Hydraulic Hybrid Fleet Vehicles

How Hydraulic Hybrid Vehicles Work

Hydraulic hybrid systems can capture up to 70% of the kinetic energy that would otherwise be lost during braking. This energy drives a pump, which transfers hydraulic fluid from a low-pressure reservoir to a high-pressure accumulator. When the vehicle accelerates, fluid in the high-pressure accumulator moves to the lower-pressure reservoir, which drives a motor and provides extra torque. This process can improve the vehicle's fuel economy by 25% to 30% compared to its non-hybrid equivalent.

NREL conducts performance evaluations of hydraulic hybrid delivery and refuse vehicles.

Because hydraulic hybrids feature highly efficient regenerative braking systems and "engine off at idle" capabilities, they are ideal for applications where stop-and-go traffic is common.

Learn about NREL's evaluation of hydraulic hybrid fleet vehicles operating in real-world service:


Browse our list of hydraulic hybrid vehicle publications.