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Discussion Starter · #1 ·
Hello all,
I've finished converting the old 72 cutlass to manual and am looking into motors. I found a 72 volt 11" CAT forklift motor. This is the first 72 volt forklift motor that I've see but I don't know how to find any information on it. A guy is selling it for $600 on facebook marketplace but is unsure if it even works. He said he was going to convert his Chevy S10 to electric but doesn't have time. The serial number is CL42-331 and the part number is 300982. I've tried to find information on the specs of this motor but were unsuccessful and was hoping someone with more experience might point me in the right direction or bestow knowledge on me. I'm also unsure of pricing. Is $600 too much seeing as he doesn't know if t works. I could test it with a battery I suppose. And the most important question is can it move my 3600lbs cutlass at 70mhp? I was originally thinking about using 2 9" or 11" 48 volt motors but if I can just use one, that would be much nicer.

Any help would be much apricated!
 

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Almost certainly it can, yes. An 11" motor is plenty for highway speeds.

You can test if it runs with a 12v starter battery and some jumper cables. No issues there.

$600 seems a bit steep. $600 for an unknown-condition motor is foolish. $50 for an unknown motor is a fair price, if you don't have to drive far to look at it. $200 is more reasonable for a working forklift motor, you should be able to find them at that price anywhere.

You'll want to run your motor at like, 150+ volts if you want to get decent power out of it. Forklift motors handle higher voltages than their original spec just fine. There's a giant thread about it here.
 

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I was teaching a class to a bunch of engineers about some equipment my company had installed, all of which was set up in SAE units. A British engineer was bugging me that we should be using metric units (actually, all the equipment and software supports them just fine - it was this industry's conventions that were mired in SAE). He shut up, amid chortling from the others, when I asked him how many miles he drove to the pub for a pint, and how many stone he'd lost since moving to California. (All units that are currently, and pretty much universally, used in the UK.)

The United Kingdom - inching towards the metric system...
~~
Mark Moulding
 

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I was teaching a class to a bunch of engineers about some equipment my company had installed, all of which was set up in SAE units. A British engineer was bugging me that we should be using metric units (actually, all the equipment and software supports them just fine - it was this industry's conventions that were mired in SAE). He shut up, amid chortling from the others, when I asked him how many miles he drove to the pub for a pint, and how many stone he'd lost since moving to California. (All units that are currently, and pretty much universally, used in the UK.)

The United Kingdom - inching towards the metric system...
~~
Mark Moulding
So Kilograms Sterling as a Brexit metric monetary unit, then?
 

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In case anyone missed my point: determining whether a motor is suitable for a vehicle based on the diameter is odd.
Not if they're all more or less the same length...
And that's the key... not all 11" diameter motors are even remotely similar, but if comparing only brushed series-wound DC motors from low-voltage mobile equipment (forklift trucks, etc), they are all pretty similar in design and proportions, so diameter is a reasonable rough approximation of "size", implying torque and power output potential.
 

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And that's the key... not all 11" diameter motors are even remotely similar, but if comparing only brushed series-wound DC motors from low-voltage mobile equipment (forklift trucks, etc), they are all pretty similar in design and proportions, so diameter is a reasonable rough approximation of "size", implying torque and power output potential.
My lift truck runs on a brushed 36/48 motor (that's how it's labeled, current battery is actually flooded 36v). His motor is rated for 72v. Is the suggestion that if the diameters of the two matched, they would have the same performance ? Or perhaps the emtpy/loaded weight of the truck, and/or current rating of the motor would be more defining indicator of performance ?
 

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Assuming the motors have the same-ish weight...once you saturate the iron, all bets are off.

Running higher voltages will cook the brushes/commutator quicker, so it's not exactly a free lunch.
What I was saying, is that across electric lift trucks that run on brushed motors there is a variety of weight/load ratings that inevitably require different performance from the traction motor. For example, my truck is a bit under 6000lb empty, with lift capacity of about 4000lb (I can pull up the name plate if anyone insists), all while running on 36v. Would a lift truck with the same weight/load rating running a 72v have a different motor diameter ?
 

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Depends on the pump setup and incline spec. But you're asking about the same machine spec. Which implies same HP motor.

For the same HP, the 72V should be a smaller diameter, run at half the current, and spin faster. Not a bolt-in for the 36V because the windings will be smaller. Can the 36V motor work at 72V? Maybe...
 

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Depends on the pump setup and incline spec. But you're asking about the same machine spec. Which implies same HP motor.

For the same HP, the 72V should be a smaller diameter, run at half the current, and spin faster. Not a bolt-in for the 36V because the windings will be smaller. Can the 36V motor work at 72V? Maybe...
Pump setup is irrelevant, we're talking strictly traction - electric lift trucks typically have two motors.

Well, I didn't mean it as a replacement. I meant when you get a fork lift motor for use in a car conversion, the specs of the donor vehicle may indicate better of what the motor will be able to do as opposed to its diameter. I don't want to insist on anything either way, like I said, it just seemed odd to me that people would drive conclusions based on the diameters [alone].
 

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That's the way it's been, and so forever shall be written 🤓

Yeah, you're right.... now that I think about it, the pump motor is a separate thing that makes a loud racket during lifts. I only drove one for a few years, lol.
 

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Traditionally diameter of the motor gave a rough estimate of available torque. Therefore a larger diameter should be more powerful at a given wattage. It also caused you to deterimine if it was a hydraulics motor or the main drive. Most pump motors have a female splined shaft which is useless for auto use unless you go and make a custom output shaft.

Having said that, it is worth noting that a prepped ADC9 produces as much torque as my 13" Kostov but for not as long.
 

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Discussion Starter · #17 ·
Hello all and thanks for the input. So if dia is only the start of identifying if a motor will work, what are the next steps? Does anyone know where I might find performance specs on this motor or any motor for that matter? And I asked the guy if he would drop the price to $200 and he said its worth $600 as is and wouldn't budge. I also found a 10" forklift drive motor but its only a 48 volt though they only want $100 for it and it appears to have either a 9" hydraulic pump motor with it or maybe another drive motor. Its hard to tell by the photos. Has anyone ever joined two different sized motors together?
 
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