New Underground Stock at Derby

[t o m]

I've just seen some new Underground stock off Platform 6 at Derby. There were two class 20 locos at each end and also a barrier wagon at each end. Why does it need four locos and what is the purpose of the barrier wagons?

 

[Mugby]

Well the barrier wagons are simply to provide a compatible coupling between the locos and the stock and the two locos at each end are presumably to avoid any need to run round. I would agree though that 4000hp seems a bit excessive for a stock movement!

 

[asylumxl]

Well the barrier wagons are simply to provide a compatible coupling between the locos and the stock and the two locos at each end are presumably to avoid any need to run round. I would agree though that 4000hp seems a bit excessive for a stock movement!

And adequate brake force.

 

[AlexS]

Are they clever translator wagons in that they convert the train brake into a type that will work with the Underground train or are they simply for coupling purposes with the train being through piped, is the question really!

The 20s either end are I think for reversal purposes to save running around. I believe the train has slipped to a stand on the Coalville line before so a pair seem to be required.

 

[asylumxl]

Are they clever translator wagons in that they convert the train brake into a type that will work with the Underground train or are they simply for coupling purposes with the train being through piped, is the question really!

The 20s either end are I think for reversal purposes to save running around. I believe the train has slipped to a stand on the Coalville line before so a pair seem to be required.

Usually the train is piped through I believe.

 

[mainframe444]

I've just seen some new Underground stock off Platform 6 at Derby. There were two class 20 locos at each end and also a barrier wagon at each end. Why does it need four locos and what is the purpose of the barrier wagons?

The underground stock is hauled as a "swinger", i.e. there are no working brakes on it when towed.

The barrier wagons serve two purposes, translators to enable the stock to be coupled up (one end fitted with an LU coupler), and additional brake force.

The reason for two locos at each end is to avoid running round the train as there are a number of reversals during the journey.

There is a brake pipe running the length of the undergound train to control the brakes on the rear locos/barrier wagon from the front ones.

The class 20s are also fitted with tripcocks for running on LU tracks, in order for these to be fitted the sand boxes were removed, hence the occasional adhesion problems in the Coalville area.

MainFrame

 

[Dstock7080]

4x 20s are also used to comply with loading/axle weight restrictions on LU infrastructure.