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Choosing a motor.....sigh.

4394 Views 7 Replies 5 Participants Last post by  gottdi
Hey all,
I have given it a try to read all of the 136 pages of the sticky on choosing a forklift motor. Honestly, to me it's too much. There is good stuff in there, but after fifteen pages, I'm just skimming. Another ten pages, and I'm jumping to random pages hoping to find some life changing monumental slice of pie (I like pie, Key Lime last night).

Is it possible to create a record/list of the motors that are in successful use? Say something like the motor make, model, serials, frame, HP, RPM, any other relevant information on where or what these came out of or from?

Been web searching used DC motors, came across these two sites Thoughts or recommendations?
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if you start looking thru the 'garage' on site here, you'll find a LOT of Advanced DC (DC) 8", 9", a lot of Netgain (Warp/impulse)8". 9", and a fair number of Kostov (11"/13").

forklift motors are for sure a low cost option, but you may end up needing to rebuild them, advance for higher EV voltages, replace bearings, etc.

The sticky if very full of a lot of conversation now and a few questions and answers. I appreciate it is hard to wade through but now most people simple post up their donor motor and ask questions there.


Look for a motor that is around about 9"-11" diameter and around about 12"-17" long.
It should have four terminals so that the field and armature terminals are separate. That allows you to change the direction it roates to suit your use.
If you can see the coils then the feild coils should have very few turns of very heavy copper conductors, almost like flat bar then wires, that will confirm it is a series motor.
The comm should have bars that are 2"-3" long with four sets of brushes. The brushes can be large single or twin brushes in each brush box.
There should be a lot of comm bars, around 40s to 60s in number.
The motor should have a male shaft at the drive end. A plain shaft with keyway is easiest to work with but you can use a splined shaft. If it is splined it is helpful to grab whatever gear or drive member that was on it.
A shaft at the comm end can be helpful for driving a tach or PS pump.

Look for the motor plate, the information will be helpful for major to tell you what the motor is like, he is a mine of information.
Go for a higher voltage, 48V to 80V is good as it will allow you to run a 72V to 144V pack, 24V to 36V is a little low but might be usable at slightly lower voltages. It will limit maximum potential speed.
The rest of the data may tell you the design speed, amps, power and insulation. H class insulation will allow the motor to run hotter before the insulation gives up.

If the motor has an internal fan then it can cool itself mostly. If not then look for holes at the ends where a blower fan can be used to force air in. A completely sealed motor may over heat as cooling could be a problem.

When looking at the forklift tend towards those that are front wheel drive. The rear drive three wheel lifts then to have a powered and steering wheel assembly and are smaller. However it may still be worth a look anyway.

The front drive ones come in three flavours.
One type has two motors, one for each wheel.
Another type has a motor built into the axle like a giant golf buggy axle, see my trike thread for the one I bought. The motor may not have a drive end (DE) cap and bearing carrier so it will need to be made from scratch so look carefully to see what it has.
Another type has a conventional looking heavy truck axle and is connected to the motor by a short prop shaft with UJs. That easiest to remove and easiest for direct drive to a rear axle.

If possible see the motor running. If not test the motor, when removed, with no more then 12V to see if it spins.

If you find one take lots of photos of the motor and post details from the motor data plate and maybe the forklift plate too if there is one and those who know more then me can offer specific advice.

Good luck on your motor hunt. :)
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9" 11" and 13" motors are the most used size.

GE Motors are great motors. If it needs bearings replaced it is not difficult. If the commutator is good then you may want to change brushes. Blow out a used motor to clean it of dust.

Warp9" Impulse and ADC 9" motors are pretty much the same thing.
Warp9" are more robust and built specifically for EV's.
Warp motors are now the must have if you have the money to buy them.

Kostov Motors are again in the game and they also have a HV series of motors and they are available. They all have interpoles and are excellent motors. The 11 HV Kostov is a competitor for Warp11 HV. Kostov is the cheaper in cost motor but still an excellent motor.

If you use a forklift motor it is best to find one that is clean and has a keyed shaft instead of the splined shaft. Splined shafts are usable but require a bit more work when designing a coupling system for your vehicle but not a deal killer. A reasonable size for most vehicles is 9". I used a 9" GE in my Ghia and it fits just fine and has the power. I'd not go with any thing under a 9" motor.

Pete :)
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recognizing what I am about to ask:
would it be possible to clean up the sticky, repost, and then close to further comments?

TONs of great info, but I believe it has gotten a wee bit unwieldy.
Let me give a rough idea. You want a motor with bearings at both ends. Some motors rely on what they are turning to support the other end. You want a motor with >30 commutator bars so it has a good chance of tolerating >100 volts. You want about 100 pounds of motor for a 2000 lb. car (finished conversion weight, remember lead is heavy.) This should scale up or down with vehicle weight and is flexible, a ball park that can be fudged depending on performance and range expectations and what is available.
8" ADC is plenty for the smaller cars like geo metro/suzuki swift, especially at 120v. In fact the 8" fits easily, and 9" starts interfering w/ motor mounts. Also has a nice high top rpm around 5k.
Yes, you need to know what fits and what does not but the vast majority of motors are the 9" size. My preference is 9". I actually have a 7 1/2" Starter/Generator motor that will work OK in a buggy given enough cooling air. But for plain old grunt a good 9" or larger is the way to go.

Pete :)
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