Coupling

[smudga331]

I'm a tad new to all this, however, I remember I used to catch a train to Colchester (from Harwich) every friday at just before 4pm to see that a friend got to Colchester safely. (We were only 15 ). But I have always remembered that my train connected to another from Ipswich (always 321's 4 car from Harwich and 8 car from Ipswich) and I always used to wonder what the two drivers coupling the trains were looking for once connected. I remember on one occasion one asking "how does it looks?" to which the other responded "it looks ok to me but im not taking it up to London, so best you take a look"....on other occasions i remember drivers saying it was "all wrong" and to "start again" but I wondered if anybody knew what they could see with the naked eye to tell them this?

Secondly, im not too familiar with the working of couplers and have always been intriegued to know how they cope with such a huge weight? (particularly on 321's and 360's and the working difference between interlock and Dellner)

I'm sure a lot of this is simple common knowledge to most, but has bugged me in the past, so apologies if im missing something obvious

 

[O L Leigh]

It's a Tightlock coupler, not an interlock. Interlock is something different.

Tightlocks are a kind of knuckle coupler. In order that they are locked closed a locking pin must drop on both coupler heads. These in turn operate a "butterfly" or mechanical tell-tale that will pop out from the back of the coupler heads to show that both locking pins have dropped correctly and that both couplers are correctly locked in their coupled positions. Primarily this is what the drivers will be looking for between coupled Cl321s or other Tightlock equipped units.

If you don't get both "butterflies" out you won't have a secure coupling and there is a chance that the units could come apart on the move, so you would need to take remedial action to deal with this. This could be squeezing up tighter to the other unit, "shaking" the couplers by repeatedly applying full power and then shutting off to encourage the locking pins to drop or, if all else fails, uncoupling and starting all over again. There is another option if you have one really reluctant locking pin and that is to get between the units and close and lock that coupler manually before attempting to couple up. Provided that at least one Tightlock coupler is "open" you should be able to couple even if the other one is already locked into the closed position.

Delners work on a completely different principle using cone and pocket gathering structures to ensure correct alignment of the coupler heads and sprung latches to give the mechanical connection between units. These coupler don't have any mechanical tell-tales for the driver to check. Desiro units like the Cl360s that AGA operate don't even allow the driver to conduct a pull test to ensure that the mechanical connection is sound. Once the two units have made contact the driving controls are deactivated and the onboard computers take over to complete the coupling process. However, Delners are less likely to give any mechanical problems than Tightlocks. If you've managed to drive onto another unit the chances of the coupler failing to latch are very slim indeed.

Unlike Desiros, Electrostars do not deactivate the driving controls once contact is made with another unit so the driver is still able to carry out a pull test. I have yet to hear of any Delner equipped units coming apart in service, although this has happened more than once with Tightlocks.

As for the coupling forces, these are actually very modest. Provided that all individual units within the train are working correctly they should all be accelerating and braking at roughly the same rate. Therefore the forces acting between the couplers will be slight. But even when you have to rescue a failed train the couplers are sufficient to cope with the forces acting between units.

One of the great advantages of rail compared to road are that rail vehicles have a much lower rolling resistance. Therefore, once the initial inertia of a stationary vehicle has been overcome it takes relatively little force to accelerate or at least maintain the state of motion. "Strong men" have pulled rail vehicles with their teeth before now, so the forces that must be contained by the locking mechanisms in each coupler type are well within the capabilities of the structures used. As an example, the mechanical portion of the Delner autocoupler is known as a Scharfenburg coupler. These couplers are used at the outer ends of Eurostar trains and have been proven to be stong enough for entire loaded Eurostar trains to be hauled out of the Chunnel into St Pancras by Eurotunnel's fleet of diesel locos.

O L Leigh

 

[jopsuk]

In the US similar couplers to the Tighlock are used almost universally on massive, heavy, freight trains where the forces through the couplers when starting will be vast compared to almost any situation in the UK

 

[matchmaker]

Going back a long time ago when I was a volunteer on the Severn Valley Railway I was introduced to the joys of coupling coaches. Nothing automatic in these days and I can assure you that all parts of a coupling, be it buckeye or screw are blo**dy heavy.

The worst part was where a buckeye had been dropped to couple to a screw fitted coach and you subsequently had to lift the buckeye again! You just hoped that there was a handy bit of point rodding nearby to use as a lever...

Then vacuum and steam heat pipes, jumper cables and if screw coupled you also had to couple up the gangway connections.

Even more fun if you were doing it at night

<Yorkshire accent> Young people nowadays - just don't know they're born! :roll:

 

[smudga331]

Wow! A detailed string of responses all of which have allowed me to understand this a lot better, thank you all for your time and effort in replying.

7 Years worth of pondering has finally been answered

Thanks again!

 

[SpacePhoenix]

https://www.youtube.com/watch?v=kOY3lFO8XMg

That's a youtube vid that shows how tightlock couplings are operated