Is there a market for US TT?

Re: Is there a market for US TT?

Postby Bernd » Tue Feb 12, 2019 7:28 pm

Belt tension PDF file.
In case anybody is interested. he also has an xls spread sheet to calculated belt tension.




A few examples of belt and gear drive combined.

Friction drive:

Here's my prove of models using belts and pulleys. Seem to work just fine for me.

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Re: Is there a market for US TT?

Postby krokodil » Wed Feb 13, 2019 1:39 am

Hi Bernd

I do not want to create a long discussion in this topic, as it has not a direct relation to the TT scale - more to the general construction of model trains. In my opinion Nigel's constructions and theories are very much out of date. I am not saying that those models are not working, i just say that we are in 2019 and his constructions are from late 50-ies.
If you look at the model of with a belt drive. That is a huge waste of space for nothing. Today I would put a huge flywheel on the motor - there is a space for at least 14x7 mm flywheel - a huge improvement for the running quality of such small model! In worst case you can leave there the belt - but a gear transmission would bring another improvement especially in this case where you can easily adjust the motor position to the worm axle, that means practically you can adjust it to almost any gear size! (With the same efforts of the mechanical design)

Friction drive.
He is using micromotors, which are anyway limited in power. The friction drive eats up a significiant amount of energy - before the model starts to move.
His theory of the dropper resistor is unfortunately the worst, what you can do in model construction. The reason is very simple. The motor power requirement is not constant so the losses on the drop resistor will vary also in very bad way.
Just an example: on the 150 Ohm according his description there should be a drop of 6 V, ie 6V on the resistor and 6V on the motor. When the model starts to climb up to the hill, the current in the motor will increase what means, the voltage drop on the resistor will also increase (U=RxI), ie the voltage on the resistor will be let us say 8V and only 4V on the motor. This means the model will slow down and finally it will stop.
The same happens also when you couple some cars to the locomotive with such drive and resistor.
These are basic facts from physics.
Greetings from Austria
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