Using Marklin mechs for Aussie prototype diesels

[scaro]

Hi

Doing a bit of measuring of the Marklin 8804, 8864 off-centre cab diesel last night.  I believe that it could be used to power a couple of Victorian locomotives. 

For those who don't know (and why would you?), Victoria is a state of Australia and is the prototype for Adrian's work on T-gauge - you can see the gallery of images over on David's T-gauge page. 

For a start there's this, which is a bit of a no-brainer,  given that the symmetrical wheelbase of the W class, the only major variation from the Marklin chassis, is concealed behind side boards:

http://www.victorianrailways.net/motive%20power/wdie.html

And then this, which is a rebuild of the T class (ie, Adrian’s blue and yellow T gauge Australian diesel). 

http://www.victorianrailways.net/motive%20power/pdiesel/pdie.html

The 8804, 8864 mech could be shoehorned into the cab of the P class, but the outer axle would have to be removed and a new rear truck built. Further, there would not be room for the 'motorised bogie' thus created to swing.  I believe that having a loco with one rigid (ie, non swivelling) bogie and one that swivels on a bolster is a no-no.  Is that correct ? 

Could the rear truck be done as an extended pilot, in effect making it a 'reverse 4-4-0' with a rigid set of driving wheels and a swivelling ‘pilot’ truck ? 

Would such a chassis run any better than a wino with bad feet ?

cheers

Ben

[bambuko]

Ben, quoting from excellent "An introduction to Split Frame Chassis Design" edited by Nigel Cliffe:
"...empirical observation suggests that excellent running can be obtained with drive train to one bogie only, the other simply carrying weight and picking up current..."
I think the main issue will be weight distribution?
Why not experiment on some cheap and nasty N gauge loco (bound to be cheaper and easier than Z) and only if succesful, move down scale?
It should be possible to disconnect the drive to one bogie, without much alterations?
I don't think anybody is likely to give you an answer - you need to experiment ;D

[DKS]

Ben, I'm not entirely certain, but I think--depending on your ambition and skill--you could hack down an M-T GP9/35 (or, for better width, an AZL GP7) chassis. It would mean cutting up and reassembling the metal parts and reworking the drivetrain, but it might be do-able. (I've been tinkering with an idea for a Z scale MP15DC, which might be similar in size). The only stopping point might be the truck wheelbase--depends on that they are on the T class.

[scaro]

Ben, quoting from excellent "An introduction to Split Frame Chassis Design" edited by Nigel Cliffe:
"...empirical observation suggests that excellent running can be obtained with drive train to one bogie only, the other simply carrying weight and picking up current..."
I think the main issue will be weight distribution?
Why not experiment on some cheap and nasty N gauge loco (bound to be cheaper and easier than Z) and only if succesful, move down scale?
It should be possible to disconnect the drive to one bogie, without much alterations?
I don't think anybody is likely to give you an answer - you need to experiment ;D

Hi Chris

I think what Nigel is referring to there is the case where the one powered truck is able to swivel or move a bit.  In the case I'm speaking of, I do not think the Marklin motor when put into the P class cab will have any room to swivel, or at least not much. The P class cab is about the same width as the 8804/8864 cab.  But I have an 8864 and it isn't doing anything much at the moment -  I just bought it because it was cheap -so I think I'll try it. 

Ben

[bambuko]

...I do not think the Marklin motor when put into the P class cab will have any room to swivel...

Ben, unless I am confused (and that's my usual state as I slowly descend into decrepitude  ;D )
I never heard about motors needing to swivel? - it's only the boogies that swivel ?
and anyway 8864 is three axle thing with no bogies to swivel at all?

[scaro]

Chris

Yeah, I should explain myself.  The 8864 has no bogies, as you say it is a three axle thing.

My idea is to remove one of the axles, leaving two axles, which with the motor, would comprise a 'motor bogie' that would sit inside the P class cab. 

Then a second, trailing bogie would be needed at the rear of the P class loco. 

My concern, based on previous discussion about this, is that a fixed motor bogie like this is asking for trouble.  As it cannot pivot, due to the Marklin motor being a snug fit against the cab walls, ergo it would tend to pull the whole shell out too far when going round curves and so derail the trailing truck. 

But I thought one might be able to get away with it if the trailing truck had the same freedom to move as a steam loco pilot truck.  For example, a 4-4-0 has rigid driving wheels which do not pivot, but the pilot truck does not derail.

Anyway, too much talking.  I should try it.

David, I believe Joe D'A has already discussed an MP15DC as you suggested, and there was a photo of the chassis in the Yahoo Z forum.  It's powered at one end only I think. GP trucks are 9' whereas the P and T class trucks are 8' wheelbase, being GM export models and somewhat smaller than domestic US locos.  I assume one may have to accept living with that, as I'm not sure an MT GP9 could have its trucks shortened . . .

Ben

Ben