# Motor for small tractor



## palmtree (Jul 14, 2016)

I'm in the process of converting a small tractor to electric drive. The original engine is 12hp but the same tractor had options up to 18hp. I'm doing this on a tight budget so looking for a used forklift motor. I am having difficulty finding an appropriate motor mostly due to the lack of available specifications on these old motors. I'd like to find one in the 6-7 inch range that I can get up to 3600 rpm. I assume the duty rating needs to be continuous or at least rated for 1 hour. Does anyone have any suggestions? I've read the the massive forklift motor thread and it is helpful but overwhelming.
Thanks


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## remy_martian (Feb 4, 2019)

Forklift is massive overkill for your application. Something likecan etek, at around 15kW is lighter and won't tear up your belts.


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## palmtree (Jul 14, 2016)

Those ETEK motors seem great but they are expensive and also pretty light weight. My tractor is a gravely 812. It has a rear gas engine that is mounted directly to the transmission (no belts). I think it's important to have the weight over the rear wheels. Especially with all the batteries under the hood in front.


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## cricketo (Oct 4, 2018)

6-7 inch forklift motor ? Is that a typo ?


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## palmtree (Jul 14, 2016)

cricketo said:


> 6-7 inch forklift motor ? Is that a typo ?


It wasn't meant to be. Maybe that's too small for a forklift? I have been wondering about a ride on pallet jack drive motor. They are mostly 24v -- I wonder if they could handle 48v.


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## cricketo (Oct 4, 2018)

ok. You can ask this guy what the size of the motor is CR-114330 Motor 24 Volt Crown Forklift Used Parts | eBay


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## remy_martian (Feb 4, 2019)

What exactly does this tractor do? I don't see a PTO or hydraulics. Every belly mower deck I've seen uses V-belts.

Cricketo's motor will not work. Don't understand the 48V battery, though - you said 3600RPM.

edit: that's a pump motor rated at 20% duty cycle. No good for a traction motor.


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## palmtree (Jul 14, 2016)

It can run a belly mower. There's a pto shaft coming out the front of the trans. I won't be mowing with it. I'll just be using a front blade and pulling a harrow and a roller. The roller weighs 800lb so it'll need to have some guts. Ya I need a motor that's rated for at least 1 hour of continuous use. 
Thanks for all the input so far.


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## palmtree (Jul 14, 2016)

Is it unrealistic to hope to get 3600 rpm with 48v?


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## remy_martian (Feb 4, 2019)

Motorize the roller 😂

You crank the voltage up to get more speed (horsepower) and push more current.


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## palmtree (Jul 14, 2016)

Now that I think about it more -- I don't really need 3600 rpm since I won't be using it for mowing. I just don't want to build a "crawler". It does have 8 speeds, so surely 8th gear would be a reasonable speed at a lower rpm. The manual recommends to run it at 3600 rpm, but that's for mowing with a 50 year old 12hp gas engine with a torque curve far different than a stout electric motor.
I'm not opposed to having it chain driven, which would allow my to manipulate the rpm's at the transmission input.
I still don't understand how I can tell what I'm getting in a forklift motor. There just aren't really any specs I can find for any given motor. Should I just be looking for a certain size motor with a continuous duty rating?


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## remy_martian (Feb 4, 2019)

etek...


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## cricketo (Oct 4, 2018)

I googled etek, the only stuff that popped up looked like Motenergy. Either way, I have two ME1004 motors in similar implements, one in a Husqvarna riding mower. The main thing about it is that it's designed to put out some 3000RPM at 48V, it would be perfect. It has a PM rotor, so it is indeed quite a bit lighter than a forklift motor, but the weight can easily be added if necessary.


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## palmtree (Jul 14, 2016)

If budget wasn't an issue then the me1004 would be perfect. For one thing, it is nice to have all the necessary specs available.


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## cricketo (Oct 4, 2018)

are you planning to obtain a free forklift motor ?  Unless you can get one locally for the price of scrap, I don't see how ME1004 would be much different. Consider the fact that shipping a forklift motor will be a pretty penny, where a permanent magnet motor would cost just $30-40 to ship.


