Two Motors (Midland Pullman or other multiple units)

[seahorse]

I have a Triang/Hornby Midland Pullman with three centre cars ( refitted with modern wheels). It runs better pulling than pushing. So I have bought another motor unit. They are not quite matched so it still runs better one way than the other, with the centre cars giving an uncomfortable ride for my "passengers". It's better, but I am looking to improve it further ( without the obvious solution of a Bachmann one!!)

 

I would like to have the front unit doing the work, with rear unit almost free-wheeling in either direction

 

Can I fit a resistor and diode to each motor? If so what resistor and what diode? Resistor in series with diode across the motor, or resistor in series with motor with diode bypass?

Does it depend on type of controller - I have an AllComponents Ontrack unit

 

This could also apply to other dmu types, or pairs of class 20  locos.

 

Has anyone tried it?

[seahorse]

Thanks for your quick response - sounds like a good plan, and easier to modify one unit than both.

 

ps - on reflection, "free-wheeling" was a bad choice of words - I really meant operating with less power than the front unit, so that the couplings are always in tension

[DCB]

I you have an "OnTrack" controller there is something very wrong if the power bogies move at different speeds, do they both have the same gearing? Some people use Triang TT singke start worms on Blue Pullman type power bogies for improved slow running,  A tired magnet may also cause poor running, Super Neo magnets are really effective, I get mine from scrap Disc Drives.

 

A freewheel would be difficult, make that virtually impossible with worm drive bogies.  

 

For a diode solution I think I would try a standard 1 amp diode (1N400 from memory) connected parallel with two similar diodes in series connected in reverse, so it get's 1 diode drop (0.7 volt?) for forward and twice as much (1.4 volt?) reverse.

 

In the past I have played HSTs with my son with two Triang Transcontinental Single ended diesels one each end of a three or five car set of Transcontinental coaches and even a scale 150 mph around 15 " curves failed to derail it with no mods from standard at all. Sadly he has grown out of this but In still find it fun!

 

What does cause problems are traction tyres as they make the drive very harsh especially on worm drive bogies like the Hornby HST etc

[34theletterbetweenB&D]

Balancing the two mechanisms with a small network of anti-parallel diodes may well be a winner. Easiest to test the two power cars alone if you temporarily disable the couplers (piece of tape or similar), so that you can trial them close together for comparison purposes, without having to continually uncouple them.

 

If going to this amount of trouble, and since it is a fixed formation train, I would run wiring the length of the train with plug and sockets either end, connecting the pick ups in the power cars. No chance of one end losing power while the other is going full tilt, crash, bang, wallop. Unless of course c,b,w is a major part of the fun.

[seahorse]

Thanks for the solutions, and I hope it will prove useful other people as well. My Pullman set is only an occasional visitor to the layout, so I can't hard-wire it, but I like the diode ideas

[Colin_McLeod]

I hard wired a Triang 3 car dmu (2 power cars and centre car) and it ran very sweetly with the resulting 8 wheel pick up

[jonny777]

I have a Triang/Hornby Midland Pullman with three centre cars ( refitted with modern wheels). It runs better pulling than pushing. So I have bought another motor unit. They are not quite matched so it still runs better one way than the other, with the centre cars giving an uncomfortable ride for my "passengers".

 

From what I remember of contemporary reports, an uncomfortable ride for passengers is quite realistic.

 

If one engine was revving slightly faster than the other the ride was said to be very jerky when accelerating.