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Ruston's Industrial locomotive and wagon workshop thread.


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1 hour ago, Ruston said:

... compared with the results I've had with the N20 gearmotors in previous engines, this one is woeful.

 

That is a great shame - I had high hopes for this unit and have acquired several for trials.

 

I wonder if it might be possible to replace the worm and pinion with bevel gears?

 

Any thoughts?

 

John Isherwood.

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22 minutes ago, cctransuk said:

 

That is a great shame - I had high hopes for this unit and have acquired several for trials.

 

I wonder if it might be possible to replace the worm and pinion with bevel gears?

 

Any thoughts?

 

John Isherwood.

Not in the unit itself. The way I have made the chassis means it's relatively simple to swap out the entire power unit, so when HL gearboxes become available again, it will probably be fitted with a Roadrunner.

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May I ask which N20 set you are using? From the pics they appear to be "D" version. I have here a D and C version side by side, 381 shaft RPM compared to 136 shaft RPM and just now did a quick back to back test using a finger on the final drive, ( not very scientific, I know ) and the C felt to have much more torque. As I see it the units are identical apart from an extra reduction in the gearbox on the third shaft with the motor spinning much more freely, by nearly X 3 per output shaft RPM?

Edited by Carnforth
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5 hours ago, Carnforth said:

May I ask which N20 set you are using? From the pics they appear to be "D" version. I have here a D and C version side by side, 381 shaft RPM compared to 136 shaft RPM and just now did a quick back to back test using a finger on the final drive, ( not very scientific, I know ) and the C felt to have much more torque. As I see it the units are identical apart from an extra reduction in the gearbox on the third shaft with the motor spinning much more freely, by nearly X 3 per output shaft RPM?

Who's designations are the C and D? It's supposedly 381rpm but what that means I have no idea because the rpm is surely dependent on the voltage and load. The other type, that require the drive to be turned via bevel gears, were bought as 300 rpm.

 

I am sure the lack of torque is all down to the worm being between the motor and the gearbox proper. I first started using gearmotors in 2018 after seeing, on Facebook, what Geoff Helliwell had done with them in his 3mm scale locos. He said that he built a motor bogie that he can press down on with his hand "until my knuckles were white" and the wheels would keep turning. None of these, or the 6 that I have used until now, have the worm on the end of the motor. Geoff Helliwell also wrote an article on the subject in the April 2018 Railway Modeller.

 

39 minutes ago, Barclay said:

Is there room to fit another one on the front axle? That would do the trick !

Do you mean is there room to fit two on one axle?

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1 minute ago, Ruston said:

Who's designations are the C and D? It's supposedly 381rpm but what that means I have no idea because the rpm is surely dependent on the voltage and load. The other type, that require the drive to be turned via bevel gears, were bought as 300 rpm.

 

I am sure the lack of torque is all down to the worm being between the motor and the gearbox proper. I first started using gearmotors in 2018 after seeing, on Facebook, what Geoff Helliwell had done with them in his 3mm scale locos. He said that he built a motor bogie that he can press down on with his hand "until my knuckles were white" and the wheels would keep turning. None of these, or the 6 that I have used until now, have the worm on the end of the motor. Geoff Helliwell also wrote an article on the subject in the April 2018 Railway Modeller.

 

Do you mean is there room to fit two on one axle?

Sorry no I mean the other axle.

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3 minutes ago, Barclay said:

Sorry no I mean the other axle.

Not in this loco, not now I've stuck lead sheet in the body. I'm not sure that it would work in any case. It would only need one unit to be a bit freer running than the other, for a given voltage, and they'd start to fight each other. I don't think it would run smoothly at all and may get to a point where it all locks up. Using more than one motor and gearbox is an idea that I've had for some time, but in something without rods, such as a Thomas Hill Steelman 6wDH.

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1 minute ago, Ruston said:

Not in this loco, not now I've stuck lead sheet in the body. I'm not sure that it would work in any case. It would only need one unit to be a bit freer running than the other, for a given voltage, and they'd start to fight each other. I don't think it would run smoothly at all and may get to a point where it all locks up. Using more than one motor and gearbox is an idea that I've had for some time, but in something without rods, such as a Thomas Hill Steelman 6wDH.

Fair point it could produce some interesting effects !

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Who's designations are the C and D? It's supposedly 381rpm but what that means I have no idea because the rpm is surely dependent on the voltage and load. The other type, that require the drive to be turned via bevel gears, were bought as 300 rpm.

 

My take on this is that on full volts, this will be the output shaft speed. I did note that the third shaft within the gearbox has different gearing and creates a bigger reduction in C rather than D. So for the same motor speed,  the output shaft speed should be around 1/3 with box C. Exact figures may be academic but I may have client's project to experiment with, at my risk, with alternatives available in the near future so I'll be sure to relay my findings.

 

Edited by Carnforth
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I've got two of these to evaluate, quick check with power on suggests there is enough power at the axle. In the light of what Dave has reported I'll try with a small loco first. The n20 and bevel gears has now moved up to fitting in a 7mm 05 weighted to about 650g - it can still easily spin its wheels.

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My experience generally with the N20s is the same as Dave's - that they are unstoppable when driving through bevel gears (also much more controllable when fed 60Hz when using radio control...). I once tried a hybrid drive with an N20 gearmotor and a worm and gear final drive to axle, and the performance was abysmal in comparison (5:1 gearmotor and 20:1 worm and gear). 

