Work machine

A work machine comprising:

• an undercarriage provided with a travel device;
• an upperstructure pivotally attached to the undercarriage;
• a closed circuit provided with at least one closed-circuit hydraulic pump having two outlet/inlet ports each enabling the outlet and inlet of hydraulic fluid in both directions and a single-rod cylinder having a piston, a cap-end chamber into which the hydraulic fluid is introduced when the piston extends, and a rod-end chamber into which the hydraulic fluid is introduced when the piston retracts, the two outlet/inlet ports of the closed-circuit hydraulic pump being annularly connected with the cap-end chamber and the rod-end chamber;
• an open circuit provided with an open-circuit hydraulic pump having an inlet port into which hydraulic fluid flows from a reservoir, and an outlet port from which hydraulic fluid flows out;
• a connection circuit which introduces the hydraulic fluid flowing out from the open-circuit hydraulic pump into the closed circuit;
• an engine;
• and
• a power transmission device that includes four rotational shafts and transmits a rotational power of the engine to the closed-circuit hydraulic pump and the open-circuit hydraulic pump;
• wherein
• the reservoir is mounted on a frame supporting the upperstructure;
• the engine is mounted on the frame adjacent to the reservoir;
• the closed-circuit hydraulic pump is connected to the two upper rotational shafts among the four rotational shafts;
• and
• the open-circuit hydraulic pump is connected to the two lower rotational shafts among the four rotational shafts.