Pump 1B is powered by AC
bus 2 and Pump 2B by AC
bus 1. I would guess it is more to do with electrical load shedding with an engine out rather than evening out hydraulic systems.
It makes sense that the electrically driven hyd pump is powered by the opposite engines IDG, so that an engine failure would not potentially take out all that sides hydraulic pressure.
Is it not the case that if you switch either pump 1B or 2B to ON
it will run regardless of whether an engine has failed. It is only in the AUTO position that the pump won't run.
Hydraulic pressure will be the same with one pump or two. However, the maximum flow available will be reduced with only one pump.
[Edited 2007-11-01 15:29:01]
The glass isn't half empty, or half full, it's twice as big as it needs to be.