DW2/DW3 Acronym

[TheEdge]

Someone out there might know the answer to this.

Class 90s and DVT have a brake isolation valve called a DW3. Does anyone know what it stands for? I've trawled over traction manuals and only ever find it written as DW3, or Westinghouse DW3, never actually defined.

It really annoying me, someone must know!

 

[43096]

Someone out there might know the answer to this.

Class 90s and DVT have a brake isolation valve called a DW3. Does anyone know what it stands for? I've trawled over traction manuals and only ever find it written as DW3, or Westinghouse DW3, never actually defined.

It really annoying me, someone must know!

I’ve never seen it as anything other than DW2/3.

Incidentally it is not “just” a brake isolation valve, it’s a brake pipe pressure control unit - the Westinghouse equivalent of the Davies & Metcalfe E70. On an HST the E70 and DW2 are interchangeable and are critical to brake performance as they propagate the brake from both ends of the train via electrical signals from the driver’s brake controller. It is this (and disc brakes) that allows an HST to operate at 125mph as brake performance is better than a 100mph conventional loco-hauled train.