Electric drive motor specs

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Glenn Brooks
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Electric drive motor specs

Post by Glenn Brooks »

Hi All,

I recently acquired a pair of wheelchair DC motors and drives to repower an old (12” gauge ride in) center cab electric.
However, I can’t find ANY Horsepower or wattage specification for the motors, anywhere. No face plate, nothing on line, no info from the distributor, nothing in the owners manual.

Can anyone advise what power range these motors MIGHT be.

Model: PM 805-D09A and D09B (right and left motors) marked CIM 808-077a 22 v DC

Note these are old units, possibly replacement for the Permobile 300 series motors.

I really like to determine if they are actually powerful enuf to drive my loco before fabricating mounting brackets and buying sprockets and chain...BTW, the loco is large scale and bulky, not not particularly heavy - probably under 500#. I do want to be able to pull a gross train weight of around 15,000-20,000#

Thanks much,
Glenn Brooks
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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John Hasler
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Re: Electric drive motor specs

Post by John Hasler »

What are the dimensions? Comparing them to motors of similar size and known ratings can get you a rough estimate of the power. You can also measure the top speed, the armature resistance, and the stall torque.
jcbrock
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Re: Electric drive motor specs

Post by jcbrock »

Glenn, my poking around makes it look like they are possibly in a Permobil C500. Going to the Permobil website it looks like the C500 has a 63a circuit breaker, so with 2 motors would likely be a max of no more than 30 amps (if that). That'd be around 1300 watts total.

As a data point I think my 4x450 watt, 850 lb loco is able to pull 4000 lbs (including itself), but I don't think it could come close to 15000 lbs, and I know I couldn't get it stopped without train brakes.
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Glenn Brooks
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Re: Electric drive motor specs

Post by Glenn Brooks »

John, that makes sense, I did find a mention of two circuit breakers in the owners manual that identified either 63 amps, or 80 amps. But, no explanation which fit these motors. That would make these around 500 - 600 watts, I guess.

My 20,000# max load is a fully loaded 5 car industrial grade consist. Minimum need would be just the the loco and engineer - so 1000# or so max.

If I put one of these motors on each axle, possibly could achieve 600 x 4= 2400 watts. Or with 1500w x 4= 6000 w

So this is beginning to look very doable. Thanks!
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Steggy
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Re: Electric drive motor specs

Post by Steggy »

Glenn Brooks wrote: Thu Oct 08, 2020 11:47 pm John, that makes sense, I did find a mention of two circuit breakers in the owners manual that identified either 63 amps, or 80 amps. But, no explanation which fit these motors. That would make these around 500 - 600 watts, I guess.

My 20,000# max load is a fully loaded 5 car industrial grade consist. Minimum need would be just the the loco and engineer - so 1000# or so max.

If I put one of these motors on each axle, possibly could achieve 600 x 4= 2400 watts. Or with 1500w x 4= 6000 w

So this is beginning to look very doable. Thanks!


Just remember the old engineering adage: Use enough gearing, you can make a washing machine motor move a bulldozer. :D
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SteveM
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Re: Electric drive motor specs

Post by SteveM »

BigDumbDinosaur wrote: Fri Oct 09, 2020 12:59 am Just remember the old engineering adage: Use enough gearing, you can make a washing machine motor move a bulldozer. :D
“Give me a lever long enough and a fulcrum on which to place it, and I shall move the world. ”
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Glenn Brooks
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Re: Electric drive motor specs

Post by Glenn Brooks »

Hey guys,

One more question. Is there any way to estimate battery life relating to total weight of the train?

I know a lot of electrics run all day at Train Mountain. But these usually are just the loco and one or two lightly loaded cArs.

Wondering if 6-8 hrs operating time/day with electric drives is feasible with a 12000 to 20000 pound train?

Thanks
Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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Pontiacguy1
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Re: Electric drive motor specs

Post by Pontiacguy1 »

I think that you are a bit mis-matched when it comes to locomotive size/weight vs. trailing tonnage. You say that your locomotive will only weigh 500-600 pounds or something like that, but you want it to handle a 10,000+ pound train. I don't think that is realistic. you are not going to have enough tractive effort. If you are going to have your train pull 10,000 pounds, then just the motors and batteries by themselves are probably going to weigh well in excess of the 500-600 pounds. Add in that you want an 8 hour battery life, and you'll quickly see that what you are wanting to do with your locomotive is likely not feasible in that size/weight envelope.

For example, we have small-ish towmotors where I work that run off of 36 volt electric power. They can run about 10 hours between charging and they can lift approximately 4,000 lbs, travel at 8 MPH, and the empty trucks weigh about 8,000 lbs each. The battery that is in these things weighs 2,300 lbs, and is about 2 1/2 feet by 4 feet by 3 feet. It has a triple-aught power cable coming out of it. Granted, this is not an apples-to-apples comparison, but to do what you are wanting to do, it's going to take a lot higher power and a lot more amp-hours worth of battery than you are likely going to be able to fit in your chassis.

Maybe I'm just out in left field. Maybe I just missed some piece of information that would make this make sense to me.
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Re: Electric drive motor specs

Post by Steggy »

Pontiacguy1 wrote: Fri Oct 09, 2020 10:53 amI think that you are a bit mis-matched when it comes to locomotive size/weight vs. trailing tonnage...

I find myself agreeing with this.

