The engine is liquid cooled.
The OP was responding to a question about a water cooled heat exchanger for the hydraulic oil. And he is saying that is air cooled.
Like some cars/trucks have an air cooler for the transmission....where ONLY trans oil is running through them. And some have the cooler immersed in the radiator.
Tractors (usually on larger ones) can have a hydraulic cooler than cools of the engine antifreeze....which is a potential source for water in the oil. That was the purpose of the question. But has been ruled out by the OP as only having an air cooler for the hydraulics
