Difference between Class 25/2 and Class 25/3

[MattR]

This is a question the Internet can't seem to give me an answer for.

 

There is a difference between the 25/2s and 25/3s fuel/water tanks (I'm not sure what they're technically called) on the underframe between the bogies.

 

It is obvious on the 25/1s and the 25/2s that there are two of them, completely filling this space between the bogies.

 

However, the 25/3s only appear to have one -- on the No. 1 side (fan side) of the locomotive. On the No. 2 side, it's just a large empty space.

 

Everything I've been able to find claims that all the differences between the 25/2 and 25/3 were internal only and outwardly looked exactly the same, but this fuel/water tank issue seems to me a huge difference.

 

What are these tanks and what was the story behind why the 25/3 only has one?

 

Thanks!

 

 

 

Edited December 21, 2022 by MattR

[Mark Forrest]

The larger tank is the fuel tank, the smaller is the water tank.  The water tank was fitted to locos with a steam heating boiler.

Only a few 25/2 with the revised style of body had boilers (and therefore water tanks) these were D5233 - D5237. No 25/3 had boilers so they didn't need water tanks.

 

[MattR]

That explains it! Thank you!

[stovepipe]

The 25/3 were built with the boiler room ventilation grilles, depsite not having boilers. These were usually covered over with a plate, but around the late 1970s a number had the grilles replaced with sheet metal let into the bodysides, like this at no.2 end.