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DMUs – Close coupling and corridor connectors for Bachmann Types


Silver Sidelines

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Following my posts dealing with Collett and Hawksworth coaching stock I am moving forward a few years to talk about Bachmann DMUs, Class 108, 105 and Derby Lightweight.

 

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Location – location!!!

 

When I acquired my first Bachmann Class 108s I immediately set about closing up the gap between the units. The Bachmann 108s have sprung buffers and it is possible to draw the two coaches together such that the moulded corridor connections are almost touching yet still allowing the unit to negotiate relatively tight curves.

 

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As bought (bottom) modified (top)

 

The solution that I adopted was to replace the Bachmann couplings by a plain bar filed down from a 30mm long piece of code 100 nickel silver rail.

 

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Original Couplings (top), modified coupling bar (middle), 30mm length of Code 100 nickel silver rail

 

The nickel silver rail is filed down so that it is a force fit into the original Bachmann Coupling Pocket. The 30mm length works on my layout with Peco Medium Radius points. If the curves were smaller radius then the units would need to be gently eased further apart. If the minimum radius was larger then conversely the rail could be pushed further into the coupling pockets. This modification is straight forward and totally reversible should the units need to be sold.

 

The Bachmann Cravens (Class 105) also have sprung buffers and the same approach can be used.

 

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When Bachmann introduced their Derby Lightweight Units I tried the same approach – however I missed the fact that the buffers were not sprung. As can be seen in the above picture, replacing the couplings with a fixed bar still leaves a massive gap if the units are still to negotiate 36 inch curves.

 

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27mm high, folds at 8,8,10.5,13,13,13,10.5,8,8mm and indents 2.5mm top and 1.5mm bottom

 

One solution is to fill the gap with corridor connectors. My first attempt was to make connectors to the dimensions I used earlier for the Bachmann Collett coaches. This was not a good idea. The moulded plastic connectors on the Derby Lightweight units are relatively narrow. I have suggested some more appropriate dimensions beneath the picture above.

 

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Ready to push the units together

 

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Class 108 (bottom) Derby Lightweight Finished (top)

 

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Ready to Depart?

 

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Close Up!

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Now that is handy. I'd been pondering a "closer" coupling of my 105... but got distracted by the main 47 project again. Useful stuff this, so thanks for sharing... I'd better bookmark this one.

Jon

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Ray,

thanks for the comment... my 47 project (the distraction) is blogged too here Somewhat of a lengthy project, so the Craven was to be a nice simple project but will be on hold for a while.

Jon

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For Jon and Metroland I have added an Addenda to the original Blog Post with some pictures of my Cravens. 

 

When compared to the Class 108 units my Cravens need an extra millimetre of clearance between the coach ends to prefvent buffer locking on Peco Medium Radius Points.

 

Regards Ray

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Thanks Ray. I'll be P4'ing mine so the min radius will be quite long... hopefully this means I can keep them tight, but thanks for the additional info, which is greatly appreciated.

Jon

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For Jon and Metroland - yet another update!

 

I have moved the 'Addenda' to a completely new 'Posting' - as you will see the Bachmann Class 105 has smaller buffers than the Bachmann Class 108 which explains why the buffers on the Cravens will lock up on tighter curves. I should have spotted that earlier!

 

Ray

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