GE 23 ton boxcab in 7.5" gauge / 1.5" scale

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Pontiacguy1
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Pontiacguy1 » Wed Oct 14, 2015 6:46 pm

Make sure your bearings are pressed or loctited to the axle or you're going to have problems with th ball bearings. There should be some amount of movement but it should be between the bearing OD and the journal box.

Jawn
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Jawn » Wed Oct 14, 2015 7:01 pm

Chooch, I had planned to have about a 3:1 reduction from the motor to the jack shaft, then anywhere from 1:1 to 3:1 from the jack shaft to wheels depending on the RPM of whatever motor I choose. So you're on the same train of thought as me, in that regard.

Pontiacguy1 wrote:Make sure your bearings are pressed or loctited to the axle or you're going to have problems with th ball bearings. There should be some amount of movement but it should be between the bearing OD and the journal box.
Will do!

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steamin10
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by steamin10 » Wed Oct 14, 2015 7:20 pm

I disagree: the journal boxes may fit tight to the bearings, and axle stub. The rock roll and side slide are in the journal box clearance for the 'Wiggle' when you bounce along the rails.

The T shaped drive chain configuration is OK, if you take into account that you have 3 tooth counts to get your drive ratio. The largest drop should be the first one, and fit a small gear to a very large gear, to capture the working torque of the motor. If done in the second phase, it increases the draw of the axles together, and will restrict the movement in the vertical slides. So the smaller adjustment to ratio, should occur there.

I like about a ten to one reduction, that allows the motors to spin in the upper reaches of their range, as they will heat less, and live happy spinning free. If you load them, you are on the road to destruction with heat.

I like a 10-1, or 12-1 drive if it will fit.

Gearbox- 12 tooth pinion, 120 tooth bull. This creates some wear when the motor coasts, being driven by the bull gear. But it works fine. A double reduction case makes 12-1 easy on the gears, but much more monkey to build the case to install it.
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Jawn
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Jawn » Wed Oct 14, 2015 7:54 pm

How about chain sizes? I see a lot of the motors in this size range come with a small #25 sprocket. Any reason not to stick with that through the whole drivetrain?

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BigDumbDinosaur
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by BigDumbDinosaur » Wed Oct 14, 2015 11:12 pm

Jawn wrote:I just received some wheels (four destined for this locomotive, four probably for a bobber caboose). I have some 4130 steel rod I plan to use for axles (what size should it be? I have an assortment), and 26mm OD x 9mm ID x 8mm wide ball bearings.
I'd go with one inch diameter for the axles, but would not use 4130. A better choice, in my opinion, would be C1144 TGP, which is plenty strong but much less difficult to machine. That is the material I used to make the axles for my control car.

The 9mm × 26mm bearings are roughly scale, but will result in a small diameter axle end (~.354") that could eventually fatigue and break off. Just an opinion, but I wouldn't use any bearing whose bore is less than 13mm.
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BigDumbDinosaur
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by BigDumbDinosaur » Wed Oct 14, 2015 11:13 pm

Jawn wrote:How about chain sizes? I see a lot of the motors in this size range come with a small #25 sprocket. Any reason not to stick with that through the whole drivetrain?
Number 25 is essentially bicycle chain, and is meant for low speed, moderate torque applications. I'd use the next size up, number 35. Be sure to use sprockets with hardened teeth.
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chooch
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by chooch » Thu Oct 15, 2015 10:24 pm

Nothing wrong with # 25 chain from motor to first gear. Then change to # 25 (or better) for the rest of the drive system. I and some friends have just such chain systems and run with no problems. For such a Small boxcab, and larger than 1/2 " axles of plain old steel rod I opinion is ridiculous.
I have at least 24 cars of various size, type and weight, a speeder,six locos of 4-6-and 8 wheels. All run just fine. You`re building a Small loco, not a battleship.
chooch

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Fender
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Fender » Fri Oct 16, 2015 5:06 am

My Davenport loco uses #35 chain from the motor to the jackshaft. Wish I had used #25 instead. The smaller chain is better suited to the higher speeds. To reduce the noise I switched to a delrin plastic sprocket on the motor shaft.
When I first built this, there was about a 1:6 reduction. This resulted in a "white knuckles" trip around the track! I now have about 1:12.
Dan Watson

chooch
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by chooch » Fri Oct 16, 2015 6:23 am

I don`t follow how different size chain or Delrin sprocket would change the speed. I would think it would be a Change in sprocket Sizes that make gearing ratio different.
Yes, I have the same thing--to fast really but a lot of work to change sprockets and be carefulI of messing up the side rod connections. just run it slower.
chooch
Fender wrote:My Davenport loco uses #35 chain from the motor to the jackshaft. Wish I had used #25 instead. The smaller chain is better suited to the higher speeds. To reduce the noise I switched to a delrin plastic sprocket on the motor shaft.
When I first built this, there was about a 1:6 reduction. This resulted in a "white knuckles" trip around the track! I now have about 1:12.

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cbrew
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by cbrew » Mon Oct 19, 2015 11:54 am

# 25 chain as proven to be big enough when running these small electric motors,
just not enough power to break it, the kiddos have tried :roll:

this is the drive train i can up with on the units i have built in the past.
everything is below the deck leaving room above for the batteries, sound and controller


1455190_10152063223753185_1444019330_n.jpg
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fresnojay
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by fresnojay » Wed Oct 21, 2015 12:01 am

Jawn if going for a 23T reasonably close to scale you can mount the motor above the deck plate yes, but there will be plenty of room below it for the motor. From experience you will want the room in the cab that the motor in your design is occupying.

As for the drive chain #25 is more than adequate in my experience. I have pulled close to 2000# using a drive system of #25 on a 500W scooter motor on 24V. I have blown fuses but never a chain.

In my 23T I run 2 group 27 marine deep cycles set exactly as you have them in your design save for my motor is below the deck in between the frames like Chris' picture shows.

Hope this helps,
Jason

Jawn
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Jawn » Thu Oct 22, 2015 4:11 pm

fresnojay - How on earth did I miss your build thread? Great looking loco!

Anyhoo, I think what I have in mind for chassis construction is very similar to yours... but group 27 batteries? I am guessing you scaled it up from "scale size" just a hair? I had initially planned building to the drawing in my first post, at 1.5" scale. What are the overall dimensions of your loco?

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