Unknown Gauge On Jubilee

Does anyone know what the lower gauge shows? It doesn't seem to move in game, but nevertheless I'm curious. The unit suggests it indicates pressure.

 

It looks like it’s for the steam heating for the carriages.

 

Yes I would also say the steam heat for coaches.

 

But the units, lbs/square inch, would indicate a pressure gauge of some kind.

 

Yes, it’s the pressure of the steam going to the carriages.

 

Thank you for help. It may be that as 8F doesn't have it nor steam heating.

 

The 8F wouldn't because it was built for freight.