What is Overcharge?

[doningtonphil]

Hello

I think I know what Overcharge is used for.
The reason I only think I know is that there seen to be numerous ideas of what it is used for, and when it is used.

So, if you are a driver, can you add details here of WHY you have been advised you should use, along with WHEN it should be used.

If you can include any additional about its use - timings etc - I would much appreciate it.

Many thanks

Phil

 

[dooton]

An overcharge inflates the brake pipe up to around 5.4 bar, to fully release the brakes. This prevents dragging brakes. You can get subtle changes in pressure with different brake pipe controllers, so this process resets/equalises the brakes on all vehicles.

Only used on trains with brake pipe control.
The brake distributors naturally bleed off air to maintain sensitivity so when an overcharge is carried out, it bleeds off over 4-6 minutes and the brake pipe will settle at 5 bar.

At my TOC (passenger loco hauled) overcharge every time ends changed and when mobilising the train.

 

[Unobrow]

An overcharge inflates the brake pipe up to around 5.4 bar, to fully release the brakes. This prevents dragging brakes. You can get subtle changes in pressure with different brake pipe controllers, so this process resets/equalises the brakes on all vehicles.

Only used on trains with brake pipe control.
The brake distributors naturally bleed off air to maintain sensitivity so when an overcharge is carried out, it bleeds off over 4-6 minutes and the brake pipe will settle at 5 bar.

At my TOC (passenger loco hauled) overcharge every time ends changed and when mobilising the train.

On freight trains it’s used after a brake test to settle all the distributors at an even pressure/setting for brake applications once the excess has bled off. It would also avoid dragging brakes. Should also only be done whilst at a stand. No brake application should be made until the excess pressure has bled off or the brakes will go back to 5.4 once released and start to bleed off again. There’s a risk if done on the move that the bounce of the wagons can upset the distributors whilst the excess is bleeding off and they won’t all settle back down evenly, and then risking uneven brake applications and dragging brakes.

 

[Sheridan]

On freight trains it’s used after a brake test to settle all the distributors at an even pressure/setting for brake applications once the excess has bled off. It would also avoid dragging brakes. Should also only be done whilst at a stand. No brake application should be made until the excess pressure has bled off or the brakes will go back to 5.4 once released and start to bleed off again. There’s a risk if done on the move that the bounce of the wagons can upset the distributors whilst the excess is bleeding off and they won’t all settle back down evenly, and then risking uneven brake applications and dragging brakes.

On passenger trains it can be done on the move. It’s best not to do it approaching an area where you’re expecting to stop, as the higher pressure in the pipe means that you can’t achieve the small brake applications you would usually use to bring a passenger service to a stand once down at lower speeds. It can take 5-10 minutes for the extra pressure to bleed off.