# Twin motors? Just a thought...



## CroDriver (Jan 8, 2009)

I think that this setup would make sense only if you don't have enough space to line them up since you will have some looses in the chain drive


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## kek_63 (Apr 20, 2008)

I remember seeing a Fiero on evalbum.com that had two motors stacked with a belt drive to the gearbox.


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## jackbauer (Jan 12, 2008)

I have seen it done in other threads here and elsewhere. I think there is one called bmw bimoto or somesuch. Problem with pump motors is that they are usually shunt wound.


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## Woodsmith (Jun 5, 2008)

I think motor length would be a problem for transverse and mid engine layouts. It may put to use some of the smaller series wound fork truck motors that find their way into bikes and trikes.
Three or four (or five) tiddlers around a central gear would make for an intersting drive train.


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## Tesseract (Sep 27, 2008)

Woodsmith said:


> I've seen Siamesed motors running on a common axis making one long cylinder. Has anyone tried two smaller motors side by side to gear or chain drive a gearbox shaft?
> 
> Just thinking of all these 'too small' pump motors that are discarded.


I believe the EVPorsche guy (Paul Liddle?) has done this sort of setup with a toothed belt drive connecting the two motors to a single output shaft.

As others have noted, there is a slight loss of efficiency going this route compared to coupling the shafts together directly, but thems the breaks, as they say.

Another bad thing is that belts and chains are much more likely to break in this type of application so you REALLY need overspeed protection, and if you use two separate belts/chains to couple each motor then you need DUAL overspeed protection.

I confess I did not anticipate such a need when I was designing the hardware for the Soliton 1... Otmar apparently did for the Zillas, though.


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## Woodsmith (Jun 5, 2008)

I see it isn't as simple as when folks put twin motors on their warn winches then.








Twin 12v 6hp motors running at 24v and water cooled.


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## Drew (Jul 26, 2009)

Offsetting the motors will mean another step in the drive drain which will result in additional maintenance requirement and losses, linking motors end to end doesn't result in similar losses.


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## Jozzer (Mar 29, 2009)

Sometimes theres just no other way..

Motors not fixed in correct positions in these shots (they will be level), and chain not yet connected. Vehicle is a 400KG trike with a renault 5 gearbox. She'll be test driven within 2 weeks I hope


Steve


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## Woodsmith (Jun 5, 2008)

That's great! Looks a little like an old Morgan three wheeler.

What are you doing for a chain tensioner?


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## Jozzer (Mar 29, 2009)

It looks like one, but is actuallly a "Hudson Kindred Spirit". (much cheaper renault based kit car). 

The motors are both adjustable, I plan to attempt just to set the chain tension to the right level and hope it behaves itself. I generally convert motorcycles, so I'm in new territory here!
Thought about a single series motor, but was scared off by awfull efficiency ratings and lack of sensible regen options, not to mention weight! I'll get around 40HP continuus from the pair, and they weigh just 11KG each!

Steve



www.jozzbikes.co.uk


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## Woodsmith (Jun 5, 2008)

You could put an eccentric adjuster on the motor frame where it locates on the mount. Rotating the whole motor would adjust the tension.
Or you could set the mounting so that the motors both pivot on the lowest bolt mounting and the top of the motors are pushed apart on a threaded adjuster before the other bolts are locked down tight.

Both ways would give you a secure location at the required tension. That way any slack would be from chain wear and not the motor slipping on its mounting.


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## Jozzer (Mar 29, 2009)

Thought of that idea, but decided to try KISS first. If things move I'll address it later..


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## Drew (Jul 26, 2009)

These are the Axial PM motors aren't they? I remember looking at the manufacturers website and they had a two motor configuration which was extremely compact.

The big problem you're going to find with a chain type installation in that close a quarters is that the shorter a chain is the harder it is to establish the correct tension and the faster it loses it.

You might be able to get around this by using a spring loaded idler to tension the slack side of the chain, but I'd still recommend going for an inline setup or alternately looking at gear drive.


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## Woodsmith (Jun 5, 2008)

A sprung tensioner would be a fairly easy to attach at a later time looking at the lay out and the size of the mounting plate.


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## Jozzer (Mar 29, 2009)

Yes indeed, very easy to retro fit.

I already used a sprung tensioned approach on the TTX01 GSXR bike we produced for the TTXGP demo vehicle last year, and decided to try without it since it added to the chain noise quite considerably.


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## Bowser330 (Jun 15, 2008)

Jozz, these look like agni motors...very cool...I hope you opted for the 72V 400A (26kw!!) 95-series

is i possible to stack these motors and connect their output shafts that way?


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## Jozzer (Mar 29, 2009)

Stack them front to back you mean? Afraid not, though I know there is an LMC motor available that can be stacked (or at least bought in pairs).


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## JRP3 (Mar 7, 2008)

One of my favorites:










I prefer belt drive to chain, much quieter, no stretching, no lube flying around. 
http://www.youtube.com/watch?v=hRhOrW7kva8


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## Woodsmith (Jun 5, 2008)

JRP3 said:


> One of my favorites:
> 
> 
> 
> ...


Now that's what I'm talking about!


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## Salty EV (Jun 8, 2009)

Since it was mentioned possibly using several smaller motors, what if you attached them on the adapter plate to transmission, but drive the flywheel via the starter motor gears. The best way to visualize this is, imagine how the stock starter motor is, but now make that one bigger, and now add several around the flywheel, almost like a ring of motors (think revolver, but motors instead of bullets). It would also be nice because adapting it would just be a matter of attaching the starter gear to the shaft of the new motors.

