Central line trains losing power/braking suddenly for seemingly no obvious reason

[Sweetjesus]

I started to use Central line more often and most of times, it works flawlessly.

But sometimes, whenever I get on the train, and the train starts to accelerate exiting the station, and it suddenly brakes/loses power for a second then accelerates and then brakes/loses power again. This is repeated twice or thrice before it starts to accelerate fully to next station.

One time I did see a central line train pulling into a station and it just stops halfway into the station, it then starts to move slowly to the front end of the station.

I was wondering if there was a specific explanation for what I'm seeing? So far, Central line is the only line I've seen this to happen.

 

[BJames]

This does seem to happen a lot on the central line more than other lines.

I have a vague memory, I'm sure someone will be along to correct if I'm wrong, that this has something to do with someone leaning heavily on the doors impacting the sensitive edge? A driver said something along the lines of this over the PA once as it was happening after most stops.

 

[Mojo]

But sometimes, whenever I get on the train, and the train starts to accelerate exiting the station, and it suddenly brakes/loses power for a second then accelerates and then brakes/loses power again. This is repeated twice or thrice before it starts to accelerate fully to next station.

In this instance it is probably caused by customers leaning or pulling on the doors, which then open (within tolerance as one of the leafs within double doors has a “pushback” feature designed to allow people to remove anything trapped) causing the train to lose its interlock. The train doesn’t brake, but the motors would cut out.

One time I did see a central line train pulling into a station and it just stops halfway into the station, it then starts to move slowly to the front end of the station.

A separate issue, most likely caused by the train losing codes probably due to wheel slip or slide. The Train Operator would then switch the train into one of the manual modes and berth the train.

I have a vague memory, I'm sure someone will be along to correct if I'm wrong, that this has something to do with someone leaning heavily on the doors impacting the sensitive edge?

You don’t even have to be leaning on them heavily, if you have the palms of your hands or maybe the sole of your shoe on the door that can be pushed open on the springs it will open with the normal acceleration of the train. 92 stock doesn’t have Sensitive Edge, this is on 09/S stock and exists because those stocks don’t have pushback springs.

 

[BJames]

Ah right, makes sense!

 

[rebmcr]

I always thought the advice to "not lean on the doors" is misleading, as it seems to imply that the outward force (towards the tunnel wall) is the problematic aspect.

Instead the wording to "not brace against the doors when the train speeds up or slows down" might be more widely understood.

 

[Sweetjesus]

Ahhh that's my curiosity satisfied, thanks for the replies!