Notes on B&B couplings

[John CutlerParticipant]

Some short notes on B&B couplings

I decided to test these after tearing my hair out with Flippems.

Refer to the EMGS Manual 9.1.1 (8) for the installation and operation instructions.

The B&B etch (partly used). Note the latch etch is between the loops.

Here are my observations:

1.       The fold lines are not etched. It is recommended to lightly score these before cutting out the etches. The advice on RMWeb (for 2mm scale couplings) is to score them on the outside of the bends. I recommend the score lines should be on the inside of the bends; I cannot believe that the majority of etched kit designers have got that wrong.

2.       I recommend drilling out the pivot holes for the latch to 0.7mm to ensure they are free to rotate; I found the loops did not need this. This also makes the latch easier to locate in the lugs.

3.       Fitting the pivots into the lugs is a pain, especially the latch (but nowhere near as difficult as on the Flippem). A tip is to make the bend for the lugs on the main etch slightly away (outward) from the main body so the latch and loop are easier to fit between the (wider-spaced) lugs. I am not sure about this as it slightly alters the heights of the latch and loop relative to the opposing hook.

4.       The B&B is much quicker to assemble than the Flippem/Dingham (no surprise there) but slower than the AJ (but to be fair I have had more practice with AJs and their derivatives).

5.       I discovered that the plastic coupling hook on one of the RTR test wagons interfered with installation and potentially restricted the latch movement.

6.       I suspect that if said hook were removed, closer coupling could be achieved.

7.       Despite the effort of ensuring the coupling hooks were at the same height above the rails, coupling up reliability was poor at less than 50%. Part of the problem was traced to a latch not moving freely but even after correcting that, performance was not good.

8.       By contrast, uncoupling with a magnet was almost 100% effective.

9.       Following Iain Rice’s comments, I expected the B&B to unintentionally uncouple in transit over my bodged trackwork. This did not happen despite a lot of coupling waggling (a bit distracting)! Maybe my permanent way is not as bad as I think…….

10.   Delayed uncoupling worked provided the latch was free to turn.

11.   The buffing plate on the hook means they can be set forward of the buffer faces (the recommendation is 1.5-2mm) so buffer locking on wagon propulsion is avoided. The coupling is strong enough to take this loading in most cases but a glued fixing may not be.

12.   The pre-blackened etches are good news. One less job and a reduced risk of gumming up the works on blackening.

13.   The B&Bs are much more visually obtrusive than the Flippem/Dingham or the AJ.

Note the comparison with the mostly hidden Flippem on the left, which does not flop up and down either!

I was very disappointed with the coupling reliability. I am sure that with a lot more investigation and adjustments, this performance can be improved. But if the B&B requires such precision, it is no better than the Alex Jackson and derivatives which are much less obtrusive (and cheaper!).

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