Straight Answer First
If you searched for a "Doosan crane hydraulic pump," here's the honest answer: Doosan (now largely rebranded to Develon for its construction equipment business) focuses on excavators, wheel loaders, articulated trucks, and crawler dozers — cranes aren't part of this current product range. We'd rather tell you this directly than pad out a page pretending otherwise.
Doosan's construction equipment strength is in earthmoving — excavators (DX-series, covered on our Doosan Excavator page) and, more recently under the Develon name, crawler dozers (DD-series, covered on our Doosan Bulldozer page). If you're looking for a Doosan-branded crane and haven't found one, that's because it isn't part of the current lineup.