Pocket or Plug?

[Kingfisher200262]

A thread on the General Discussion part of this forum, relating to Class 317 problems on Stansted Express caused by build up of snow has prompted me to ask this question.

So, for an EMU or DMU, with 1/3 - 2/3 doors, doing commuter work, which is more appropriate?

Exploring the pros and cons of each to stimulate the discussion: -

Pocket

For: Simplicity, speed of opening / closing, easier to set up, low cost
Against: Vulnerable to jamming (e.g. build up of snow!), harder to seal, impede into passenger space

Plug

For: Reliability, good seal to body, improved aesthetics
Against: Expensive, more complicated to set up, slower opening / closing

Would like to hear the views of the operators and maintainers here, and feel free to challenge the above suggested pros and cons (and add to them).

 

[Wyvern]

Sliding pocket doors can usually be larger allowing quicker boarding and alighting for commuter work

Not the OP specifies commuter trains - plug doors may have less wind resistance for higher speed longer distance trains.

 

[Kingfisher200262]

Nice one.

 

[jopsuk]

Depends what sort of commuter service- outer (less stops, higher speeds, longer journeys) plug is better, inner (Metro-type) sliding wins. There did seem to be a move in the nineties/early 00's to go plug for everything, but the 376 and 378 show that lessons were clearly learnt there.

 

[Pumbaa]

Plug are far more aesthetically pleasing. The seal for air pressure etc is far better than pocket doors, and external hung doors. While lessons may appear to be learnt, the 375/377 closing plug doors are just as quick to close and open as the pocket doors on the 376. Wider plug doors are also being implemented into the Desiro city design.

To me, it's a no brainer. Plug every time!

 

[poshbakerloo]

Plug doors look much better, but for VERY busy routes they arn't as good as they almost open into the people standing at each side of the doors, and the open and close slower...

 

[Broken Viking]

[This post moved over from my original one in Nowt Trains east Anglia in the NR General section.]

I'm interested in the reference you made to door problems, as I'm involved in new train design. This raises a question, which I should perhaps raise in the rolling stock section regarding whether pocket doors or sliding plug doors are more appropriate for commuter trains.

Personally, I think the best design of train door I've seen thus far was on the old Mk. 1 rolling stock on the Hamburger S-Bahn. These were "pocket" sliding doors that were opened by passengers themselves, each door having a balance weight hidden in the chassis that was heavy enough to close the door again once released - Similar in a way (But in reverse principle) to the counterweights on a sash window. When the train was departing, the driver simply hit the "Türen Schleißen" (Close doors) button on his panel, which would energise solenoids along the length of the train - Causing the weights to drop, closing and locking the doors in the process.

As a result of this, the doors were extremely fast in operation. As they were passenger operated, only the doors that needed to be opened were opened at a stop...And because the doors were operated via a passengers own strength and gravity, they also required virtually no traction power to operate! 8)

Personally, I think this design would be the best one to look at using...Although to speed up the closing and departure process, I'd suggest replacing the counterweight with a pneumatic ram operated at high pressure (About 5 bar or so) which would reduce closing times to less than 1/10th of a second...As well as giving a heartwarmingly Bloody display whenever a foolish Chav tries to board the train at the very last moment!

Later addendum:
Here's a photo of the type of train and door system that I'm talking about. Ironically enough, this was taken at the platforms of the HVV's newest station Hamburg Flüghafen despite featuring Hamburg's oldest rolling stock!

If I can find any YT videos to demonstrate operation better, I'll add them in here.

Farewell...
>> Death <<

 

[317666]

Pocket doors.

 

[MCR247]

They have them on some Paris metro trains!

 

[aspierail]

It really depends but i would say plug doors are suited to long distance routes and pocket doors are better suited to short/metro type of routes i say.

 

[bengley]

The plug doors on 165s and 166s are really good. They slam themselves shut just as quickly as any pocket doors can.

 

[No Fault Found]

A thread on the General Discussion part of this forum, relating to Class 317 problems on Stansted Express caused by build up of snow has prompted me to ask this question.

So, for an EMU or DMU, with 1/3 - 2/3 doors, doing commuter work, which is more appropriate?

Exploring the pros and cons of each to stimulate the discussion: -

Pocket

For: Simplicity, speed of opening / closing, easier to set up, low cost
Against: Vulnerable to jamming (e.g. build up of snow!), harder to seal, impede into passenger space

Plug

For: Reliability, good seal to body, improved aesthetics
Against: Expensive, more complicated to set up, slower opening / closing

Would like to hear the views of the operators and maintainers here, and feel free to challenge the above suggested pros and cons (and add to them).

Pocket

Plug doors are a real pig to maintain/setup compared to pocket doors. Time which could be spent in other areas IMHO.

 

[Burkitt]

The Japanese use pocket doors on everything from commuter trains with five double doors per carriage to the fastest bullet trains, and they seem to know what they're doing when it comes to railways. The Hitachi Javelins on HS1 have pocket doors and HST2/IEP/Super Express will do too. I understand this preference is due to the superior reliability of pocket doors compared with plug.

External sliding doors haven't been mentioned yet - they work very well on all recent London Underground stock, as well as many other trains with high frequency stops such as the DLR and Paris's new Francilien units.

Aesthetically I prefer plug doors, but on the railway function has to come above form, at least until you reach American levels of incompetence at attractive industrial design, then you need to rethink your priorities again.

Paul

 

[No Fault Found]

The Japanese use pocket doors on everything from commuter trains with five double doors per carriage to the fastest bullet trains, and they seem to know what they're doing when it comes to railways. The Hitachi Javelins on HS1 have pocket doors and HST2/IEP/Super Express will do too. I understand this preference is due to the superior reliability of pocket doors compared with plug.

External sliding doors haven't been mentioned yet - they work very well on all recent London Underground stock, as well as many other trains with high frequency stops such as the DLR and Paris's new Francilien units.

Aesthetically I prefer plug doors, but on the railway function has to come above form, at least until you reach American levels of incompetence at attractive industrial design, then you need to rethink your priorities again.

Paul

Are the 395 Javelins not plug doors?

 

[starrymarkb]

nope! look most odd as they are not flush with the body like European designs

 

[90019]

Are the 395 Javelins not plug doors?

Nope

 

[No Fault Found]

nope! look most odd as they are not flush with the body like European designs

But they do have a 'plugging' action to create a better seal.

 

[kestrel]

But they do have a 'plugging' action to create a better seal.

Nope they have a system when they reach 25-30mph (don't know exact speed) that 'pushes' out the door into the seals so you get none of the banging when another train passes or when you enter tunnels (which is handy as there's a few!) having travelled on them it works very well, best of both worlds!

 

[No Fault Found]

Nope they have a system when they reach 25-30mph (don't know exact speed) that 'pushes' out the door into the seals so you get none of the banging when another train passes or when you enter tunnels (which is handy as there's a few!) having travelled on them it works very well, best of both worlds!

More like 15mph, i'm sitting on one now.

Personally, i would call that 'system' you refer to 'plugging'. The door has movement in 2 seperate planes.

 

[Pumbaa]

More like 15mph, i'm sitting on one now.

Personally, i would call that 'system' you refer to 'plugging'. The door has movement in 2 seperate planes.

Internal hung plug doors as opposed to external hung plug doors.

 

[No Fault Found]

That sounds good. Although they don't plug all the way flush to the bodyside they are still plug nonetheless and have the maintenance issues associated with it.

 

[Mike395]

Indeed, also leads to you getting frustrated if youre a first timer using them and you're in a hurry to get off the train as it takes a second or two to 'un-plug' - just long enough to think nothings happening!