manual does not. But I think it's the same thing.

 

[jchamberlin]

David,

Now that I fully understand the problem, I can offer an idea of how to get to a solution. Again, since I removed my assembly from the 16 HP Briggs & Stratton motor that came with the 782 when I acquired it, I don't know that everything pictured below will transfer to your 682. On the other hand, I don't know but what the PTO installed on the Briggs & Stratton didn't come originally from the KT17 Series I that was originally installed in my Model 782. I can check with the previous owner, though, if need be.

Check the e-mail listed on your profile page, because I sent all the photos below to you in full resolution as taken with my 10 or 12 megapixel camera (Nikon Coolpix S550).

The whole part is 1.6225" by the digital readout of the caliper in my hand; 1.6186" by the micrometer tightened with the snubbing rachet wheel. (Disclaimer: both my instruments were made across the Pacific, but an experienced machinist calibrated the micrometer to the bars provided with the set.)

The OD of the larger "spacer" portion varies from 1.3535" to 1.3545" on the caliper in my hand; 1.3567" on the micrometer (I only took one measurement)

The OD of the "bush" section is consistently 1.1780" on the caliper in my hand; 1.1749" on the micrometer.

The length of the "spacer" or "shoulder section" is 1.204" to 1.206" on the caliper in my hand, depending on where I measure it, and how I hold the caliper; 1.2087" on the micrometer (I only measured one spot).

For the Inside Diameter (ID), I have to rely solely on the caliper, I don't have a reliable means of "miking" it. On the caliper in my hand I'm getting anywhere from 1.0135" to 1.0185" --it is obviously not concentric (or I'm having real problems getting a measurement). I remember the entire PTO assembly easily slipping on and off the crankshaft.

For the wall thickness measurements I must also rely on the calipers. I'm getting a consistent 0.166" for the wall thickness of the "spacer" or "shoulder" section on the caliper in-hand; I'm getting a reading of between 0.080" to 0.078" for the wall of the "bush," although the 0.078" reading predominates.

Again, I'm not a machinist, and the instruments don't carry a certificate of recent calibration. But if you need me to take another measurement or verify one I have posted above, e-mail me or use the contact info in my e-mail to you.

Good luck, hope this helps.

Edit: The part was not pressed into the pulley bearing it fell out as soon as I pushed on it with a 13/16" socket, I never had to strike it.

 

[jchamberlin]

David,

After reviewing pictures of your assembly and comparing it to mine, I would say there are differences. The bush/spacer for my unit is "captured" at both ends. The small "bush" end fits inside the inner race of the pulley or "armature" portion; while the larger "spacer" portion fits inside a 0.104" deep "lip" on the magnetic rear portion of the PTO, see below. The depth of the inset can be seen as the shiny portion at the end of the "spacer/shoulder" section in the pictures I posted earlier.

Thus, the two pieces are effectively kept apart by a space of about 1.100" as measured on the caliper.

I can't see that your rear portion "captures" the thicker "spacer" portion of the bushing. At the other end, if you are finding a lot of play between the inner race of the pulley/armature and the crankshaft, and if the "bush" portion of your spacer was chewed up and spit out by a frozen bearing, then I hope your crankshaft did not also suffer damage.

Regarding the unit's function, it seems to me that there definitely needs to be a space maintained between the rear and front portions of the PTO, but I'm not clear why the pulley/armature portion needs to be bushed. The only reason I can think of is to prevent damage to the crank by eliminating any chance that the pulley would "ride the crank" when the PTO wasn't energized.

I can also testify that the friction portion of the front pulley/armature section cannot be "flipped around" --it is integral to the pulley by virtue of the rivets holding it to the pulley itself. (I don't know why I thought it could be removed.)

Anyway, I've now got to go out and figure out how to repair the damage I did to the sheet metal of the pulley while getting the bearing out. It a wonder how these things are made! It must be an awesome machine that forms the pulley and the contoured hole that grips the bearing's outer race.

All things considered, all your problems seem to be spacer/bush problems.

--Honestly!

 

[digger]

Here's the bushing David needs that's headed his way as I type.

 

[jchamberlin]

Wow! Charlie, you're a life-saver. I'm sure David will appreciate it. Good picture too.