 

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5 hours ago, Giles said:

My experience generally with the N20s is the same as Dave's - that they are unstoppable when driving through bevel gears (also much more controllable when fed 60Hz when using radio control...). I once tried a hybrid drive with an N20 gearmotor and a worm and gear final drive to axle, and the performance was abysmal in comparison (5:1 gearmotor and 20:1 worm and gear). 

 

Since the whole of an N20 gear motor is to eliminate the losses of a worm and wheel at the expense of more efficient gears (spur or bevel), it is hardly surprising that using a worm and wheel makes the thing useless, as the original design was to make use of the advantages of not using a worm and wheel to permit a cheaper, less powerful motor.

This is akin to complaining that a 125cc single-seater motorbike can’t haul a heavy caravan at 60mph down the M1.

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13 minutes ago, Regularity said:

This is akin to complaining that a 125cc single-seater motorbike can’t haul a heavy caravan at 60mph down the M1.

I bet Top Gear would have a go!

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4 minutes ago, 5050 said:

I bet Top Gear would have a go!

The thought had crossed my mind - particularly if it leads to the destruction of another caravan!

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Regularity -  Indeed..... I had good reason to do it at the time, and also I believe in trying things out.

Of course I'm not complaining - but I am hopefully adding to the information out there, and trying to make the point how great the difference in performance is - or if you'd rather - the difference in efficiency of the worm drives that we commonly use (as opposed to the efficient highly engineered worms, whose efficiency can be very high) and bevel gears which are of their nature very efficient.

 

Of course Portescaps used bevel gears on the motor shaft to drive the first gearbox shaft.

 

Slightly off topic, I have also done a reasonable amount with micro planetary gearboxes, and found them excellent. They also provide the flexibility of reducing the number of stages to change the ratios if required, and changing the motor to suit the application.

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Interesting conversation about N20s. My only use for one so far has been a plain, without a gearbox, example which is a replacement motor for the Dapol/Model Rail Sentinel. It drives the supplied  four wheel drive gearbox via a worm and its fine.

 

I have attempted to use a 100rpm N20+gearbox via bevel drive but the project was let down by the issues I had surrounding reaming out the bevel gear of 3mm i/d to an i/d of 1/8". I couldn't get the i/d to be perpendicular to the gear teeth. This caused an end thrust to the axle which caused the model to waddle about in a most unbecoming way. I decided that in future I would use a 3mm axle but AGW only has a limited range of 3mm bore driving wheels.

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Sorry to hear that David - I use the Technobots Mod 0.5 black plastic bevel gears where I can (my narrow gauge locos need the smaller 0.3  brass ones on 2mm axles). If you want to repeat the experiment let me know and I'll drill you out one 1/8" and one 3mm.

 

Giles

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20 minutes ago, Giles said:

Sorry to hear that David - I use the Technobots Mod 0.5 black plastic bevel gears where I can (my narrow gauge locos need the smaller 0.3  brass ones on 2mm axles). If you want to repeat the experiment let me know and I'll drill you out one 1/8" and one 3mm.

 

Giles

Thanks for that, most appreciated.

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The Hudswell now has brakes, lettering, and a light weathering, so I'm calling this one finished, although I may add some more weathering.

HCfin-013.jpg.1f49b9838476b6b7a26cf695a505ab68.jpg

It is still running on plain DCC and requires sound to be fitted.

Edited by Ruston
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On 22/06/2021 at 17:23, Ruston said:

 ....compared with the results I've had with the N20 gearmotors in previous engines, this one is woeful.

 

I ordered a couple of different gear ratios of these worm gearbox motors, following your mention of them.

 

Whilst I have not yet installed them in locos, I have to say that I find that I am unable to stall them by gripping the output shafts, despite the D flats on them.

 

I am powering the motors with my home-built variable voltage controllers.

 

John Isherwood.

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40 minutes ago, cctransuk said:

 

I ordered a couple of different gear ratios of these worm gearbox motors, following your mention of them.

 

Whilst I have not yet installed them in locos, I have to say that I find that I am unable to stall them by gripping the output shafts, despite the D flats on them.

 

I am powering the motors with my home-built variable voltage controllers.

 

John Isherwood.

You had me doubting myself there, so I have just tried the other three that I have, all of which are 381rpm type. I can stall them by gripping a finger and a thumb on the ends of the output shaft. Gripping the shaft itself, between finger and thumb, it stalls fairly easily. Either you have a different ratio that gives more torque at the shaft, or you have a far weaker grip than I.

 

I also tried one of the other type as a comparison. The type, that folds back on itself (300 rpm) and would require bevel gears and I cannot stall that at all.

 

By the way, I put some Rocol anti scuff paste on the worm of the unit fitted in the Hudswell and the loco can now spin its wheels whilst I put something in front of it to stop it from moving. The motor is straining but at least it doesn't stall now.

Edited by Ruston
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STOP PRESS!

 

I have repeated the same test train as I ran before. 18 heavy wagons being moved from a stand on a tight curve. Now that it can spin its wheels it can pull this load with the wheels slipping slightly. On the first test it only had a light oil on the gears and worm. Decreasing the friction at the worm,by applying the anti scuff paste, has improved things enormously.

 

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2 hours ago, cctransuk said:

 

I ordered a couple of different gear ratios of these worm gearbox motors, following your mention of them.

 

Whilst I have not yet installed them in locos, I have to say that I find that I am unable to stall them by gripping the output shafts, despite the D flats on them.

 

I am powering the motors with my home-built variable voltage controllers.

 

John Isherwood.

That's what I've found too.

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