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Looking for more info on 2 motors

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Hello I'm new here and have 2 motors i pulled from an older, but functionally working forklift. I'm hoping someone may be able to identify and help me to get an idea what these could be repurposed to do. The larger one is a:

(1) Prestolite part # MKB 4004, 48 volt, (ser#?) 20 300 9289 36 (1st 7 pictures)

(2) Porter/ Peerless , frame DPM56DG4, 183-18-0755-0 ,48volt, 1 3/4 hp, P.M winding, 35 amp, 2000 rpm, duty-Int. ,ser# UJ30695 (Last 3 pictures)

That's all the data I have, although I have more pictures, just trying to make info less confusing. In hours of searching I have yet to find exact same units to glean more info from, any help would be appreciated.....Rick


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7,793 Posts
Hi Rick,

2 pretty nice motors looking in great shape. The big downside is they are both pump drive motors. I'm sure the Prestolite MKB has an internal spline drive for pump shaft, 9 tooth. I suspect the Porter also has no shaft extension. This is a major stumbling block for second life as EV propulsion.

Both are unidirectional in application with pumps. The Porter being PM is easily reversed with polarity swap. The MKB is series wound and requires internal mods to reverse. It also has the standard factory advance, 4.5°.

I think the Porter is nice and would be great for light duty and smaller EVs like bikes, carts and yard tractors. Likely can tolerate a bit more voltage but not a lot.

The MKB is a monster in my opinion. You don't see many of these. It has a long commutator with 12 brushes. That's more brush contact area than a Warp11. And that relates to inrush current tolerance. Like at launch in a dragster. I'd love to see this in that Jr comp dragster on the other thread paired with a Z3kA controller. Actually for normal EV duty it may have too much brush and difficulty filming properly.



· Registered
2 Posts
Discussion Starter · #3 · (Edited)
Hey Major, thanks a lot for your insight, I'm now very glad I took the time to pull these and other items from that old forklift. While the possible applications sound really exciting I'm backed up for next 2 years worth of projects, these motors should be used by someone who's already got the itch to have fun with them. I'm glad I didn't let it get destroyed for pocket change. Here is how I ended up with them....someone I know asked to borrow a 10k lb capacity trailer from me to haul some "Scrap" the next day. On the way over (9:30 pm)to dropping it off at at his very run down former factory (closed 5 years ago) I could only remember his OLD 3/4 ton Pickup and wondering if this trailer is overkill for him. Reluctantly I ask about it, he shows me his old forklift that looks hardly used, he left outside (Minnesota) and not moved for 3-4 years, says Lead acid battery (completely destroyed) alone maybe near a TON, the F-lift "about" another 2 OR 3 tons....(just then I remember some previous hair brained ideas he's had) says junk yard promised him .14 # for battery/ .06 # for rest. He 'hired' a mobile crane for the morning to lift everything onto my trailer.While inwardly kicking myself for be involved, I briefly contemplate giving him the $300 and part it out there in my 'spare time' for $5K return, might be preferable to a $1000 of damage and mayhem to my trailer that I'll Never recoup. I quickly decided not to become any major source of income to him and offer him 0.10 a pound for items I can remove that nite to help me complete parts list needed to finish my 3 ton vehicle high lift project. Ended up with all the forklift electrics, most of hydraulics ...took me 5 hours and cost me only $80 but... was VERY messy, HE hadn't even thought to drain the fluids....7 gal old battery acid and 7+ gal of hydraulic fluid. Sorry the story so long, thought It would give someone a chuckle. Life is stranger than fiction.
Ya know in the past I've successfully welded oversized shaft extensions and had a shop lathe turn them true, i wonder if that's possible with these type of motors?
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