Downsides I imagine would be you would need high rpm motors because the gear reduction is fairly high, no lubrication for the gears since this will be constant duty now, and I do not know how much torque the flywheel can take driven by those gears. Would look pretty cool thought i think.


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## JRP3 (Mar 7, 2008)

That's kind of a planetary gear setup, but it wouldn't last long without lube.


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## Dennis (Feb 25, 2008)

I suppose one could argue that a V8, V6 or I4 ICE's are nothing more than single cylinder engines put into one compact package. I suppose this line of logic could be used to make some kind of multi motor setup made up of a bunch of small motors driving a central output shaft much like the pistons have their connecting rods connected to the crankshaft of an ICE. I don't see this being practical, but someone on here will try this setup. We already have duals so now it is just a matter of time till someone out there builds a quad setup.


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## Drew (Jul 26, 2009)

Dennis, from what I understand the length of a motor or the number of plates in an axial flux motor is analogous to the number of cylinders in an ICE.

That being said, there are a few motors I've seen which seem to be designed to stack end to end. I would be interested to see what torque rating the output shaft has in these systems.


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## Abel (Sep 16, 2009)

Hay If you wont to run a twin motor set up. You are going to need to a spring/hydraulic tensioner and some slack in your set up. The reason why is that as we all know you have MAX torcque at 0 RPM so the tensioner will exurb the exes torque and you wont brake something down the line.


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## goglahey (Jul 8, 2009)

Jozzer said:


> Stack them front to back you mean? Afraid not, though I know there is an LMC motor available that can be stacked (or at least bought in pairs).


On the Agni Motor bike at TTXGP it looks like two Agni 95 face to face?

/Allan


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## Woodsmith (Jun 5, 2008)

goglahey said:


> On the Agni Motor bike at TTXGP it looks like two Agni 95 face to face?
> 
> /Allan


Twin Agni 95s fitted to a Ford Fiesta in the UK








The Agni's are set to run in opposite directions and then shafted face to face onto a common toothed belt pulley. The belt then drives a pulley on the gearbox primary shaft with a bearing on the adaptor plate outboard of the pulley to support the drive loads. The motors are on a frame that pivots to adjust belt tension.


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## goglahey (Jul 8, 2009)

Nice, thats the project i'm aiming at only on a quad.


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## Jozzer (Mar 29, 2009)

The Agnibike does indeed use twin Agni motors face to face.

My Hudson Trike hit the road this weekend with its chain coupled Agni's and runs very well. Will have to do something with the chain noise, its all pretty open at the moment, byt an ally chain guard and a cover for the hole in the bonnet where the carb used to breath will improve things.
Sounds like Darth Vadors attack ship at present, which really turns heads

I seem to be getting about 120WH/mile razzing it about town efficiency wise, I doubt I'd get close to that with a big series motor..

Steve


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## JRP3 (Mar 7, 2008)

Have you considered going to a Gates toothed belt drive? Quieter, no lube to worry about, no stretching. I've been very happy I switched my AMPhibian over to belt drive.


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## Jozzer (Mar 29, 2009)

Yes indeed, a belt would be far better for this drivetrain. Unfortionatly I'm very busy with another project and for now this will have to do. I'm looking forward to finishing it one day. Perhaps when I'm ready you can help advise the easiest approach..
Still to do are packing the batteries to maximise range (100 miles+ should be feasable, I have enough cells sitting here waiting), adding a roof to help streamlining and weatherproofing, fitting of a belt drive, and perhaps finding a better choice of gearbox.


In the meantime I will have to "put up with it" as it is, whilst I concentrate on making more electric racebikes! It already however is quieter, cleaner, faster annd more economic than the the 1300cc engine originally fitted..all iin all I'm quite happy with my first car conversion

Steve


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## Bowser330 (Jun 15, 2008)

Is it possible to make larger agni motors? is the efficient technology involved limited to smaller sizes and smaller power outputs?


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## Woodsmith (Jun 5, 2008)

Bowser330 said:


> Is it possible to make larger agni motors? is the efficient technology involved limited to smaller sizes and smaller power outputs?


I've been hoping that Agni will make stacked or stackable motors.

Maybe with splined male shaft at one end and splined female at the other end. That woiuld make an easy stack.


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## EV-propulsion.com (Jun 1, 2009)

A few months ago I saw someone on Ebay selling a pickup truck that used 9 (yes, nine) treadmill motors mounted to a plate to a common gear that drove the input shaft of a transmission. It was all chain driven. Probably not too efficient, but he had some decent speed results. And he probably got the motors for free too! I'll have to see if I can find it.....
Mike
www.EV-propulsion.com


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## JRP3 (Mar 7, 2008)

I think I saw that as well, and it looked like a disaster waiting to happen.


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## boyaka (Oct 10, 2009)

if you can line up you motor you can do what plasma boy did and make a monshaft or make a conecter he had conecter before here is the site
http://photos.plasmaboyracing.com/buildsequence


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## Crash (Oct 20, 2009)

EV-propulsion.com said:


> A few months ago I saw someone on Ebay selling a pickup truck that used 9 (yes, nine) treadmill motors mounted to a plate to a common gear that drove the input shaft of a transmission. It was all chain driven. Probably not too efficient, but he had some decent speed results. And he probably got the motors for free too! I'll have to see if I can find it.....
> Mike
> www.EV-propulsion.com


This is probably what you're talking about:
http://www.youtube.com/watch?v=z8T5ho__HcQ
http://www.youtube.com/watch?v=jt7cQvLhy3c


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