Assuming a train weight of 20,000 pounds, the drawbar pull required to balance the train on a one percent grade will be 200 pounds. If the train is running on dry and clean (i.e., not rusted) steel rail, we can figure on a 25 percent factor of adhesion, best-case. The weight on the drivers would have to be at least 800 pounds to produce the adhesion required to produce those 200 pounds of drawbar pull. If you are on a three percent grade, which is not entirely uncommon in large-scale railroading, now the required drawbar pull to balance the train is 600 pounds, and the required weight on the drivers to maintain adhesion jumps to 2400 pounds.

However, that only prevents the train from rolling back down the grade. If you are expecting forward motion :D your loco will have to develop proportionally higher drawbar pull and thus would have to be that much heavier to maintain adhesion. I think you can see where this is going.

Given the propulsion requirements to move a 20,000 pound train, I think your locomotive as described will not be feasible in battery-electric form. The big issue will be battery capacity versus required sustained power output over the desired six to eight hour operating period. Unless you were to go the lithium-ion route (costly and almost unobtainable in the sizes you would need), you are limited to deep-cycle type lead-acid batteries...lots of them.

Sealed lead-acid batteries of the type used in uninterruptible power sources are better able to sustain a long discharge than conventional deep-cycle batteries, but are two to three times as expensive as the latter. Either way, you would be hooking up a lot of batteries in series/parallel to get the required amperage (very high) to start the train and sustain a drag up-grade. My opinion is the battery mass required to propel your train at anything above a snail's pace, and do so for six to eight hours, will likely be larger than the locomotive itself—and substantially outweigh it.

Also, the traction motors you mentioned earlier are too lightweight for the expected loading. Given the expected train weight and using the power-to-weight ratio typical of full-sized work trains, you would need about 20 horsepower at the wheels to assure you can maintain a reasonable pace on an ascending grade. In this application, shunt-wound or permanent magnet motors would likely fall short; they may be able to propel the train once it is moving, but not be able to start it. Good luck on finding a series-wound motor with the required continuous output.

Have you given any thought to powering your loco with an ICE? I may be missing something here, but I foresee a lot of difficulties waiting for you in trying to do this with a battery-electric drive.
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Pontiacguy1
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Re: Electric drive motor specs

Post by Pontiacguy1 »

My thought is that if you are wanting to build this for general purpose use, as a convenient track maintenance locomotive, and even to go traveling with it, your expectations of what it should be able to pull should be downgraded significantly. I would try to pursue a drivetrain that could reasonably handle 2 to 3 loaded cars on a 2.5 to 3% grade, probably around 3000 trailing pounds. then your locomotive could come in around 1000 lbs total weight and an electric drivetrain is completely reasonable to use. Anything much more than that, and I would probably have to convert it to hydraulic drive. Others with more electrical expertise can jump in, but I think that I'm being realistic here. What you are wanting to do with this locomotive is like trying to pull a 30 foot camper trailer with a 1960's VW Beetle. It wasn't designed for that, and it isn't going to have enough weight and power to handle it.
Glenn Brooks
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Re: Electric drive motor specs

Post by Glenn Brooks »

thanks guys, Good comments. I think you guys are right on. I see the mismatch you are mentioning, particularly with tractive effort and weight on drivers needing to be upwards of 2,400#. That would be a large size engine, even for 15” ga. Way bigger than this center cab can accommodate.

Iam thinking about a commercial 15” or 18” ga operation. We have a group interested in starting a park gauge live steam club here in the PNW, so I’ve been thinking about how to donate this and another old barn find to the cause. i think the key here is to determine what the equipment itself is reasonably capable of doing. Which in this case, is considerably less than an ideal, fully loaded, 5 car consist...

So, Couple of clarifications: 500# is current empty weight. pretty sure the fully restored weight could hit 800 - 1,000#, with some structural additions, two banks of batteries, wider guage trucks and motors on each axle, etc. Also, I don’t think the existing frame and body design would accommodate anything more than one or two battery racks and some traction motors on the axles. The hood ends are to small for any decent sized internal combustion motor, or power/hydraulic assembly.

Also, not sure it is worth that much time and effort. So, thinking likely this should remain a backyard trolley, or could become a light weight ROW speeder - keep the electrical conversion to a simple 2 or 4 motors and one set of batteries. That could be more than ample for backyard railroading - hauling maybe 3 -4 cars lightly loaded with neighborhood kids.

This is a real dilemma for Park gauge. 15” ga can do real work. But what does it take to handle a large train weight? Pretty heavy, large size equipment. Larger than feasible for most hobbyists perhaps. More pondering needed, me thinks.

Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
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Re: Electric drive motor specs

Post by Erskine Tramway »

Glenn Brooks wrote: Sat Oct 10, 2020 7:05 pm
This is a real dilemma for Park gauge. 15” ga can do real work. But what does it take to handle a large train weight? Pretty heavy, large size equipment. Larger than feasible for most hobbyists perhaps. More pondering needed, me thinks.

Glenn
Hi, Glenn...

The gas-hydrostatic that we built for Elliott Donnelley to donate the the Quincy Park District, had a four cylinder engine. As I understand it, the oil cooling wasn't up to par, so it had a tendency to run hot. Admittedly, non-steam really wasn't our 'thing', so we didn't have the expertise.
QC 940 builder's photo.jpg
There have been 15" Gauge locomotives built using the modern 3-cylinder diesels, and they seem to work OK. As you say, 15" Gauge is pretty big and heavy, there isn't much way around it.

Mike
Former Locomotive Engineer and Designer, Sandley Light Railway Equipment Works, Inc. and Riverside & Great Northern Railway 1962-77
BN RR Locomotive Engineer 1977-2014, Retired
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