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## electro wrks (Mar 5, 2012)

cricketo said:


> I googled etek, the only stuff that popped up looked like Motenergy. Either way, I have two ME1004 motors in similar implements, one in a Husqvarna riding mower. The main thing about it is that it's designed to put out some 3000RPM at 48V, it would be perfect. It has a PM rotor, so it is indeed quite a bit lighter than a forklift motor, but the weight can easily be added if necessary.


This motor has a PM _stator_. Palmtree, pull off the red/orange cover(if that's what it is) on the input for the transmission. There could be a opening to accept a splined or keyed shaft. This is what you would have to fit the motor shaft into for a direct drive.


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## cricketo (Oct 4, 2018)

electro wrks said:


> This motor has a PM _stator_. Palmtree, pull off the red/orange cover(if that's what it is) on the input for the transmission. There could be a opening to accept a splined or keyed shaft. This is what you would have to fit the motor shaft into for a direct drive.


You are correct! It's a brushed motor, so definitely a PM stator. I was just servicing another Motenergy motor (ME0201014201) which is a BLDC, and it had a PM rotor so I confused the two.


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## floydr (Jun 21, 2021)

palmtree said:


> If budget wasn't an issue then the me1004 would be perfect.


I picked up a tennant motor 24v-72v 100A continuous for cheap on ebay, It looks to be a slightly derated ME0709. That I am planning on using for my tractor conversion.
later floyd


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## remy_martian (Feb 4, 2019)

Hey Floyd - what model number on the motor?


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## floydr (Jun 21, 2021)

Part #1200569
closet thing to a model number on the motor


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## cricketo (Oct 4, 2018)

floydr said:


> Part #1200569
> closet thing to a model number on the motor


Yeah, that looks like the floor burnisher part number. Based on the pics it seems to be a Motenergy motor, must be OEMed.


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## palmtree (Jul 14, 2016)

Any opinions on this motor? Drive motor from 6000lb crown pallet jack. I'd like to run it at 48v but I'm not sure it's enough power.


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## cricketo (Oct 4, 2018)

palmtree said:


> Any opinions on this motor? Drive motor from 6000lb crown pallet jack. I'd like to run it at 48v but I'm not sure it's enough power.


1.5kW at 24V is 62.5A. If you double the voltage, you will get 3kW continuous - seems like still quite far from your target.


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## palmtree (Jul 14, 2016)

Ya that's what I was thinking. Just seems crazy that my little tractor would require the same size motor as a road going car.


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## cricketo (Oct 4, 2018)

palmtree said:


> Ya that's what I was thinking. Just seems crazy that my little tractor would require the same size motor as a road going car.


I don't know if it requires it. You probably would get away with slight downrating, but how much does a "road going car" take ? I googled just now a Toyota Corolla - 139 to 169 HP, so over 10 times more than what you're looking at.


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## palmtree (Jul 14, 2016)

Right, but how many ev conversions have you seen done with 9" to 11" forklift motors? Seems like most of them. By the way, I can't seem to find any 9" forklift motors -- they all seem to be larger.


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## cricketo (Oct 4, 2018)

Here is the name plate from my forklift motor (still on the forklift ) :









It doesn't say what amperage it's rated for, but the system is fused at 400A, so I imagine at least 300A is expected. It is currently on a 36V battery, so 11kW or so. Then from that you can calculate the power if you were to bump up the voltage in a conversion like people do...

Forklift is 5800lb with 4000lb lift capacity.


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## palmtree (Jul 14, 2016)

How big is that motor?


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## cricketo (Oct 4, 2018)

palmtree said:


> How big is that motor?


I want to say it's 10-11", but I can't get to it at the moment to measure. NOT SMALL for sure. Anyway, my point was that those big lift motors can deliver quite a bit of power under increased voltages given their current ratings.


