Northern Line: what are the analogue gauges you see on trains?

[ChewChewTrain]

I’m talking about the barometer-looking things that are set in to the seat housing, near the floor. They seem to climb as the train progresses, only to climb more when the doors open, followed by a rapid decline to nothingness.

What are these, why do passengers need to see them, and why don’t you get them on all lines?

 

[GC class B1]

I’m talking about the barometer-looking things that are set in to the seat housing, near the floor. They seem to climb as the train progresses, only to climb more when the doors open, followed by a rapid decline to nothingness.

What are these, why do passengers need to see them, and why don’t you get them on all lines?

I think they are brake cylinder pressure gauges. They will read zero when the brakes are released and the train is moving. Passengers do not need to act on them.

 

[hexagon789]

I’m talking about the barometer-looking things that are set in to the seat housing, near the floor. They seem to climb as the train progresses, only to climb more when the doors open, followed by a rapid decline to nothingness.

What are these, why do passengers need to see them, and why don’t you get them on all lines?

Air pressure gauges.

I guess one will be main reservoir, one will be brake cylinder. Not sure if Northern Line stock has a brake pipe or if they are pure electric brake control like the Westcode system.

 

[GC class B1]

Air pressure gauges.

I guess one will be main reservoir, one will be brake cylinder. Not sure if Northern Line stock has a brake pipe or if they are pure electric brake control like the Westcode system.

There is only one gauge and I am pretty sure it is brake cylinder pressure.

 

[hexagon789]

There is only one gauge and I am pretty sure it is brake cylinder pressure.

Sorry, the OP said 'gauges' and I've never been on the Northern Line!

 

[Mojo]

why don’t you get them on all lines?

You do; all stock has gauges in the car.

The reason you don't typically see them on Mainline trains is that typically on LU trains fault finding and rectification would be carried out from within the train, typically by lifting the seats or opening cabinets within the cars. Doing things on the outside of the train is obviously less practical within the confines of a tunnel.

 

[Dstock7080]

The gauge will be at 0 while the train is moving, approaching stops/stations it will rise until the rheostatic/regenerative brake kicks in, then drop to 0 until the the friction brake kicks in as the train stops (motor cars only - trailer cars the gauge will react to brake inputs)

 

[AlbertBeale]

Years ago, on older stock at least, it was obvious that the dials related to air pressure in the braking system by the sounds you could hear (and the deceleration you felt) in sync with the pointer on the dial moving. It fascinated me when on the tube as a kid.