Hydraulically driven type working machine

A hydraulically driven type working machine comprising:

• a boom driving hydraulic cylinder, an arm driving hydraulic cylinder and a working tool driving hydraulic cylinder are formed as hydraulic cylinders respectively having communication passages supplying and discharging a working oil fluid from inner portions of respective piston rods to head side oil chambers and bottom side oil chambers in piston chambers within respective cylinders, respective cylinders sides of the driving hydraulic cylinders are respectively connected to the boom, the arm and the working tool side so as to form longitudinally moving bodies, and respective piston rod sides are respectively arranged so as to form hoist supporting points by supporting shaft pins via supporting brackets provided in the machine frame, the boom and the arm side,
• wherein said hydraulically driven type working machine is provided with a first swivel joint mechanism mounting a boom built-in pipe arrangement to a cylindrical joint and connected to the boom so that the cylindrical joint rotates together with a swing motion of said boom, a third swivel joint mechanism connecting a cylindrical joint to said boom side so as to form a connection joint of a boom built-in pipe arrangement and setting a pipe arrangement block and a columnar joint integrally mounted to said arm side to a connection joint of an arm built-in pipe arrangement, and a second swivel joint mechanism connecting a cylindrical joint to said machine frame side so as to form a connection joint of a machine frame side pipe arrangement and setting a pipe arrangement block and a columnar joint to a connection joint of a boom driving hydraulic cylinder side pipe arrangement,
• in the hydraulic pipe arrangement to said arm driving hydraulic cylinder, the boom built-in pipe arrangement extending via the first swivel joint mechanism is connected to a front end portion of the piston rod in the arm driving hydraulic cylinder,
• in the hydraulic pipe arrangement to said working tool driving hydraulic cylinder, the arm built-in pipe arrangement extending via the third swivel joint mechanism is connected to a front end portion of the piston rod in the working tool hydraulic cylinder, and
• in the hydraulic pipe arrangement to said boom driving hydraulic cylinder, the pipe arrangement block and the columnar joint of the second swivel joint mechanism are integrally connected to the piston rod of the boom driving hydraulic cylinder, whereby the respective hydraulic pipe arrangement to the driving hydraulic cylinders are not exposed to an external portion.