Motor Possibility

Motor Possibility

Postby Bernd » Sat Feb 23, 2019 6:37 pm

The iMaterials U30b had got me thinking about the GP38-2 resin shell I have and the drive I was developing for it. Back around March of 2015 I had started to look for a motor/motors that would fit in the shell. I purchased several chassis mechanisms for their motors and drive shafts on E-bay.

The first idea was to use a Daw-Tek product from China. It was found on E-bay.

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Next were two Kato mechanisms for a twin motor drive.

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After I had experimented with belt drives from Nigel Lawton I came up with the idea of using a full length shaft and possibly a driven pulley on that shaft. Never got to far with that idea.

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This is one of the motors Brian had sent me for testing. I thought it would be a good candidate for he belt drive.

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Today I was surfing E-bay and came across this vendor in the Netherlands. https://tramfabriek.nl/

They have three styles of "coreless" motors. Something I'd like to try out. I have two big, for HO application, coreless motors that are very quite and powerful. I've been reading where modelers that upgrade steam engines, in HO, are using coreless motors. I went looking on E-bay and came across the vendor mentioned above.

Here's a direct link to the motor page.https://tramfabriek.nl/motors.html I'm thinking either the 0816D or two 0816S. I think using two motors would give the model lots of power for pulling a train. Comments, observations?

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Re: Motor Possibility

Postby TinGoat » Sat Feb 23, 2019 8:34 pm

I don't know if it's true but I had heard that you can't use DCC on coreless motors.

That may have been true a few years ago but maybe DCC has improved their sin wave dc since then.

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Re: Motor Possibility

Postby AstroGoat760 » Sun Feb 24, 2019 1:04 am

Those possibilities are definitely tempting to find more out about!
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Re: Motor Possibility

Postby krokodil » Sun Feb 24, 2019 5:23 am

TinGoat wrote:I don't know if it's true but I had heard that you can't use DCC on coreless motors.

That may have been true a few years ago but maybe DCC has improved their sin wave dc since then.

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There should not be any conflict anymore. The coreless ( Faulhaber, Maxxon, Sagami etc) motors are the high end solutions in the model railroad applications and all recently produced DCC decoders have the option to drive them ( high frequency PWM. >10 kHz).
On the other hand the coreless motors not always deliver the expected benefits ( in comparison to their prices) so the majority of models still use the traditional "cored" motors, which went through also over many upgrades for model railriad applications. The modern motors have at least 5 poles, skewed armature, sintered bearings and are less sensitive to the power specs as the coreless motors do.
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Re: Motor Possibility

Postby krokodil » Sun Feb 24, 2019 6:07 am

Bernd

They have three styles of "coreless" motors. Something I'd like to try out. I have two big, for HO application, coreless motors that are very quite and powerful.


They have 3 styles, but take care they are all very small, up to 8 mm in diameter. That is perfect for very small models ( look also their products - all engines are small, 2-3 axles) and the smaller diameter in this case means also higher speed, ie those motors have 13000 or more RPM. The average wheels of a TT diesel locomotive requires a max of about 6-800 rpm. ( depends on the diameter, bigger wheel smaller RPM).
After simple calculation for a realistic speed of a mainline locomotive: the reduction ratio is about 20, for a switcher: 30 or higher.
This is the next challenge how to reach this reduction.
On the TT wheel axles you can have cogwheels with max of about 15 teeth (or cca 7 mm in diameter). A simple worm gear will reduce the motor rpm only by 15, ie it is the half of the required reduction ratio.
More complex reduction creates a problem in gear housing and probably you need finer gears ( in decimal world towards Modul 0,3 or even smaller. This increases the requirements for production accuracy - look the watchmakers or precision mechanizm).

Look at the http://www.davall.co.uk/media/1877/CONVERSION%20DP%20to%20CP%20to%20MOD.pdf . We are talking about gears with D.P. 64-80, or Modules 0,4-0,3
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Re: Motor Possibility

Postby krokodil » Sun Feb 24, 2019 6:13 am

Bernd

The last two pictures are showing an interesting construction. If you find a flat motor what you can embed into the frame bellow the longitudional axle would be nice. From the motor up to the axle you can make a reduction of 1:2-1:3, and the rest can be done on the worm gears. Probably you can also lift the axle closer to the hood roof to gain more place for the motor bellow.
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Re: Motor Possibility

Postby Bernd » Sun Feb 24, 2019 11:36 am

The specifications for the 0816S are: Min RPM: 400 ; No load speed: 13,000 ; No load current: 6 mA ; Rated speed: 11,500 ; Rated current: 30 mA ; Rated torque: 3g.cm ; Stall torque: 14.5g.cm ; Stall current: 0.21 A

Now using the "Select-A-Speed" chart from North West Short Line web site: http://nebula.wsimg.com/02d6e40c2d04190212ed400d3ccb2472?AccessKeyId=08BEE66B97B387F20C0D&disposition=0&alloworigin=1 we can calculate a belt ratio to slow the RPM of the wheels down to the proper speed. With a 40" wheel diameter and a top speed of 70 mph (112 kph) the needed gear reduction is approximately 17.5 to 1. I'm using the 11,500rpm of the motor because it will be driving the shaft that is connected to the towers and a wheel diameter of 40".

I'm going to try out the drive belt on the second to last picture that you find interesting. Also is there a consensus that those gear towers are 16:1?

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Re: Motor Possibility

Postby ConducTTor » Sun Feb 24, 2019 12:44 pm

Hey Bernd (and anyone else who has experience), what is your experience with twin motor drives? I've thought about this solution but have been concerned about the two motors not being exactly in sync (where one boggie is dragging the other and the other is holding the first one back).


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Re: Motor Possibility

Postby ConducTTor » Sun Feb 24, 2019 12:51 pm

Also, does a dual motor setup require two decoders?


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Re: Motor Possibility

Postby krokodil » Sun Feb 24, 2019 1:00 pm

Bernd wrote:The specifications for the 0816S are: Min RPM: 400 ; No load speed: 13,000 ; No load current: 6 mA ; Rated speed: 11,500 ; Rated current: 30 mA ; Rated torque: 3g.cm ; Stall torque: 14.5g.cm ; Stall current: 0.21 A

Now using the "Select-A-Speed" chart from North West Short Line web site: http://nebula.wsimg.com/02d6e40c2d04190212ed400d3ccb2472?AccessKeyId=08BEE66B97B387F20C0D&disposition=0&alloworigin=1 we can calculate a belt ratio to slow the RPM of the wheels down to the proper speed. With a 40" wheel diameter and a top speed of 70 mph (112 kph) the needed gear reduction is approximately 17.5 to 1. I'm using the 11,500rpm of the motor because it will be driving the shaft that is connected to the towers and a wheel diameter of 40".

I'm going to try out the drive belt on the second to last picture that you find interesting. Also is there a consensus that those gear towers are 16:1?

Bernd


Bernd

The 30 mA maximum power will be insufficient for such construction 12Vx0,03 A = 0,36W. You need for such locomotive ( no load) over 2W, with load ( long train) 4-5 W. Even the stall current is very low 12Vx0,21A is just about above of normal power what you need to move the loco.

I had a same problem with the last MDC Shay, there was also a very weak coreless motor ( instead of the former DC-11 or similar). The new motor was not able to turn the gears of the Shay. ( but it was coreless :-( ).
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