What are the three main components of a hydraulic power unit?

Here are the three non-negotiable components of every hydraulic power unit (HPU), distilled from hands-on experience:

1. Prime Mover (Energy Input)
Purpose: Drives the hydraulic pump.
Types:
Electric Motor: AC/DC motors for factories/fixed equipment. Voltage must match local power grid.
Internal Combustion Engine: Diesel/gasoline engines for mobile/marine/remote sites.
Critical Spec: Torque output at startup must overcome pump breakaway friction.

2. Hydraulic Pump (Energy Converter)
Purpose: Draws fluid from tank, pressurizes it, and forces it into the system.
Types:
Gear Pumps: Affordable, compact. Used for basic systems (<250 bar).
Piston Pumps: High-pressure (500+ bar), efficient for precision controls.
Vane Pumps: Mid-range pressure, quieter operation.
Killer Mistake: Running the pump dry – destroys seals in seconds.

3. Reservoir (Fluid & Thermal Management)
Purpose: Stores hydraulic fluid, dissipates heat, settles contaminants.
Key Features:
Baffle Plate: Prevents fluid sloshing, separates air from oil.
Air Breather: Prevents vacuum during pump suction while blocking dirt.
Suction/Return Zones: Isolate dirty return oil from pump inlet.
Material: Steel for durability, aluminum for weight-sensitive apps.