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## palmtree (Jul 14, 2016)

Ya I understand what you mean. I see how the big motors can apply some real power. I'd like to find a 7" or so that can handle 200 amps. Then I'd be looking at almost 10kw peak which would be more than enough for me. I just wish it wasn't so difficult to find the specs on these things.
Is yours for a car build?


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## cricketo (Oct 4, 2018)

No, that motor is in a working forklift which I need as a forklift  But I do have another motor to show off, I will make a picture of it in a few


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## palmtree (Jul 14, 2016)

I have this one available too but it's almost 11" in diameter. Any way to know what kind of juice I could run through this?


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## cricketo (Oct 4, 2018)

That's a Peerless-Winsmith I pulled out of a boom lift. Extremely heavy, and note it's only 7HP while being rated for intermittent duty.


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## cricketo (Oct 4, 2018)

palmtree said:


> I have this one available too but it's almost 11" in diameter. Any way to know what kind of juice I could run through this?


Some other folks may have a better answer to that, but personally I wouldn't hesitate to ramp it to 200-300A, especially if you add/use a temp sensor and cut back on overheating.


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## palmtree (Jul 14, 2016)

cricketo said:


> View attachment 127143
> 
> 
> That's a Peerless-Winsmith I pulled out of a boom lift. Extremely heavy, and note it's only 7HP while being rated for intermittent duty.
> View attachment 127146


Are you not concerned about the fact that it is rated for intermittent duty?


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## cricketo (Oct 4, 2018)

palmtree said:


> Are you not concerned about the fact that it is rated for intermittent duty?


I was showing you that motor just for the scale reference. Series wound motors just happen to be big and heavy while delivering little power compared to PM motors whether AC or DC. This specific motor I replaced with AC-23 in that machine, I don't have any upcoming projects for it.


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## palmtree (Jul 14, 2016)

cricketo said:


> I was showing you that motor just for the scale reference. Series wound motors just happen to be big and heavy while delivering little power compared to PM motors whether AC or DC. This specific motor I replaced with AC-23 in that machine, I don't have any upcoming projects for it.


Did you replace it because it was unreliable or not working well?


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## remy_martian (Feb 4, 2019)

I don't understand why you need so much power to tow a roller. Is it round or rectangular? Towing at 30MPH?

More than 4 or 5 kW on a reduction chain/belt will just spin the tires.


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## cricketo (Oct 4, 2018)

Machine kept burning the controller, and I wasn't sure if there was an issue with the motor or my style of use was just outside of its capabilities. So I after I replaced the controller twice, I decided to decouple the drive into a separate system with a much more powerful motor. So original system had two motors - one drive motor, shown above, and another for hydraulic pump, while a single controller flipped between the two using contactors. Now the original controller only handles the pump motor, while the drive is on independent motor and controller.


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## palmtree (Jul 14, 2016)

remy_martian said:


> I don't understand why you need so much power to tow a roller. Is it round or rectangular? Towing at 30MPH?
> 
> More than 4 or 5 kW on a reduction chain/belt will just spin the tires.


I don't know either. I'm just going by the fact that the original engine was 12hp to 18hp depending on the model. That would be somewhere around 9 to 13kw. I know that electric motors provide more low end torque but I don't know how much different it would be.


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## remy_martian (Feb 4, 2019)

But you aren't running any implements off the PTO...


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## floydr (Jun 21, 2021)

palmtree said:


> Any opinions on this motor? Drive motor from 6000lb crown pallet jack. I'd like to run it at 48v but I'm not sure it's enough power.


If you overvolted it to 60v you would almost have 4kW 3720w about 5hp although I doubt it is a continuous rated motor especially with the overvolting.
later floyd


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## Frank (Dec 6, 2008)

Remember that motor ratings are typically Continuous and ICE ratings are Peak. But a bigger motor won't heat up as much. You can typically go quite high on voltage with brushed motors but you wouldn't need to. My Electrak is a 36V system and while I only use it cut grass these days, for many years I also moved snow with it. I don't know how much current it draws but I'll bet max output's in the 2-4 HP range.

