Electric drive motor specs

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Steggy
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Re: Electric drive motor specs

Post by Steggy »

rkcarguy wrote: Wed Oct 21, 2020 1:05 pmOh, and one more FYI. Right angle drives can contain worm gears which DO NOT spin down when the power is cut to the electric motors driving them. As a result, if they are used in a large scale train application and the throttle is chopped, all that rolling momentum in the train gets turned into lateral forces on the worm gear drive which blows the gearbox apart (or the wheels lock up and the train slides).
Hence one of the reasons I wouldn't do it with a wheelchair motor.

BTW, worm gear drives can be made to be reversible. An example of this fact with which you may be familiar is the recirculating ball steering gear that was widely used in automobiles before rack-and-pinion became popular.

Reduction in a worm drive is defined as N ÷ S, where N is the number of teeth on the worm gear (the one driving the output shaft) and S is the number of starts on the worm pinion. In most production gearing, N will be 1, 2 or 4. A worm drive with a four-start worm is generally reversible and would work as gearing in a model locomotive. Using a 30 tooth worm gear and a four-start worm, a reduction of 7.5:1 would be produced and the gear train would be reversible.

Another right-angle solution is helical gearing with a 45 degree helix. Two gears of the same helix direction can be mounted on perpendicular, non-intersecting shafts to produce a reversible, right-angle drive. This is the gearing used in Tolo-Matic's shaft-mounted gearboxes. However, a reduction greater than about 3:1 is generally impractical due to the significant sliding action between the teeth.
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Glenn Brooks
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Re: Electric drive motor specs

Post by Glenn Brooks »

Finally made a connection with the Seattle Electric Vehicle Association. Also found an online DIY EV forum. Looks like the small 5 kw forklift motor route might work. Lots of discussion about feasibility of using these type motors, albeit the larger ones. The 7.5 hp motors (5Kw) are doable for small cars, but generally thought to be just a bit on the low end of the scale. So looking perfect for 12” gauge trains. As we have been discussing, the trade off is cost and weight of all the batteries one needs to put onboard achieve the necessary range and endurance.

A side note: found that cost is prohibitive for new 9” drivers and axles, so now thinking about scaling back to the minimum of one powered truck, and a couple of batteries, with the loco and trucks as is, just to get the loco powered up. Then testing its lower theoretical tractive effort against what it will actually pull. If it works out as it should, then consider powering the other truck and loading a larger battery pack for range and speed improvement. This option is much more doable from a cost perspective. Also a lot quicker to get done.

Ryan and BDD, thanks for your comments on right angle drives. I didn’t intend to use Tesla parts, but was interested in the used automotive battery pack market. Your comments on right angle drives are particularily right on. As I’ve been thinking, how could I build a right angle gear set up to transfer power from a single larger motor and one for and aft line shaft down to two rotating trucks.

Ryan, I like the idea of an electric B Unit. - loaded with batteries, extra powered trucks - were talking mainline freight hauler here!

Also prices a used forklift battery pack for sale down in California yesterday. Came in at around $2000, with a one year guarantee. Weight around 600#. 20 hour Amp hour rating comes in at 500 amps! To much money for a yard goat experiment. But, maybe feasible for a full on re-build.

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rkcarguy
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Re: Electric drive motor specs

Post by rkcarguy »

I think if I was going to go electric drive I'd probably put a big generator in a B-unit and use it to drive a pair of high voltage motors.
Wheels are a huge problem for cost in grand scales, one of the other reasons I went with my odd 1/6th scale is I can use 1" plates we can laser cut from remnant plate.
$2000 is quite a bit, probably a lot of shipping included in that and I doubt its anything special. I'd be more inclined to purchase a 2nd hand Tesla pack or a bank of deep cycle batteries. One of the EV guys whose brain I was picking years ago said to go someplace with lots of batteries, take a voltmeter, and pick batteries with the closest to each other "settle voltages".
John Hasler
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Re: Electric drive motor specs

Post by John Hasler »

Glenn writes:
As I’ve been thinking, how could I build a right angle gear set up to transfer power
from a single larger motor and one for and aft line shaft down to two rotating trucks.

ATV differentials and drive shafts?
Pontiacguy1
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Re: Electric drive motor specs

Post by Pontiacguy1 »

I think your idea to get one of these 5KW motors and power one truck is a good one to start off with. Just make sure that your controller is big enough to supply the motor, and that you can use more than one of those controllers together, so that if/when you do decide to power the other truck, it will be a very simple retrofit. I think that once you see how smooth and convenient it's going to be, then you will start working on the other parts pretty soon.

