S stock DM coupler handedness

Interesting question (and a new thread is a good idea ).....

because they will have to be able to be compatible with A and C and D stock in emergencies in the short(ish) term. Or is it all down to the presspahns??

That was what I initially thought too, but despite the apparent mechanical symmetry of the coupler, I wasn't certain just from the visuals. Plus, I wasn't sure if emergency comms would be carried over the coupler, or if the existing procedures regarding Connect handset-to-handset comms would be employed during pushouts.

That is a great picture, though!



Indeed - I wonder how big such an adapter would be and where it would be stored.

Hello, sorry for my late arrival! Ok...

There was a plan a few years back to go for a completely new type of coupler and just put up with the pain in the interim (having to have emergency adaptors strategically placed on the railway) but that idea was dropped. What we have now is a standard wedgelock coupler that is compatable with 'A', 'C', and 'D' couplers.

The couplers are not 'handed' and it is possible to couple 'S' to 'S' mechanically and pneumatically but not electrically. In order to achieve through communications a 'communications jumper cable' (Comm's Jumper) must be utilised. This jumper can be connected via the the connectors on the front of the train situated either side of the 'M' door just below the level of the bottom of the window and adjacent to the tail lights. It is a simple case of unscrewing one of the covers and attaching the jumper, although it is necessary to attach the bridging plate (part of the detrainment device) to stand on first. There are two connectors either side of the 'M' door in order to prevent the need to cross the cable over the couplers and create a tripping hazard, so you just pick whichever connector takes your fancy and select the adjacent one on the other train.

Which way does the door open? Is it not possible to just reach around the door frame to do this? TVM.

Based on the picture, I expected this to be the case.



Is this cable solely for comms, or does it carry the control signals to release the brakes on the unit 'under tow'? Or is that done solely with pneumatic signalling on the coupler face?

if you look carefully on the "full frontal" photos in the Met Line section you'll see the covers for the connector. They are unscrewed rather like jar tops (although wilth less force) plugging in the connectors involved no Electricity at Work issues; the voltage will be very low. This technique is a copy of what has been done on a number of modern fleets.

Of course, the challenge for the engineers was to manage affairs so that push-outs are rare! But one can "never say never"!

They are the same height.

Just really quickly, as I am knackered after spending two days racing between Neasden, Derby, and Nuneaton for various different 'S' related tasks - We coupled car 5117 to car 21100 on Wednesday morning on 29 road in Neasden. The two trains coupled and uncoupled without any issues whatsoever.

Colin, I took lots of video and stills!

It all depends what the defect is that requires an assisting train to be utilised. An assisting 'S' can mechanically couple to another 'S' and then throw air accross and apply/release the brakes accordingly from the healthy train but you would not want to do that if the defective 'S' had a burst of some sort. That said, you will not need to couple to another 'S' for any form of burst.