Oh - for inspiration: 




John's gone now but he always had an interesting perspective on things.


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## Frank (Dec 6, 2008)

This article discusses his tractor in more detail (near the bottom) and gives some operating parameters: Mother Earth News


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## Mick Delaney (Sep 25, 2008)

Not sure if this helps, I had a GT3000 with an ME1004 for many years. it was a 48V system, with an Alltrax controller. 
It would pull about 20A tooling around with a small trailer. It had no problems moving a heavy load - it could tow our water trailer (5000lbs) around, but traction was a problem on anything but flat. 
One mistake I made was to put the batteries up front - it made steering very heavy. 
Good luck with the project!


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## cricketo (Oct 4, 2018)

This is mine during early testing:









It works, but not the most efficient setup due to hydrostatic transmission and the belt/pulleys. Eventually I want to shove a Chinese transaxle with a motor onto it, and keep the front motor for running the deck only. No motor controller used - motor runs straight from the battery, which reduces the cost of the conversion.


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## brian_ (Feb 7, 2017)

Frank said:


> Remember that motor ratings are typically Continuous and ICE ratings are Peak.


But that's not true. Electric motors are routinely rated according to various non-continuous duty cycles.


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## Electric Land Cruiser (Dec 30, 2020)

palmtree said:


> I don't know either. I'm just going by the fact that the original engine was 12hp to 18hp depending on the model. That would be somewhere around 9 to 13kw. I know that electric motors provide more low end torque but I don't know how much different it would be.


I think part of the reason you are having trouble finding the right motor is because you are focusing on the wrong things. The original ICE engine has 12hp but that is not directly comparable to an electric motor.

Horsepower is a function of torque, so what you really want is an electric motor that makes 12hp at 3600 RPM. That is about 18 ft-lbs at 3600 RPM.

Motors are rated for an RPM usually at a certain voltage. More voltage more RPM, less voltage less RPM. So a secondary consideration is if you pick a motor that has a maximum RPM at a certain voltage, then when the battery is low the maximum RPM will also be lower. So you want to pick a motor/battery combination that will allow you to have a full range of usable power through the full range of usable battery voltage.

Also note that maximum RPM is also a lot of time rated with no load on the motor, so if you add a load the RPM will be lower.

I would also open up the idea of 72 or even 96 volts. More voltage more RPM more area under the curve to get work done. Less current less heat and faster charging are also benefits.


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## remy_martian (Feb 4, 2019)

That 12HP ran a PTO for things like a mower deck and provided traction power. He is not running implements, so the gas equivalent is no more than my 3HP minibike was to move rider and tractor.

Now add in the rolling resistance of a roller and his harrows and he's at around 5-6HP GAS engined.


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## 57Chevy (Jan 31, 2020)

What your kW requirement is depends on force x distance at speed, i.e. if you are pulling a scraper or some implement then the force is much higher than a trailer full of dirt. Choose your motor power and the cooling/duty cycle based on your worst case load and desired speed requirement. Combine with desired operating time at that load gives battery capacity required. Volts and Amps are the same as torque and rpm, and also force x speed, once you have added in efficiency of each energy conversion and assuming you aren't going up and down hills. Time converts from power to energy and therefore gives run time from the amount of work available in the battery. Spreadsheet time

One of the simplest ways of working out energy use is to monitor gas consumption, if that is an option still.

Lets say you settle on a 5kW electrical power brushed series forklift motor, you'll be rejecting about 1kW of heat under full load, enough to heat a bedroom comfortably in mild winter. Spending a hundred times that on an more modern AC motor you'll need to reject 300-400W. Choose your cooling based on your expectations of run time vs cooling time vs average load vs budget. Engineering


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## cricketo (Oct 4, 2018)

57Chevy said:


> One of the simplest ways of working out energy use is to monitor gas consumption, if that is an option still.


Using which efficiency numbers ?


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## 57Chevy (Jan 31, 2020)

10% would be a good rule of thumb for a small engine.


