Coupler Suggestions??

green caveman said:

Woody,

I think that the flywheel and clutch are here to stay.

Good thought on supporting the weight.

I'm not sure I buy into the spline theory though, after all, the connection to the tranny is a spline. The flywheel is heavier, but the spline is a pretty tight fit and the extra space can be filled, even if with something like silicone. Unlike the transmission it doesn't need enough play to move.

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If you can slide it on it is slack and free floating. In engineering terms a pretty tight fit would require pressing on. A tight fit would require the outer to be heated and shunk on.

There is a reason why the original flywheel was mounted with 6-8 bolts onto a flange that locates inside a lip on the back of the flywheel and possibly in the hole in the centre.

There is a lot of mass, even when lightened, to have on anything but a rigid connection. If you go over a bump the mass of a static flywheel will move on the spline. If it is also spinning then you will have dynamic and centripital forces all acting whenever the vehicle moves, bumps, jolts, etc.
The spline fitting would only really be useful if it was a very tight shrink fit onto the shaft. In reality there is too much spinning mass for this to be useful as there would be no way of ensuring it is spinning true given the diameter of the flywheel. Fine with a gear wheel but the large diameter exaggerates any discrepancy.
Even with a taper lock there is a need to check with a dial gauge, while the bolts are being tightened, that it is staying true and aligned.

The primary shaft of your transmission also need to locate in the bush that would have been in the end of the crank shaft. That will need to be replicated on the coupler in the centre of the flywheel. Again, even the slightest movement and the clutch could clamp the driven plate off centre leading to greatly increased vibration.

Look at the arrangement from the motor though to the transmission.

Rigidly located motor shaft on two bearings.
Coupler and flywheel free floating.
Clutch plate free floating.
Transmission shaft supported on one bearing on inner end and free floating at the clutch end.

There is a lot of free floating spinning mass that will suffer misalignment whenever the clutch pedal is depressed and released.

Thanks green, I am just contributing what I learn to help others, like the crew on this board has helped me. Give credit to the whole, not the one, because the forum makes all this possible.

Unfortunately, I have to agree with the consensus here. Having that same motor and PTO combination, I know for sure it is a slip-fit connection that is only good for transmitting torque. I suspect that whatever these motors plugged into on the Hyster forklifts had a shaft or hub that was also supported by bearings because the shaft also seems to be cut and treated for a slip-fit connection. I say that because the PTO hub fits and rides on it like it was meant to be there - just like a clutch disc would on a transmission input shaft, or a driveshaft yoke on the output shaft. Those shafts often have some type of hard-chrome like surface, and my motor shaft appears to have this as well. If you mount a flywheel to that, you're going to have one heckuva wobble! If you're able to drive it, I would guess that it would eventually break the motor shaft. Sorry.

What you really need is to find a sealed roller bearing with a large enough internal diameter to fit over an adapter made to mate the PTO hub to the flywheel. A quick search on McMaster turned up plenty of bearings with a large enough center hole, but not rated for the motor speeds you'll turn. I didn't do an exhaustive search though. The bearing would fit over the adapter, and into a race or register in the adapter plate. That means the adapter plate would be carrying all the radial loading of the flywheel.

The problem is a bearing that size is going to be expensive. A thin bronze sleeve bearing would be ideal for size and cost, but lubrication becomes an issue.

The other caveat is your machinist has to be spot on with the coordinates and machining. Any misalignment is going to put a bind on the motor and/or transmission shafts. Eventually something is going to give if there's a bind. Best case is just a trashed bearing.

green caveman said:

...I'm thinking that there is (maybe) enough spare material on the PTO disk to machine it parallel over, say a 3/4". Attach the PTO hub to the flywheel and then use a flange bearing over the PTO hub attached to the adapter plate. (Some possible spacing problems here).

Still doesn't seem like much support to me, but I'm (obviously) not a good judge.

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That might be a workable idea. I would want more than 3/4" though. Ideally, you want to push the bearing as close to the flywheel as possible, to avoid having the weight of the flywheel hanging on the end of the machined hub, and placing side loading on the bearing. You should be able to find a bearing that would require minimal machining of the hub. He'll also need to turn a (slight press-fit) spindle for machining the PTO. It can be made of a slightly softer material to avoid damaging the splines. Again, the machine work needs to be very precise.

