1/24 scale Japanese C62 by katsumiadachi

[Brian McKenzie]

Brass bashers in the larger scales might be intrigued with this loco model's deliberate slipping motion of driving wheels.

The loco appears to be propelled ordinarily using a tender drive, while the lightly loaded driving wheels are driven separately for the slipping effect.

The tender drive incorporates a massive lump of "continuous cast bronze" (the markings from the bronze's extrusion process can be seen at 2:10 - it's not a lump of wood ! )

-Brian McK

 

[Matt.S.]

All very clever but I'm not sure why you'd want to mimic slipping?

 

[Dave Holt]

I can't see any evidence of a motor in the tender. I think the loco is powered to the driving wheels in the usual way. The geared rotating mass in the tender acts as an initially very high resistance load, causing the loco wheels to slip in a prototypical manner. Then, as the rotating mass gradually increases in rotational speed, it offers less and less resistance and the loco ceases to slip. The tender mass then acts as a flywheel.
Dave.

 

[Andrew Taylor]

All very clever but I'm not sure why you'd want to mimic slipping?

The Bullied pacific springs to mind.

 

[J_F_S]

All very clever but I'm not sure why you'd want to mimic slipping?

I have always wanted to do this with a Bulleid pacific - not least because in the absence of slipping, the thing would be hopelessly unrealistic!

 

[simond]

I guess it would be possible to arrange the reaction force from the motor to apply to the trailing truck. This would unload the driving axles, and promote slipping when the torque was sufficient. Springs may be required…

The problem is that the slipping of a real loco is unlikely to scale well, if nothing else, because a geared-down electric motor does not provide four or six (or maybe eight) torque pulses per revolution, and the effects of friction and particularly stiction are very load dependent.

I suspect that it would require some rather sophisticated software in the motor controller.

 

[Mike W]

The geared rotating mass in the tender acts as an initially very high resistance load

That reminds me of a friend who built two GWR Toads in 7mm either just before or after the War and they were filled by a massive flywheel, gear driven from the wheel flanges at one end. They were not so much to induce slipping as to create realistic coupling slack when power was applied or reduced, also for fly shunting. I believe W.S.Norris had one of them and I lost track of the other about 3 years ago. It sounds like you're suggesting a similar arrangement inside the tender. , albeit for a different purpose.

 

[michael080]

That reminds me of a friend who built two GWR Toads in 7mm either just before or after the War and they were filled by a massive flywheel, gear driven from the wheel flanges at one end. They were not so much to induce slipping as to create realistic coupling slack when power was applied or reduced, also for fly shunting. I believe W.S.Norris had one of them and I lost track of the other about 3 years ago. It sounds like you're suggesting a similar arrangement inside the tender. , albeit for a different purpose.

many years ago there was a model of a German steam engine, I believe from Rivarossi, that had a cetrifugal clutch and a large flywheel. The problem was that it started rolling as soon as it was standing on the slightest gradient.

 

[Osgood]

Does anyone remember DYNADRIVE - an interesting centrifugal clutch based system, appeared in the model railway press maybe late 70s?

 

[timbowales]

Yes, I remember it being advertised. Wasn't there an article in MRJ about it?

 

[Osgood]

Yes, I remember it being advertised. Wasn't there an article in MRJ about it?

Oh yes, well done!

 

[Osgood]

That reminds me of a friend who built two GWR Toads in 7mm either just before or after the War and they were filled by a massive flywheel, gear driven from the wheel flanges at one end. They were not so much to induce slipping as to create realistic coupling slack when power was applied or reduced, also for fly shunting. I believe W.S.Norris had one of them and I lost track of the other about 3 years ago. It sounds like you're suggesting a similar arrangement inside the tender. , albeit for a different purpose.

What an interesting idea - something I would like to try.

 

[timbowales]

Oh yes, well done!

View attachment 237510

Good grief, that was 36 years ago!

 

[J_F_S]

I suspect that it would require some rather sophisticated software in the motor controller.

Rather to use two motors - my idea was to create the forward movement via a tender drive with a second and separate motor driving the (lightly sprung) drivers with separate DCC addresses to allow 'realistic' independent combinations of slip/grip. All utter, complete and impractical fantasy of course - not least because my layout is DC!

But I think our Japanese friend has a wonderful soultion and it works well with prefect slip/grip stiction - albeit perhaps not for 4mm (there is a challenge for someone: where are you Dave Holt?). There might be an interesting gyroscopic effect at a scale 70mph ... and it coulg probably do with some positive control of braking ...

I am still pondering the flywheel fitted Toads - what a good idea and what a creative hobby this is!