Also: I would avoid used batteries, especially the used battery packs out of Hybrid and electric vehicles. I would also avoid the rebuilt battery packs for those vehicles. Sometimes these things can have some significant age on them, and the "rebuilders" only change out the cells/batteries within that pack that test bad. Thus, most of the batteries in that thing are going to be old and subject to fail at any time. A New battery pack for a small hybrid car can cost $5,000 on up, and it's tempting to go for the "rebuilt" one that can be about $1,800 or so. Problem is going to be that most of the time those rebuilt ones will only last 2 or 3 years before they are in need of rebuilding again. Used Lead/Acid batteries can be the same way. The plates are sulfated enough that they don't deliver full power or it takes a lot longer to charge them up. I've seen several of these that "worked" but instead of being able to power through an entire shift like they are supposed to, they would die after 3 or 4 hours. With this being a new and unique setup, there would be no way to know if the battery was not delivering, or how long it should last. Also, with some of those big batteries, you need to consider how you are going to recharge them. Some of these things can take 100+ amps of charging current, and that will take a very large and robust charger drawing a lot of current. If you intend for a huge fork-truck type battery to recharge in 5 or 6 hours, your charger is going to need to be an industrial grade unit. Most of those run off of 480 volts, however.
Glenn Brooks
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Re: Electric drive motor specs

Post by Glenn Brooks »

Ok, picked up a new 6hp/4.5Kw 24v motor today at Bill’s used motors shop. Main advantage of this size motor is it easily runs on 4 , 6 volt golf kart batteries- (760amp capacity) and is a reversible motor. So can run in forward or reverse with a controller. This is a perfect size to mount cross ways above one axle. Should be a good experiment. If it works out OK, I’ll add a second one to the other truck, plus couple of more batteries.
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rkcarguy
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Re: Electric drive motor specs

Post by rkcarguy »

Very nice, what's the RPM on that?
Glenn Brooks
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Re: Electric drive motor specs

Post by Glenn Brooks »

2400 rpm on the plate...
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Steggy
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Re: Electric drive motor specs

Post by Steggy »

Glenn Brooks wrote: Wed Oct 28, 2020 11:22 pm 2400 rpm on the plate...
Shaft looks a little strange. Can it be turned to a standard (i.e., non-metric) diameter and a keyseat milled into it?
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
rkcarguy
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Re: Electric drive motor specs

Post by rkcarguy »

Glenn Brooks wrote: Wed Oct 28, 2020 11:22 pm 2400 rpm on the plate...
280 rpm at the axle with a 7" tire size is about 5.9mph. You're going to need about a 10:1 reduction between your motor and drive axles.
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Re: Electric drive motor specs

Post by Glenn Brooks »

Hiya BDD, Shaft is an odd length as it had a brake drum mounted on the end. It has an existing key way. Iam planning on just cutting the excess length off with a cutting disk, once I build a mounting plate, and finalize placement. BTW, just reread your EMD F7 build thread. Really nice work! How did your airsprings work out?

Ryan, Iam planning on a top speed of 10-12 mph, with an rpm at the axle of around 400-500. So looking for a sprocket reduction of 6:1 or thereabouts. I have room for a jackshaft and second set of sprockets for gear reduction if needed. Also an existing original tranny that came out of the body. Although these options are certainly not ideal. Shooting for KISS on this one...

Now at the moment, the exiting trucks are 12” ga. If the build proves acceptable, and I decide to go to a full rebuild, my thought is to add a second drive motor, 9” wheels, and build new heavy duty 15” ga trucks. I would fab up either splined wheels or key wheels with dual gauge capability, 12” and 15” ga settings, using 1 1/2” sleeves on each side of the axle. With 12” ga, drop the axles, put the sleeve on the inside of the wheel and presto- 15” gauge! Hopefully.

This loco would be a MOW machine and passenger hauler if we are successful in locating a site for a PNW live steam 15” ga club operation- hence designing it for possible future use.

Glenn
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Steggy
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Re: Electric drive motor specs

Post by Steggy »

Glenn Brooks wrote: Thu Oct 29, 2020 1:07 pmBTW, just reread your EMD F7 build thread. Really nice work!
Thanks!
How did your airsprings work out?
Are you referring to the gas springs that assist in opening the body? They work fine. A little tug on the body after releasing the latches and it opens just like the hood on your car.
Ryan, Iam planning on a top speed of 10-12 mph, with an rpm at the axle of around 400-500. So looking for a sprocket reduction of 6:1 or thereabouts. I have room for a jackshaft and second set of sprockets for gear reduction if needed. Also an existing original tranny that came out of the body. Although these options are certainly not ideal. Shooting for KISS on this one...
It's probably not practical to do 6:1 in a single stage. If you did, the axle sprocket would likely be as large in diameter as the wheel.
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
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