You also need to think about keep the flywheel in place, longitudinally, on the shaft. Since the motor shaft is drilled and tapped, you may be able to use a small bolt with a thrust bearing inside the PTO-to-flywheel adapter. So you would press the bearing into the adapter plate, install it on the motor, bolt the PTO and fywheel together with the adapter, install the trust washer, slip it on the shaft seating the machined PTO hub in the bearing, lock it together with a small bolt, install clutch and transmission...

There is also the possibility of shaving that center ring off the motor's DE head to get the whole assembly seated closer to the motor. That would require less thickness in the adapter plate, or fewer components to build it.

Doable, but there are a lot of components to get right. Not saying anything bad about your machinist but, as some of us have learned, it's easy for them to underestimate an automotive powertrain system and not get it quite right. You have to be like a fruit fly buzzing around their head incessantly screaming about precision. If they get annoyed with that mandate, or seem opposed to considering it from every possible angle, or are in a rush to get it done, you might consider testing them on something less critical first.

toddshotrods said:

I would want more than 3/4" though. Ideally, you want to push the bearing as close to the flywheel as possible, to avoid having the weight of the flywheel hanging on the end of the machined hub, and placing side loading on the bearing.

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3/4 is all you get on that PTO hub. I was imagining the PTO hub attached directly to the flywheel, so the bearing would be pretty close.

It may not work because we still need 1.7" or (1.706?) from the front of the transmission to the flywheel clutch plate (magic number).

It might be easier just to machine a short shaft that bolts to the flywheel and uses the existing bolt holes in the PTO hub. With the bearing on that shaft we can make it any reasonable length.

Maybe something like the attached sketch?

toddshotrods said:

You also need to think about keep the flywheel in place, longitudinally, on the shaft. Since the motor shaft is drilled and tapped, you may be able to use a small bolt with a thrust bearing inside the PTO-to-flywheel adapter. So you would press the bearing into the adapter plate, install it on the motor, bolt the PTO and fywheel together with the adapter, install the trust washer, slip it on the shaft seating the machined PTO hub in the bearing, lock it together with a small bolt, install clutch and transmission...

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More argument in favor of a shaft. It'd be hard to do this with just the PTO hub.

toddshotrods said:

There is also the possibility of shaving that center ring off the motor's DE head to get the whole assembly seated closer to the motor. That would require less thickness in the adapter plate, or fewer components to build it.

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Interesting thought. I'm still not absolutely certain that the motor is going to clear the front diff.

toddshotrods said:

Doable, but there are a lot of components to get right. Not saying anything bad about your machinist but, as some of us have learned, it's easy for them to underestimate an automotive powertrain system and not get it quite right. You have to be like a fruit fly buzzing around their head incessantly screaming about precision. If they get annoyed with that mandate, or seem opposed to considering it from every possible angle, or are in a rush to get it done, you might consider testing them on something less critical first.

Click to expand...

Judging is a little out of my league, but he seems pretty detailed. The trick seems to be getting the SolidWorks models right (which you can tell is out of my league just by looking at the sketch!).

toddshotrods said:

Doable, but there are a lot of components to get right. Not saying anything bad about your machinist but, as some of us have learned, it's easy for them to underestimate an automotive powertrain system and not get it quite right. You have to be like a fruit fly buzzing around their head incessantly screaming about precision. If they get annoyed with that mandate, or seem opposed to considering it from every possible angle, or are in a rush to get it done, you might consider testing them on something less critical first.

Click to expand...

I machinist offered a favour in machining the coupler for my 12" motor. The favour has left the motor unusable as the shaft is no longer concentric to the armature and the coupler and bearing support are not concentric nor square to the axis of the armature. As the armature is without a bearing and relys on the coupler to provide a bearing surface the motor is now U/S unless I spend around £400+ on reshafting it.

Try to design around using a proper bearing rather then say one of these.

They allow for misalignment and so it would be much more difficult to ensure that it is properly aligned

You can make up a similar shaped bearing cap to support a single or double row bearing that rides on the outside of the PTO centre. It can be bolted to the front of the DE cap and then the flywheel bolted to the modified PTO centre.