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## brian_ (Feb 7, 2017)

57Chevy said:


> One of the simplest ways of working out energy use is to monitor gas consumption, if that is an option still.





57Chevy said:


> 10% would be a good rule of thumb for a small engine.


10% seems pessimistic to me, although it might be a reasonable approximation. Specific fuel consumption (amount of fuel consumed per unit of shaft energy produced) is readily available for many engines. I couldn't find a BSFC chart for any small engine in a quick seach, but some list consumption at rated power, such as a Honda GX160 consuming 1.4 L/h at 3,600rpm to produce 2.9 kW - that's about 0.5 L/kWh (or 0.5 L/h or 0.13 US gal/h per kW of output). In mass terms, it's roughly 360 g/kWh or about 23%. Consumption will be better at lower speed and full load, and worse at part load.


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## palmtree (Jul 14, 2016)

Thanks for all the advice. I can get the pump motor for $100 or the 11" drive motor for $200. Both out of an old Clark EC500 forklift. I'm tempted to go with the big one but I'm afraid the RPMs will be pretty low at 48v.


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## 57Chevy (Jan 31, 2020)

brian_ said:


> 10% seems pessimistic to me


yup, just a rule of thumb, average eff at optimum load won't be equal to total eff etc. A five minute google comes up with this graph


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## brian_ (Feb 7, 2017)

57Chevy said:


> yup, just a rule of thumb, average eff at optimum load won't be equal to total eff etc. A five minute google comes up with this graph
> View attachment 127372


Yes, but running at half power in the cases shown in that graph only lose about 25% of peak efficiency... getting down to 10% means starting really low. That paper studies some very low compression ratios in a research engine, with the point being to compare compression ratios and fuels, rather than to represent typical commercially available engines.


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## 57Chevy (Jan 31, 2020)

Your average Briggs n Stratton is 6:1 c/r... anyway, getting off topic


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## brian_ (Feb 7, 2017)

So assume 400 g/kWh, and if the engine is less efficient than that the resulting power calculated from fuel consumption will be higher than necessary, which is better than under-sizing the motor.


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## remy_martian (Feb 4, 2019)

palmtree said:


> Thanks for all the advice. I can get the pump motor for $100 or the 11" drive motor for $200. Both out of an old Clark EC500 forklift. I'm tempted to go with the big one but I'm afraid the RPMs will be pretty low at 48v.


What do you need RPM for?


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## palmtree (Jul 14, 2016)

3600 rpm is recommended. I'm sure that's mostly for mowing which I don't plan to do. It'd be nice to keep the capability though. It also has a shaft to run a front snow blower so you never know....


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## remy_martian (Feb 4, 2019)

"It would be nice" gets very expensive in electric conversions


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## palmtree (Jul 14, 2016)

Here's where I'm at. Semi-locally I have the following to choose from:
11" x 16" 200lb drive motor.
8" x 16" 100lb pump motor.
8" x 7" floor polishing motor.

Pics attached.


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## cricketo (Oct 4, 2018)

That floor polisher motor looks like a Motenergy motor. I think it's the best option.


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## floydr (Jun 21, 2021)

Probably an OEM for Tennant/Nobles Like the motor I have. Was wondering if you have a coupler in mind? How did the original motor drive the transmission? 
Later floyd


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## palmtree (Jul 14, 2016)

The standard shaft for GRAVELY riders is 1.125" diameter, approximately 3.75" long, 1/4" keyway and a 7/16-20 tapped hole in the end of the crank. I may end up with a short chain drive. Then I could manipulate the RPMs if needed.


floydr said:


> Probably an OEM for Tennant/Nobles Like the motor I have. Was wondering if you have a coupler in mind? How did the original motor drive the transmission?
> Later floyd


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## floydr (Jun 21, 2021)

if you do go with the floor polisher motor The shaft is most likely 3/4" 1/4" keyway looks to be a 1.25-1.5 inches long on mine with a 1/4"- 5/16" tapped hole in end of the crank too early in the morning here to accurately measure he shaft mine. Looks to be a nice motor
later floyd


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