The noise in the main gear on an A320

Several legs with Airbus on the last trip and during push back and taxi the noise similar to a “barking dog” occurred in the area of the main gear. It was much more pronounced in the newer A320 operated by Virgin America than the older Cactus one.

I suspect it’s a hydraulic pump of some kind and I’m curious if I’m correct and if so, what the hell kind of design is that?

That is actually just the co-pilot.

Yes, it is a hydraulic pump that equalizes pressure between the different hydraulic system of the aircraft (I believe they’re called "red’ and “green”).

Woof !

en.wikipedia.org/wiki/Power_transfer_unit