Here was my 12".
This is the DE. The shaft in not supported and the bearing is larger then original in the DE cap.


This is the end of the crank shaft machined and bored out to fit the shaft.


This is the crank end being pressed onto the shaft and though the bearing.


This is how it looks when pressed most of the way home.


When all the way home it should look like this with the flywheel and clutch on the trans. In this shot the rest of the motor and armature were removed to figure out why it wasn't concentric.

Here are some alternative shots of the DE cap with the bearing carrier in place.

There is a flange around the shaft on the outside of the DE cap.


Can that be used as part of the bearing support for the bigger bearing?
It could maybe take half the thickness of the big bearing and then a cap can be made that supports the outer half of the bearing and locates on the outside of that flange.

It will mean machining the DE but I figured you have to machine it anyway.

Here are some photos of my 11" motor.

The shaft at the DE has no bearing surface.


The bearing is on a spur gear that I removed from the forklift axle.



When the spur gear is fully on the shaft it protrudes this much from the frame. One bearing will be fitted in the new DE cap to take the inner end of the bearing.


Mine will be used for a chain drive and so once the DE is made I can then make a second component to support a bearing on the outer end of the spur gear. The spur gear will be machined down to take a chain sprocket.


So although different application I have the same problem of a floating splined 'tube' that need to be controlled.
I will most likely use two bearings, one on each side of the sprocket but I will try shrinking the spline tube, when the gear teeth are machined off, and then using a bolt to pull the tube tight onto the motor shaft. I can consider risking this as there is much less risk with dynamic misalignment (as there is no flywheel weight), only increased chain and spline wear. It will do to test and set up initially.

toddshotrods said:

That could work, but I thought you were already tight on space for the motor. That adds a matter of inches!

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I just remeasured the thickness of the flywheel - ~1.5", so there is more of a space constraint than I remembered.

This means that Woody's idea of just using the flange on the DE of the motor as a bearing holder and machining down the PTO may work and be fairly simple (1.7 is the target distance). That leaves the problem of attaching the PTO hub to the flywheel. If it's going to be a direct connect, it would be hard to bolt, but I didn't get much of an uptake on the idea of welding it, but I suspect that even if that's possible balancing it afterwards would be a challenge.

With another shaft, since that would increase the distance, it would just take some really creative machining of the adapter plate to get all the pieces spaced correctly. Something like a bearing mounted into the back of the plate and the motor mounted on the front. I have a 2" block of aluminum for the adapter plate so it may not be impossible, but I suspect that even with that it would take some spacers on the motor side to get enough length.

We'll either clear the front diff or we won't, the extra shaft doesn't matter. If it clears it, there's space under the hood for the motor. Of course, we can't be certain that it's going to clear it until everything is back together. We still have to figure out the location of the transmission, the only suggestion I've seen for that is to make sure that the driveshaft is straight.

Woodsmith said:

Caveman, can you post a side view of the pto centre?
Maybe put a ruler next to it for scale.

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Here's the image.

Thanks.

I am assuming that the other side of the disc has a small centre hole and some more of the splined part pokes through?

Both ends could be machined parallel and a thick flange made up to bolt between the PTO flange and the flywheel recess. Bolts could then be used to couple everything together.

Except that the bolt heads or nuts would protrude out where you have the ruler now.

So make a steel flange to fit the flywheel and then weld it to the PTO centre both around the rim of the flange and through the holes to plug weld. The steel flange can be made a shrink fit onto the PTO centre so that it is tight and square before welding.
After welding it can be machined true by pressing a shaft through the centre and turning. Alternatively the shaft can be a three part unit. Two cones on a smaller shaft. The shaft can be threaded like a bolt and a nut used to tightern the cones together to locate and centralise the PTO spline. A DTI gauge will confirm it is true.
After turning true the other end of the PTO, where your ruler is, can then have a bearing put on it.

Once the PTO centre is true it can be slipped onto the motor shaft and pressed into the new bearing that you have fitted with a new bearing retainer cap.
A cap screw and shaped plug can be wound into the threaded hole in the end of the shaft to keep the PTO centre pulled in tight.
The welded on part that fits the flywheel will also have a hole in the end that suits a bush for the transmission primary shaft.
The flywheel can then be bolted on to threaded holes with thread lock.