No.53 Some further thoughts on the ride height of Bachmann Thompson Brakes and Hornby Gresley Brakes

This Post follows on from comments received on the last Post.  As bought I think there is a significant difference in the ride heights of the Bachmann Thompson coaches and the Hornby Gresley coaches.


Early Bachmann Thompson BG compared to super detail Hornby Gresley



I am indebted to John who commented on my previous Post describing a means of remedying the situation.  I am not sure what I was thinking about when I said that there were differences in ride height between ‘old’ and ‘new’ Bachmann coaches – well maybe marginally.  To clarify matters I am posting here a few comparison pictures.

Recent Bachmann Thompson BG compared to super detail Hornby Gresley


The view above shows the latest Thompson BG compared to the super detail Gresley.  The buffer height seems acceptable but the Bachmann corridor connector looks way too high.  Roof heights seem similar.


Recent Bachmann Thompson BG compared to Bachmann Mk1 BG



This time I have compared the latest Thompson with a Bachmann Mk1 BG – the Thompson is riding noticeably higher.


Bachmann Thompson Bogies, Early on Left, Latest on Right



The view above compares the two types of bogie used by Bachmann on their Thompson coaches.  I could imagine that the centre section of the newer bogie on the right is more depressed – leading to a lower ride height.  However I do not have the measuring equipment available to confirm – either way it does not appear to be significant.  Within the limits of my steel rule the height of the moulded pivot on the underside of early and new Bachmann underframes appears identical.


Recent Bachmann Thompson BG (with old bogies left) compared to Early Bachmann Thompson BG (with new bogies left)



Just to confuse I have swapped the bogies (new to old) between the two Bachmann Thompson BGs.  The view above would seem to confirm that fitting the ‘new’ bogies to the early BG lowers its ride height relative to the Thompson BG fitted with the ‘old’ bogies (but only marginally).


Hornby Super Detail Gresley compared to Bachmann Mk1 BG



Finally another comparison picture, Hornby Super Detail compared to Bachmann Mk1 BG – in my opinion not a lot wrong here with these two vehicles - well height wise.



To summarise – yes the Bachmann Thompson coaches both new and early have ride heights probably too high.  The latest Bachmann Thompson bogies might offer a slightly lower ride height but to make any meaningful difference either the bogie of the underframe needs to be altered, perhaps along the lines suggested by John.

Now what about the gap between the coaches? 

Addenda 

I have tracked down a set of drawings for the Thompson Coaches in the April 1964 edition of the Model Railway Constructor. You can view the drawings here. I have compared a few dimensions off the drawings with measurements from the most recent Bachmann Full Brake:

8364747377_5f5409b011.jpg

The comparison would see to confirm that the top of the underframe is too high which is reflected in the roof level, underside of corridor connector and top of sole bar all being 1mm higher than the prototype dimensions.

Just as an aside the bogie wheel spacing for all the Thompson coaches is given as 8'-6" with the exception of the Full Brake where the wheel spacing is given as 8'-0" - why?

What is 1mm (3 inches) between friends. I guess I should file / remove 1mm from the shoulders of the bogie pivots!

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