PS097S and PS104S POWER SYSTEMS Machine Systems Caterpillar

Illustration 1	g06130260
HPU300 hydraulic circuit (1) Electric Motor (2) Gear pump (3) Pressure limiting valve (4) Start valve (5) Coupler (6) Hydraulic oil cooler (7) Return filter (8) Breather filter (9) Suction filter (10) Low-pressure bypass valve (11) Hydraulic tank

The HPU300 Hydraulic Power Unit is an electro-hydraulic unit that enables zero-emission working. The electric motor drives a gear pump whose oil flow is sent to a 300.9D Mini Hydraulic Excavator by high-pressure hoses. The main components of the power unit are:

• Electric motor

• Hydraulic components

• Chassis

Depending on the operating state, the oil supply is automatically regulated toward the excavator:

• Start protection - When the HPU is switched on, the oil circulates without pressure for 10 seconds (control via time-lag relay).

• Warmup function - At low temperatures, the oil circulates without pressure until it reaches 5° C (41° F).

• Heat protection - The fan is switched on at an oil temperature of 60° C (140° F) or higher. It is switched off again after the oil cools down to about 45° C (113° F).

• Heat protection - The power unit is stopped at an oil temperature of 95° C (203° F) or higher (protection of hydraulic HPU and excavator components).