HYBRID SYSTEM AND WORKING MACHINE INCLUDING HYBRID SYSTEM

A hybrid system (25) includes an engine (7), a generator (9) to be driven by the engine (7), an electric actuator (26) to be driven by electricity generated by the generator (9), a transmission mechanism (27) to transmit power from the engine (7), a hydraulic pump (17) to receive power from the engine (7) through the transmission mechanism (27) to deliver hydraulic fluid, and a hydraulic actuator (28) to be driven by hydraulic fluid delivered by the hydraulic pump (17). The transmission mechanism (27) includes a first transmission path (39) to transmit power from the engine (7) to the hydraulic pump (17) when a rotational speed of the engine (7) is a first rotational speed (R1), and a second transmission path (40) to transmit power from the engine (7) to the hydraulic pump (17) at a speed change ratio at which rotational speed is increased to a greater degree than the first transmission path (39) when the rotational speed of the engine (7) is a second rotational speed (R2) lower than the first rotational speed (R1).