London Underground Train Dials Under Seat In Front Of Me
Discussion
Hello,
On the tube this morning I noticed there were two dials under the seat in front of me. They resembled air pressure dials (technical term).
It was very nice to be able to watch them move about, but I have no idea what they relate to, or why as a passenger I should be offered such information. To be honest a clock or temperature gauge would be more useful for the daily commute.
Any idea what I'm referring to, and how can I interpret such data?
Thanks.
On the tube this morning I noticed there were two dials under the seat in front of me. They resembled air pressure dials (technical term).
It was very nice to be able to watch them move about, but I have no idea what they relate to, or why as a passenger I should be offered such information. To be honest a clock or temperature gauge would be more useful for the daily commute.
Any idea what I'm referring to, and how can I interpret such data?
Thanks.
Vacuum reserve for the brakes. Dad used to work at Acton Depot and I once asked the very same question, they are there because under that seat will be the vacuum tanks and it's convenient to have the gauge visible without lifting the seat.
p.s. Also if you look up at the bar where the adverts are you often see what look like random letters or groups of letters & symbols, these tell the engineer what equipment is under the adjcent seat.
p.s. Also if you look up at the bar where the adverts are you often see what look like random letters or groups of letters & symbols, these tell the engineer what equipment is under the adjcent seat.
Edited by RichB on Tuesday 19th April 17:07
Brake cylinder pressure guages. At zero when the brake is off, and up to a max of @ 50psi when it is on.
They are in the passenger compartment to allow the driver to refer to them in case of a brake defect, or dragging brake (air trapped in the cylinder).
On normal trains they are outside underneath, not much good on a tube train as you could never see them in the tunnels!
They are in the passenger compartment to allow the driver to refer to them in case of a brake defect, or dragging brake (air trapped in the cylinder).
On normal trains they are outside underneath, not much good on a tube train as you could never see them in the tunnels!
neilb62 said:
Brake cylinder pressure guages. At zero when the brake is off, and up to a max of @ 50psi when it is on.
They are in the passenger compartment to allow the driver to refer to them in case of a brake defect, or dragging brake (air trapped in the cylinder).
On normal trains they are outside underneath, not much good on a tube train as you could never see them in the tunnels!
I always thought it was the other way round? i.e. no pressure brakes on (in case of leak (fail safe)), and pressure to relase the brakes? They are in the passenger compartment to allow the driver to refer to them in case of a brake defect, or dragging brake (air trapped in the cylinder).
On normal trains they are outside underneath, not much good on a tube train as you could never see them in the tunnels!
Thanks all! Regarding pictures I figured leaning down and taking pictures through the legs of the bloke opposite me was not recommended on the morning commute. The Evening commute, however...!
This makes sense: "On normal trains they are outside underneath, not much good on a tube train as you could never see them in the tunnels!"
This makes sense: "On normal trains they are outside underneath, not much good on a tube train as you could never see them in the tunnels!"
Brother D said:
I always thought it was the other way round? i.e. no pressure brakes on (in case of leak (fail safe)), and pressure to relase the brakes?
The pressure is created in the train brake pipe (5 bar) to keep the brakes released, any reduction in this pressure, either from the drivers brake valve (controlled) or train division, burst, communication cord etc (uncontrolled) will apply the brakes. This gauge would only be in the drivers cab, there being no need for it in every coach. Most modern trains no longer use this system, instead they apply the brake electrically via a brake control unit so only the brake cylinder gauge will be seen.The brake control units are wired in a loop around the train so any break in the circuit will result in an emergency brake application, thus keeping the fail safe element.
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