Engine-driven pump.
Produces 3,000 psi and is used to operate the hydraulic system components. These pumps are the primary produces of hydraulic fluid volume, since they can can supply six times more volume than the electric motor-driven pump - this means the EDP can move components on the hydraulic system at a faster rate than the EMDP.
When the pumps are selected OFF on the overhead panel, the corresponding blocking valve is energised. This means that the pump will continue to operate, but fluid will be blocked from moving on the pump supply line.
The pump itself is cooled by hydraulic fluid flowing through the pump. This remains true even when the blocking valve is energised, as fluid will move through the pump and back to the reservoir.
Used along with the EMDP to pressurise hydraulic fluid up to 3,000 psi.