Class 91 hauling HST stock

[dubscottie]

Why were the HST coaches fitted with a "non standard" ETH system in the first place?

Simplicity... The A/C needs a 3-phase 415v supply and the Powercars supplied this anyway. No need to carry around heavy M/A sets.

On loco-hauled stock a Motor Alternator set is needed to convert the 800-1000v supply to 415v 3-phase for the A/C units.

For a 91 to power HST stock each coach would need a M/A set to be fitted (although i think Mk4's use some sort of rectifier instead of a M/A set.. Cant remember)

 

[E&W Lucas]

Someone posted an article about this, but suggested a single diesel locomotive was to be used north of Edinburgh

I received the full Press Release from East Coast this morning and it makes more sense now

The proposal is to have flexibility between a Class 91 and HST power car, between both train types
This suggests converting all the HST coaches to standard ETH system first
It would then be possible to remove (or leave the DVT in formation) and use either a Class 91, single HST Power car (thunderbird recovery), or pair of HST Power cars (in lieu of Class 91)
This would then allow much more flexibility
A single HST Power car could be used on short sections under the wires (out and back)
Equally, pairs of HST Power cars could be paired up and used in effect as a single loco (such as north of Edinburgh)

Following on from that is the retention of the Class 91 Mark 4 coaches, if IEP proceeds
In order to increase reliability the sets would have the DVT removed and HST power car utilised

However, this appears to be at just the development stage and a decision is not likely for at least five or six years

Management- it's not about what you actually do, but what you are seen to do.