HST operation.

[nozzacook]

Just found this video on YouTube. My question is can Hst's work in multiple or will the driver only have power control of the front pair, and if that is the case can the front pair provide electrical power to the train.

http://youtu.be/QDS6DNtVWSk

[tubeguru]

You could ask the only forum member who drives HSTs for a job ...

[The Raven]

If HS2 opens what will Tubeguru drive be renamed to?
MST (Medium Speed Train)?

[tubeguru]

If HS2 opens what will Tubeguru drive be renamed to?
MST (Medium Speed Train)?

I don't think I will sign the new trains as a Plymouth driver. I think we'll retain HSTs for West of England services.

As to Nozza's question about HSTs coupling, the move that you saw in that video was necessary because of the lack of locos on today's railway. The HST in question had failed, and in the absence of a loco to rescue it, back-to-back power cars were sent out instead.

The rear-facing power car of the front two was coupled to the leading power car of the train by means of the "long coupling bar". All HST power cars have two coupling bars in a cupboard. There is a "short" one and "long" one. The short bar is for coupling the power car to a loco, and here is a picture of a power car with the short bar attached:

http://www.lococarriage.org.uk/St%20Phi ... 20HSTs.jpg

The long bar is used to couple two power cars together. When power cars are coupled in this way, the only connections that can exist between the two are the main reservoir and brake pipes, so that the train has a continuous brake throughout. If you were to not couple up the main res and brake pipe, the only braking force available would be on the two back-to-back power cars.

On a normal HST, the electrical connections along the train are conveyed via the "36-way jumper". This means that any action taking place in the front power car, such as taking power or braking, is sent to the rear one. If the cable is disconnected at any point, then continuity is lost.

As for "electrical power", I assume you're referring to what we call "train supply". TS is usually supplied from the rear power car when the train is running. Assuming that the rear power car's engine is running, the TS would be supplied from there. If that failed HST had only the front engine running, then the TS would be provided from that one.

As there is no 36-way jumper connection possible between the back-to-back power cars to the main HST, the only thing the back-to-back power cars have control over is the application of the brake. Hopefully, all that makes sense.

[tubeguru]

So in answer to your question - no, full HSTs cannot be coupled in multiple, but two power cars CAN be, back-to-back as in the video.

[nozzacook]

Cheers for that.