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Bernd
Fireman



Posted - 12/21/2019 :  10:10:24 AM  Show Profile  Visit Bernd's Homepage  Reply with Quote
While surfing another forum I came across a discussion of early motive power from the 19th century. The discussion revolved around why no manufacture's are producing 4-4-0's of that era. Also discussed was the fact how fast the models run as compared to the real thing. Mention was made of N scale models and how the motor is in the engine, not the tender, eliminating the need of a drive shaft. The question was asked why a manufacturer couldn't design a motor small enough to fit in the boiler of these engines.

Here's a picture of two engines I have. Both have motors in the tender.



As the thread went on it did not stay on track, one individual did mentioned getting motors from "The Motorman", unfortunately he passed on and that was the end of being able to obtain small motors from him. He mentioned that as the motors get small they don't seem to have lower RPM's. This true of many small can type motors. I mentioned that gearing could be used to reduce the output RPM to the drive wheels. As of yet no talk has ensued of that idea.

Of course this gave me the idea of doing some research on what's available in small motors with gearing. So, I have a question. To help me find an answer I need to know what the top speed, miles per hour, these 4-4-0's attained pulling a string of cars, both passengers and freight. Then using that figure I can go backwards and determine RPM of the motor and the gearing output needed to make the model run at prototypical speeds at 12 volts.

This will be a side project that get's worked on as time permits.

Bernd

WWG1WGA

Country: USA | Posts: 3629

jbvb
Fireman

Premium Member


Posted - 12/21/2019 :  10:24:02 AM  Show Profile  Visit jbvb's Homepage  Reply with Quote
The generalization I've heard is that the practical speed limit is about 370 RPM at the drivers.


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deemery
Fireman

Premium Member


Posted - 12/21/2019 :  10:29:01 AM  Show Profile  Reply with Quote
As I recall, max speed is a function of driver size. For those era locos, though, I think you'd be safe to assume maybe 50MPH.

dave


Modeling 1890s (because the voices in my head told me to)

Country: USA | Posts: 8511 Go to Top of Page

BurleyJim
Fireman

Premium Member


Posted - 12/21/2019 :  11:01:25 AM  Show Profile  Reply with Quote
Small motors? A good place to check out, might be the micromotors that are in the small drones or helicopters. I just tossed a small (< 20$) helicopter in the trash last week, Should have stripped out the cylindrical shaped motors and tested.

Jim


Take the red pill

Country: USA | Posts: 5583 Go to Top of Page

rca2
Engine Wiper

Posted - 12/21/2019 :  11:28:46 AM  Show Profile  Reply with Quote
I would consider the design intent of the model. Few people model maintrack areas where trains hit top speeds. Look at the distance between stations in scale miles. Most often trains are sitting on a siding or moving under restrictions. For the mountain RR prototype branch I model in 1920, the average scheduled freight speed was about 13 mph and about twice that for passenger trains. There were 30 stations in 103 miles. Not to mention curves, tunnels, bridges, and grade crossings. Most of the time was spent accelerating after a stop or preparing to stop.

JBVB and Dave make a good point about RPM. Passenger power generally had larger drivers for higher speeds pulling lower tonnage.


Modeling Arizona Eastern Railroad, Hayden Junction (1920), in On30

Country: USA | Posts: 463 Go to Top of Page

brian budeit
New Hire

Posted - 12/21/2019 :  12:16:46 PM  Show Profile  Reply with Quote
Keep in mind the AHM old time engines were first made in the 1960's, and used a standard Rivarrossi three pole motor, same motor no matter if it was the JW Bowker or the U P Big Boy. In fact, those "old time" engines were 1/76 scale to give more room for the motor and weight so the engines could pull a short train.
Wayne Weiss, the Loco Doc, sells very fine motors. My favorite are the Faulhaber 13x19 24 volt motors that top out around 8000 rpm.Small enough for most hon3 engines, and slow and powerful enough that there is no need to change gearing. Be advised, they are not cheap, but are a solution to overly fast running models.
I wouldn't doubt that the chinese have bootlegged the Faulhaber motors, some looking on the internet might turn up some cheap alternatives. Most recent examples were small motors taken from old cameras, used to extend the lens. You might have a usable motor sitting in your junk drawer in an obsolete electronic device.
brian b



Country: USA | Posts: 34 Go to Top of Page

Early1905
New Hire

Posted - 12/21/2019 :  3:58:45 PM  Show Profile  Visit Early1905's Homepage  Reply with Quote
There are new 4 magnet, 6 pole motors that are now available. Sizes of 10mm sq, 15mm sq and 18mm sq.
These have great torque and a lower speed then other motors their size. Check ebay, the price is right. These are the go to motors on the re-motoring list on groups.io

Howard Garner



Country: USA | Posts: 20 Go to Top of Page

Bernd
Fireman



Posted - 12/21/2019 :  4:37:43 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by jbvb

The generalization I've heard is that the practical speed limit is about 370 RPM at the drivers.



That's a good bit of info to remember. I still need to know what the top speed of one of these engines was to come up with the rpm of the drivers.

Bernd


WWG1WGA

Country: USA | Posts: 3629 Go to Top of Page

Bernd
Fireman



Posted - 12/21/2019 :  4:40:35 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by deemery

As I recall, max speed is a function of driver size. For those era locos, though, I think you'd be safe to assume maybe 50MPH.

dave



Ah Dave, thanks, that's what I was looking for. I'd figured 30 to 50 mph in those days. Just wanted to make sure.

