Wanting to convert some Bachmann 12 ton ventilated van

[MarkG]

Hi
I have some of Bachmann's 12 ton ventilated vans that I wish to convert to P4 using compensation units. (these will be the first model that I'm converting to P4)
It seems there are a few types to choose from so any advice would be welcome, as I would like to detail as much as possible under the body.
Thanks
Mark

[Russ Elliott]

Bachmann wagon underframes do vary, and I'm not familiar with the particular ones you've got. If you want to convert them for use with compensation units, you'll need to clear the space required. The diagram below gives the typical space you'll need if using MJT outside W-irons. The Scalefour Society units require fractionally less height clearance if my memory serves me correctly. The vertical space to be cleared is highest for the rocking-unit end, and extends higher than the top of the chassis, so the best plan is usually to hack out the whole area required with a piercing saw. Bachmann solebar spacings vary.

comp-w-iron-clearance.png

You probably won't be able to salvage the spring/axlebox from the Bachmann W-iron because of the type of plastic used, so it will usually be quicker to mount replacement MJT or other spring/axlebox castings. It may be possible to retain the Bachmann spring when clearing the lateral distance, in which case new boxes are all that is required, and these should be mounted on the W-iron itself, ensuring that there is enough recess for them to clear the spring when rocking.

axlebox-cuts.gif

axlebox-cuts2.gif

[David Knight]

Mark, you might want to have a look at this article first; http://www.clag.org.uk/rewheelingwagons.html
It all depends on how much of a hurry you are in to get working stock.

HTH

David

[MarkG]

May I thank Russ and David for the advice.
Mark

[Terry Bendall]

This job was done as one of the tasks in the first two of the Society's beginners' workshops using the 12 ton ventilated fruit van (38-181B). There are several ways of doing the job. The way that we selected was to use an MJT inside bearing rocking W iron. Using this avoids having to remove the existing plastic W iron, bearings and springs. It is necessary to cut away the floor and fit a piece of plastic inside so that the ride height is correct. It was also necessary to pare away some of the inside of the plastic w irons on the rocking end to give clearance. At the orther end the P4 wheesl were simply fitted into the existing plastic bearings.

An alternative is to use the Bill Bedford sprung bearing system but this will probably take a bit more time.

Of course if the track is fairly level, you may be able to get away with no suspension or compensation at all.

Terry Bendall

[Russ Elliott]

For MJT inside units with 12.5mm dia wheels, the rocking unit needs 15.7mm headroom above rail level, and the fixed unit needs 14.7mm above rail level.

[John McAleely]

This job was done as one of the tasks in the first two of the Society's beginners' workshops using the 12 ton ventilated fruit van (38-181B). There are several ways of doing the job. The way that we selected was to use an MJT inside bearing rocking W iron. Using this avoids having to remove the existing plastic W iron, bearings and springs. It is necessary to cut away the floor and fit a piece of plastic inside so that the ride height is correct. It was also necessary to pare away some of the inside of the plastic w irons on the rocking end to give clearance. At the orther end the P4 wheesl were simply fitted into the existing plastic bearings.

There is a picture of my conversion from the workshop here: http://scalefour.org/forum/viewtopic.php?f=39&t=765:

[grovenor-2685]

See also comment from Bill Bedford in the Guest Book.
Keith

[craig_whilding]

I think Masokits may do some sort of inside bearing springing unit though the Bill Bedford ones replacing the w-iron will look better.

Unless the wagons are travelling large distances they will be better off with P4 wheels in the existing chassis than bothering to fix compensation. I dont think anyone should need to fit compensation anymore unless they have a large stash of parts still.

[Russ Elliott]

The clearance space for BB W-irons is different from that required for outside rocking W-irons. BB units require 24.5mm lateral and 22mm longitudinal solebar space. BB units also require less vertical space, so extra excavation/platework above the chassis top isn't required. The longitudinal space will usually mean hacking out some of the brake gear on most RTR wagons, and the RTR W-iron, if it can be retained at all, will need slotting for the bearing movement. The brake gear might need moving anyway, depending on the particular RTR wagon being converted. On some older Bachmann wagons, it might be easier to throw the whole chassis away and fit a sprung replacement - some Bachmann W-iron spacings do not allow P4 wheelsets to be inserted easily. I would imagine the Bachmann Presflo could be a bit of a challenge!

[craig_whilding]

I would imagine the Bachmann Presflo could be a bit of a challenge!

