US Patent 11346082 Fluid pressure drive device

A hydraulic drive device according to an embodiment includes a main pump and a single pressure gauge. The main pump controls discharge flow rates of a first hydraulic oil and a second hydraulic oil discharged into two or more first pressure oil supply passage and second pressure oil supply passage with a single swash plate. The main pump is a swash plate variable displacement type split flow hydraulic pump. The pressure gauge measures an intermediate pressure of the discharged fluid at a merging point between the first pressure oil supply passage and the second pressure oil supply passage. The discharge flow passage is controlled based on a pressure value obtained by the pressure gauge.