Hydraulic system for providing auxiliary drive to a powertrain and a hydraulic circuit

This disclosure is directed towards a hydraulic system for providing auxiliary drive to a powertrain (11) and a hydraulic circuit (12) by storing and releasing hydraulic fluid using an accumulator (29). A hydraulic drive system (10) comprises an engine (14), a hydraulic machine (22) operably connected to the engine (14), a pump (17), an accumulator (29) and at least one valve (20, 27). The pump (17) is driven by the engine (14) and is configured to control a hydraulic circuit (12). The accumulator (29) is fluidly connected to the hydraulic circuit (21) and the hydraulic machine (22). In one instance, the at least one valve (20, 27) is operable to direct pressurised fluid from at least one of the hydraulic machine (22) and the pump (17) to charge the accumulator (29). Alternatively, the at least one valve (20, 27) is operable to direct pressurised fluid from the accumulator (29) to at least one of the hydraulic machine (22) and the hydraulic circuit (21).