Yeah that certainly isas I had a look at mine a while back to think about etching something. There is also all the fine detail that really needs removal before the job could begin. Beautiful models though..

[Captain Kernow]

The clearance space for BB W-irons is different from that required for outside rocking W-irons. BB units require 24.5mm lateral and 22mm longitudinal solebar space. BB units also require less vertical space, so extra excavation/platework above the chassis top isn't required. The longitudinal space will usually mean hacking out some of the brake gear on most RTR wagons, and the RTR W-iron, if it can be retained at all, will need slotting for the bearing movement. The brake gear might need moving anyway, depending on the particular RTR wagon being converted. On some older Bachmann wagons, it might be easier to throw the whole chassis away and fit a sprung replacement - some Bachmann W-iron spacings do not allow P4 wheelsets to be inserted easily.

In the end, that's exactly what I did with a Bachmann S.R. box van - the chassis would have required too much hacking about and it just seemed simpler to build a new chassis, based around BB springing units.

[Captain Kernow]

Unless the wagons are travelling large distances they will be better off with P4 wheels in the existing chassis than bothering to fix compensation. I dont think anyone should need to fit compensation anymore unless they have a large stash of parts still.

Then why is the Society sponsoring workshops that teach folk how to fit internal rocker compensation, Craig?

It still has a place, it's certainly less time consuming that fitting full springing, although I will admit that if you're retaining the R-T-R chassis components, it probably won't look quite as nice as replacement etched parts etc. It may make the difference (as compared with a fully rigid wagon in P4) between a wagon staying on slightly lumpy track, and falling off each time...

[Russ Elliott]

Then why is the Society sponsoring workshops that teach folk how to fit internal rocker compensation, Craig?

Good question.

<devil's advocate mode on...>

It's a bad combination of the least amount of preparation, the least amount of tools, the least amount of thinking, and the least amount of work/alteration to provide the least effective result but ticks the "it's so easy" PR box.

The next logical step would be "just fit these EM wheels and you'll be ok"...

Devil's advocate mode off, I've used internal rockers (we all have our pragmatic/lazy tendencies where we can't stomach a major rebuild). Good for brake vans though: stops them rolling about and keeps a train's couplings taught.

[Captain Kernow]

I've used internal rockers. Good for brake vans though: stops them rolling about and keeps a train's couplings taught.

That they are!

we all have our pragmatic/lazy tendencies where we can't stomach a major rebuild

Pragmatism trumps lazy in my book, either way, it almost always comes down to how much time there is for anything....

[Brinkly]

Pragmatism trumps lazy in my book, either way, it almost always comes down to how much time there is for anything....

I've found that it is quicker and the running quality is better with a complete chassis rebuild, rather than trying to faff about with the rockers on an RTR chassis!

... perhaps nearly removing my finger tip a couple of years ago has helped support this theory!

Regards,

Nick

[Captain Kernow]

Pragmatism trumps lazy in my book, either way, it almost always comes down to how much time there is for anything....

I've found that it is quicker and the running quality is better with a complete chassis rebuild, rather than trying to faff about with the rockers on an RTR chassis!

Interesting.

The only reason (or the main reason, at least) that I've done any internal rocker compensation is that it was quicker than a chassis rebuild!....

[Terry Bendall]

Then why is the Society sponsoring workshops that teach folk how to fit internal rocker compensation, Craig?

The content of the first workshop was the subject of some debate by the committee, and we did not all agree, but we ended up with a range of tasks that we felt were useful to the beginner. We covered the use of an inside bearing W iron because it is a fairly simple and straightforward way of doing a conversion. What we did as well was to emphasise that there are several other ways of helping vehicles to stay on the track and showed examples of these methods and mentioned that sometimes you can get away without any springing or compensation. As others have said, a pragnatic approach to help those new to working in P4 to get started.

If you have read the Chairman's Doghouse in the curent issue of the News you will know that the good folks in the Bristol Area Group are going to run a workshop later in the year and their ideas are quite different from the first two. That is fine because they are doing the course and I am sure that it will be eually successful and useful.

Terry Bendall

[Captain Kernow]

Then why is the Society sponsoring workshops that teach folk how to fit internal rocker compensation, Craig?

We covered the use of an inside bearing W iron because it is a fairly simple and straightforward way of doing a conversion.

As others have said, a pragnatic approach to help those new to working in P4 to get started.

I do agree with this approach, if it helps people get started and thus gain the confidence to progress to more sophisiticated solutions.