225 powered by 2 x Class 91s

[TGV]

I never think of HSTs or Eurostars (or any TGV) as a multiple unit. They are not locos either. They fall into a category of their own: "power cars". In other words, a pair of non-passenger-carrying driving vehicles used to provide tractive effort and hotel power to each end of a fixed formation of specfic carriages.

To me a multiple unit is a self-contained train which is designed to be regularly used in service either on it's own or coupled to one or more others of the same or compatible class to provide more flexibility in capacity. None of that applies to HST or Eurostar which do not have the formation altered during service.

But the dual 91 thing will still never happen.

 

[gimmea50anyday]

I think that I remember reading that a class 37 has been turned out on at least one occasion to provide the necessary assistance, which in terms of power output seems to rather defy the point (Assuming that the entire HST formation would be being hauled "dead" as would be usual when an HST is being hauled).

Where a loco has been provided to assist an ailing hst, the power car still able to provide traction would work in conjunction with the rescue locomotive, I recall Colin marsden 's book diesels on the western region there is an image of brand new 58001 rescuing a hst which had failed. The 58 subsequently failed and itself was pushed into Exeter by the remaining power car along with its train set!

 

[O L Leigh]

Where a loco has been provided to assist an ailing hst, the power car still able to provide traction would work in conjunction with the rescue locomotive, I recall Colin marsden 's book diesels on the western region there is an image of brand new 58001 rescuing a hst which had failed. The 58 subsequently failed and itself was pushed into Exeter by the remaining power car along with its train set!

A slight misunderstanding. The assisting loco cannot work in multiple with the HST, and nor would this be normal. The event referred to was simply a way of digging themselves out of a hole.

O L Leigh

 

[GM078]

When the 43s were used with the 91s were they actually hauling the train, or merely acting as a DVT? Would the 91 have been dead?

 

[D365]

When the 43s were used with the 91s were they actually hauling the train, or merely acting as a DVT? Would the 91 have been dead?

Initially the DVT's power unit was only used to supply ETS for the Mk3 coaches, as they differed from the Mk4's, and hence the engines were only running at approx 1000 rpm, just above idling. However, prolonged use of the power cars in this way lead to an excessive build up of un-burnt fuel in the silencers and this eventually lead to fires. It was decided that the PC engines should be powered up as normal and this then meant that the test trains had a combined available power of over 7000 HP. A modification to the TDM control arrangements allowed the engine to be controlled from the class 91 and an increase in speed up to the maximum of 125 mile/h was accomplished with ease!

http://www.traintesting.com/ic225_2.htm