# Shaft to Shaft motors any ME's out there?



## Duncan (Dec 8, 2008)

My tuppence worth
(retired Mech Eng)

There is no such thing as "impervious to slippage"- but a taper lock device like that is pretty damn good

Always worry about misalignment
But when you have it all assembled see what it feels like and put a clock on as many bits as you can reach
And if it feels OK and spins nice then try and misaligned it - try and move the drive shaft that sticks out - don't go mad but do put a tube on it and try and force it
I suggest about a two foot tube and as much force as you can exert with your hands

If you can't move it and it still spins nice dial the worry back to background worry

Should work OK - depends on the spline fitting - make sure that it is lubricated when you re-assemble - long term I would worry about fretting corrosion in the spline (that's why you lube it)


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## Tomdb (Jan 28, 2013)

One small issue design issue I would avoid. Make sure both motors can operate as a free unit. So make the adapter also a motor bearing.

Also the adapter should ride on the shaft, for concentric concerns. You would like to avoid alignment and clamping via one set of surfaces. 

Also the interface plates will be quite a pain to machine. So quite a big sum of money mainly due to the required accuracy. I would suggest making it one piece, as replacement for the faceplate for the "brown motor"

Mind sending me the CAD files, I will doodle up some of my ideas tonight.


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## winzeracer (Apr 3, 2012)

Duncan,

Thank you for the tips, I will definitely do those misalignment tests. And will make sure to clean up shaft corrosion and lube well, I hadn't though of the corrosion, very good point. I would love to do an interfernace fit, however then I couldn't really assemble the two.

Tom,

My thoughts on leaving the bearing out was so that there would be no bind between the two bearing on opposite motors, if there was a very slight mis alignment. But like I said I am not an ME, having the coupling ride on the adapter makes sense, concentricity is one of my major concerns. Two surfaces would definitely be better. As far as machining goes I have a friend that has a machine so I just have to feed him well and give him a nice holiday gift, which helps, none the less improving easy of machinability and saving machine time would be nice. Thank you for your words and help. I have attached the files, they are in SW 2015, I also included a .step file of the assembly. Thank you for reviewing the files I REALLY need and appreciate it!

Thanks,
Brock


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## RIPPERTON (Jan 26, 2010)

Being magnet rotors, removing a bearing from one motor could cause assembly problems and hence alignment problems.
I would extract the "brown" rotor and take it to the machine shop, get them to hob a spline or at least a keyway in the smooth end of the shaft.
You could box the magnet part of the rotor in wood to save your fingers.
Nice shots of the UQM's, not surprised they are so simple. Magnets sook skimpy though.


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## Tomdb (Jan 28, 2013)

Did some solidworksing.

Had a uqm apart afew years back, too much gunk inside for my taste holding in the stator. Rotor looks fine, however everything is a bit large 

The hub is heat shrunk onto the brown motor shaft, with the concentric expander already on the shaft. Once cooled and seated, the expanded is located and tightened down. 

The hub has an outer diameter for a ball bearing, sizing dependent on type chosen. Furthermore the hub has the uqm/brogwarner/siemens spline with shoulder to mate to the silver motor.

The flange will bolt to the brown motor, to complete it. The silver motor gets lowered on to the assembly bolts threaded onto the studs as lowered. Enough space is kept to allow the use of a ratcheting spanner. 

Just my quick mockup, I you got a 4 axis cnc or manual this might be quite do able. However it will require making alot of chips, not that that is a bad thing.


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## Duncan (Dec 8, 2008)

Hi guys

Brock's original design used 3 bearings - the silver motor had both bearings and the brown motor only had the outside bearing

IMHO that is actually better than trying to use four bearings - if you try and use both silver motor bearings and two bearings on the brown motor you will control both rotors better (I don't know how important that is on this type of motor) 
BUT you will be in trouble at the interface between the motors

Trying to hard couple two shafts each one with two bearings is normally a route to trouble


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## Tomdb (Jan 28, 2013)

Guys, please also keep in mind how the gearbox originaly gets coupled.

So "hard" coupling is no issue here, is you keep in mind the concentric machine faces with proper tolerance.


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## RIPPERTON (Jan 26, 2010)

Is a spline a "hard couple" though ?
I say 4 bearings and enough tolerance in the adaptor plate to let the spline dictate where concentric is.
If you have 3 bearings you are asking the spline to take the magnet pull from the single bearing motor.
That's going to make noise.
With 4 bearings you will be able to move one motor around until there is no noise.


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## Duncan (Dec 8, 2008)

Tomdb said:


> Guys, please also keep in mind how the gearbox originaly gets coupled.
> 
> So "hard" coupling is no issue here, is you keep in mind the concentric machine faces with proper tolerance.


Is the gearbox input shaft constrained by two bearings? 
Most of the ones I see have a single bearing and use the motor/engine as the second bearing


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## winzeracer (Apr 3, 2012)

Duncan said:


> Is the gearbox input shaft constrained by two bearings?
> Most of the ones I see have a single bearing and use the motor/engine as the second bearing












Looks like 2 bearings in the Egear?

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## Duncan (Dec 8, 2008)

That certainly looks like two bearings 
So the splines must have enough clearance to allow both shafts to be constrained

So if you can replicate that spline set-up a four bearing setup should be fine


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## winzeracer (Apr 3, 2012)

Tom, looks like some great Solidworxing, will look at it better when I get home tomorrow but at first glance it looks good. Thanks for rolling up your digital sleeves 

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## Tomdb (Jan 28, 2013)

guys stop worrying about the alignment it gets done alot by the twin dc motor guys. Example: https://youtu.be/ydAyODmuyvI

Bet the adapter will be some what pricey. Had to get one offs made for an uqm-brogwarner coupling cost around 300 euro's for a coupling, however when bought in tens only 50 euros a piece. Setup cost is a bitch.


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## Yabert (Feb 7, 2010)

winzeracer said:


> I have read that these mechanical interference coupling are "impervious to slippage" Does anyone have experience with them?


I've used Fenner drive keyless bushing in the past, never slip.
Should be the same for you if, but only if the installation is properly done (most important), if the surface finish is on the spec, if peak torque isn't exceed and if any other spec is respected.
IMHO, be safe and use at least a 2:1 ratio for the transmit torque capability.
The B-loc B112 (fenner drive) or the SLD 2600 (lovejoy) can transmit a lot of torque by their specific design.


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## RIPPERTON (Jan 26, 2010)

Winz
send me a stp file of the adaptor and I will see if I can make in on my CNC.


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## winzeracer (Apr 3, 2012)

Tom,

Looked at the design more, my first version was a single piece like this with bearing, however I wasn't thinking 4th axis and had no way to fasten hardware, I really like what you have here. Thanks again this is a huge help. Can you shoot me the files? I will go over them and make sure I get everything in the proper orientation and work on the details.

Danny,
Thanks for the offer, as soon as I have the files closer I will let you know. Do you have a 4th axis?

Thanks,
Brock

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## RIPPERTON (Jan 26, 2010)

winzeracer said:


> Do you have a 4th axis?


 Nope but wont need it. The recess's for the small PCD bolts can extend axially through. Don't need to go in radially.


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## winzeracer (Apr 3, 2012)

RIPPERTON said:


> Nope but wont need it. The recess's for the small PCD bolts can extend axially through. Don't need to go in radially.


Ya I see now. Awesome man thanks I will let you know when I finish the model.

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