Hydraulic Power Units deliver an Oil Flow at a certain Pressure,
From a 12 Volt DC 0.8 kW unit delivering 5 Liters per minute at a pressure of 1,500 psi,
to 100 Litres per minute at a pressure of 4,500 psi requiring an 80 kW diesel Engine.

The final design of the hydraulic Power Unit will depend: on your specific requirements, including the desired oil flow rate, operating pressure, application type, and installation location.

For example 12 and 24 Volt DC for smaller Mobile applications,
240 and 415 Volt AC for Stationary Applications
and Petrol or Diesel Engines for Larger Mobile or Remote applications.

The important rule of hydraulics for a known fixed available Horsepower is as follows,
If you want more Pressure: you must reduce flow and install a smaller pump.
If you want more Flow: you must Reduce Pressure and install a Larger pump.
If you want Both: i.e. More Flow and More Pressure you need more POWER !