Here We Go... Miscellaneous Conversions To P4

Armchair Modeller
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Here We Go... Miscellaneous Conversions To P4

Postby Armchair Modeller » Sat Jun 10, 2017 11:37 am

Whilst the layout is up and running, I have been tempted to try all sorts of stock to see what runs and what doesn't. So far I am very encouraged by the results and am convinced that the track is runnable. With its unusual pointwork, reverse curves and exaggerated superelevation, I fully expect some of the less stable or more inflexible items to derail at some place or other though. I will probably pick up problems that most people wouldn't get on a more conventional layout. That is why I am so keen to rigorously test things out. Any RTR stock has to pass the test too. If it doesn't run well, then I need to deal with it.

First on the naughty step is this one...

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I bought it when they first came out a few years ago. Then, I had visions of building a small BR 1960s passenger terminus. I converted it using Branchlines wheels. Over most of the trackwork, the whole thing runs very well, but the motor bogie occasionally derails in a couple of places. Removed from the body, the motor bogie runs fine. The unpowered trailer car runs superbly, even at relatively high speed. I suspect the way the motor bogie is mounted in the chassis is to blame. The attachment is not designed to deal with the more extreme changes in my track using P4 wheels.

My first reaction is to think about fitting a High Level Lowrider motor bogie. That would also mean I could get rid of the horrible and unsightly weights surrounding the Bachmann motor bogie. Watch this space!

I also had a look at a Heljan AC Railcar. I bought this one for Neversay. I had visions of imagining it as a light railway version of the BR design by adding cowcatchers , roof rack etc and repainting it. As soon as I first got it out of the box though, I realised it was just too nice to spoil, so it will have to stay as a BR railcar. I haven't a clue what excuse I can use to run it on Neversay, but I will still have a go at converting it to P4.

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In principle, the conversion looks very simple. The axles are 2mm diameter, so no special components should be necessary. The only concern so far is that there is not enough space for P4 wheelsets. A little bit of surgery will be required to obtain sufficient clearance.

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Russ Elliott
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Re: Here We Go... Miscellaneous Conversions To P4

Postby Russ Elliott » Sat Jun 10, 2017 9:14 pm

Armchair Modeller wrote:Over most of the trackwork, the whole thing runs very well, but the motor bogie occasionally derails in a couple of places.

Bachmann pitch freedom in its bogies is good, but their Achilles heel is usually a lack of roll freedom, which I suspect explains why the drive bogie is ok on its own, but can misbehave on your superelevations when acting in conjunction with the whole chassis. A bit of vertical slop in the axle bearing containers may or may not help.

Armchair Modeller
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Re: Here We Go... Miscellaneous Conversions To P4

Postby Armchair Modeller » Sat Jun 10, 2017 9:59 pm

Thanks, Russ. Your explanation is far clearer than anything I could have managed. Giving the axles a little freedom may well be a good way to proceed.

Looking at the pickup strips and the way they fit into the axle bearings, I am almost tempted to consider some kind of sprung suspension. It is not an urgent thing though.

Always useful to put ideas and problems up here as someone is bound to come along with some kind of useful insight. :thumb

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Russ Elliott
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Re: Here We Go... Miscellaneous Conversions To P4

Postby Russ Elliott » Sun Jun 11, 2017 10:20 am

Armchair Modeller wrote:I am almost tempted to consider some kind of sprung suspension.

The Bachmann drive bogie doesn' lend itself to a conventional springing route without a drastic rebuild, but, thinking off the top of my head, I'm wondering whether a slither of 2mm neoprene between each bearing and its plastic frame might provide some help. The drive bogie's 200g weight would compress it a little bit.

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Tim V
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Re: Here We Go... Miscellaneous Conversions To P4

Postby Tim V » Sun Jun 11, 2017 10:39 am

Or you could modify the non powered bogie to provide roll movement.
Tim V

Armchair Modeller
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Re: Here We Go... Miscellaneous Conversions To P4

Postby Armchair Modeller » Sun Jun 11, 2017 11:12 am

Thanks again for all the suggestions.

Tim - the other bogie is already free to move in all directions and seems to behave very well, as do the two in the trailer. I think the problem is entirely due to the way the motor bogie is mounted in the body, as Russ indicated. Not a problem for most people but my deliberately 'extreme' track has sussed it out.

I will pull the body/chassis apart again later to see what the possibilities are, time permitting - but I need to get on with a few other much higher priority things first.

Armchair Modeller
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Re: Here We Go... Miscellaneous Conversions To P4

Postby Armchair Modeller » Sun Jun 11, 2017 11:33 pm

Having tried a few ideas this evening, I think my best approach will be to fit a High Level Lowrider bogie to the DMU. It will allow the pivot to be placed much lower down. This should allow the bogie to ride much better. Then, I can get rid of the horrible black box covering the bogie mount and motor too.

The old motor and bogie will not be wasted in the long run. I think I can adapt them for another project, where the pivot is not required.

I will try and finish a few other things first though. :D

Thanks again for all the suggestions :thumb

Terry Bendall
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Re: Here We Go... Miscellaneous Conversions To P4

Postby Terry Bendall » Mon Jun 12, 2017 6:58 am

Armchair Modeller wrote:I think the problem is entirely due to the way the motor bogie is mounted in the body, as Russ indicated.


I would agree with this. On some diesel models I have had to loosen the pivot screw to give sufficient movement.

Terry Bendall


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