Bernd


WWG1WGA

Country: USA | Posts: 3629 Go to Top of Page

Bernd
Fireman



Posted - 12/21/2019 :  4:46:21 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by BurleyJim

Small motors? A good place to check out, might be the micromotors that are in the small drones or helicopters. I just tossed a small (< 20$) helicopter in the trash last week, Should have stripped out the cylindrical shaped motors and tested.

Jim



Jim,

I take it was something like this?



Those motors work on 3.7 volts from a lithium battery. They are coreless motors and spin at a very high rate of rpm's. Might work for a carnival ride.

Bernd


WWG1WGA

Country: USA | Posts: 3629 Go to Top of Page

Bernd
Fireman



Posted - 12/21/2019 :  4:50:43 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by rca2

I would consider the design intent of the model. Few people model maintrack areas where trains hit top speeds. Look at the distance between stations in scale miles. Most often trains are sitting on a siding or moving under restrictions. For the mountain RR prototype branch I model in 1920, the average scheduled freight speed was about 13 mph and about twice that for passenger trains. There were 30 stations in 103 miles. Not to mention curves, tunnels, bridges, and grade crossings. Most of the time was spent accelerating after a stop or preparing to stop.

JBVB and Dave make a good point about RPM. Passenger power generally had larger drivers for higher speeds pulling lower tonnage.



Bob,

Thanks for the input. I'm basically looking for the proper gearing so the engine runs at top speed when the throttle is at max setting of 12 volts.

Bernd


WWG1WGA

Country: USA | Posts: 3629 Go to Top of Page

Bernd
Fireman



Posted - 12/21/2019 :  4:54:10 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by brian budeit

Keep in mind the AHM old time engines were first made in the 1960's, and used a standard Rivarrossi three pole motor, same motor no matter if it was the JW Bowker or the U P Big Boy. In fact, those "old time" engines were 1/76 scale to give more room for the motor and weight so the engines could pull a short train.
Wayne Weiss, the Loco Doc, sells very fine motors. My favorite are the Faulhaber 13x19 24 volt motors that top out around 8000 rpm.Small enough for most hon3 engines, and slow and powerful enough that there is no need to change gearing. Be advised, they are not cheap, but are a solution to overly fast running models.
I wouldn't doubt that the chinese have bootlegged the Faulhaber motors, some looking on the internet might turn up some cheap alternatives. Most recent examples were small motors taken from old cameras, used to extend the lens. You might have a usable motor sitting in your junk drawer in an obsolete electronic device.
brian b



Brian,

Thanks for the input. I'm looking at the small motors on Ebay. Many have a gearbox attached already. I have several already that I've test. Also my idea of a gearbox is one attached to the motor, not one that is mounted between the frames in a locomotive.

Bernd


WWG1WGA

Country: USA | Posts: 3629 Go to Top of Page

Bernd
Fireman



Posted - 12/21/2019 :  4:56:27 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by Early1905

There are new 4 magnet, 6 pole motors that are now available. Sizes of 10mm sq, 15mm sq and 18mm sq.
These have great torque and a lower speed then other motors their size. Check ebay, the price is right. These are the go to motors on the re-motoring list on groups.io

Howard Garner




Thanks for the input Howard. I'm aware of the motors available on ebay.

Bernd


WWG1WGA

Country: USA | Posts: 3629 Go to Top of Page

Carrie Creek
Fireman

Premium Member


Posted - 12/21/2019 :  6:30:40 PM  Show Profile  Reply with Quote
Available speed is a function of the mass and speed of the piston. The speed of the piston is controlled by the stroke length. Shorter stroke less speed.( Which is why a short stroke internal engine can rev higher than a longer stroke.) So, the max rpm speed is dependent on the mass and stroke of the pistons. For more vehicle speed it requires a bigger dia. driver for the same stroke.
For the speed of a particular driver diameter find the circumference in feet, divide a mile by that distance for the number of revs per mile then multiply by rpms needed for your wanted mph.
I don’t think a 4-4-0 could handle the physics of more than 500rpms.


Phil Z
POR (press on regardless)

Country: USA | Posts: 1572 Go to Top of Page

Bernd
Fireman



Posted - 12/21/2019 :  7:30:10 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
Phil,

I'm quite award of steam engine dynamics. Live steam was one of my hobbies.

I'm sure the engines were no speed demos by todays standards. I think I have enough info to do what I want to try. Thanks for the additional info.

Bernd


WWG1WGA

Country: USA | Posts: 3629 Go to Top of Page

Carrie Creek
Fireman

Premium Member


Posted - 12/21/2019 :  8:53:25 PM  Show Profile  Reply with Quote
Berne, Your original question was how fast the 4-4-0 went at top speed which I thought was not a tough question to answer knowing your mechanical expertise. So, I pulled out my book on Mason’s locomotives to see the driver sizes of his. They were running 60”-66” dia. So did some quick math and came up with for the 60”
15.7’ cir. = 336.3 revs/mile/ minute= 60mph
The 66” would be faster at the same revs.

Does this help?


Phil Z
POR (press on regardless)

Country: USA | Posts: 1572 Go to Top of Page
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