Hydraulic circuit for transmissions

A hydraulic circuit for transmissions comprising:

• a hydraulic oil pathway configured to supply hydraulic oil to a hydraulic control part of a transmission, the hydraulic control part hydraulically controlling the transmission;
• a lubricating oil pathway for supplying the oil to a part to be lubricated configured to be lubricated by the oil of the transmission;
• a collecting part configured to collect the oil to be supplied to the hydraulic control part and the part to be lubricated;
• and
• a pump apparatus configured to supply the oil from the collecting part to the hydraulic oil pathway and the lubricating oil pathway,
• wherein the pump apparatus includes:
• a low-pressure oil discharging unit having an air bubble-containing oil discharging part configured to separate an air bubble from the oil sucked from the collecting part and to discharge the oil containing an air bubble to the lubricating oil pathway, and a low-pressure oil discharging part configured to discharge the oil from which an air bubble has been separated;
• and
• a high-pressure oil discharging unit having a high-pressure oil discharging part configured to increase pressure of the oil supplied from the low-pressure oil discharging part of the low-pressure oil discharging unit to have a higher pressure than the oil discharged from the low-pressure oil discharging part, and to discharge the oil to the hydraulic oil pathway.