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Discussion Starter · #1 ·
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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Discussion Starter · #3 · (Edited)
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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Discussion Starter · #8 ·
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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Discussion Starter · #11 ·
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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Discussion Starter · #26 ·
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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Discussion Starter · #30 ·
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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Discussion Starter · #37 ·
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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Discussion Starter · #40 ·
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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Discussion Starter · #54 ·
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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Discussion Starter · #60 ·
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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Discussion Starter · #62 ·
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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Discussion Starter · #65 ·
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.
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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