Construction machine

Abstract

A control valve (23) for travel is provided in a lower traveling structure (15) to control the flow of operating oil to be delivered to a hydraulic motor (20) for travel from a hydraulic pump (10). An operating oil tank (12) and the hydraulic motor (20) for travel is connected by a hydraulic pipe (25). The hydraulic pipe (25) is configured of a supply low-pressure pipe part (25A), a pump-side high-pressure pipe part (25B) and a valve-side high-pressure pipe part (25C) for connection between the operating oil tank (12), the hydraulic pump (10) and the control valve (23) for travel, switching high-pressure pipe parts (25D, 25E) that are provided in the lower traveling structure (15) for connection between the control valve (23) for travel motor and the hydraulic motor (20) for travel, and a valve-side low-pressure pipe part (25F) and a tank-side low-pressure pipe part (25G) that are provided across from the lower traveling structure (15) to the upper revolving structure (3) to establish connection between the control valve (23) for travel motor and the operating oil tank (12).

1 . A construction machine comprising:
 an automotive lower traveling structure by a hydraulic motor for travel; and   an upper revolving structure mounted via a revolving device on the lower traveling structure to be capable of revolving thereto,   the upper revolving structure including:   a prime mover;   an operating oil tank; and   a hydraulic pump that is driven by the prime mover to deliver operating oil stored in the operating oil tank, characterized by including:   a control valve for travel motor provided in the lower traveling structure to control the flow of the operating oil that is delivered from the hydraulic pump to the hydraulic motor for travel; and   a hydraulic pipe that establishes connection between the operating oil tank and the hydraulic motor for travel, wherein the hydraulic pipe includes:   a supply pipe part that establishes connection between the operating oil tank, the hydraulic pump and the control valve for travel motor for supply of the operating oil;   a high-pressure pipe part that is provided in the lower traveling structure to establish connection between the control valve for travel motor and the hydraulic motor for travel and in which high-pressure operating oil that is delivered from the hydraulic pump and is supplied to the hydraulic motor for travel flows; and   a low-pressure pipe part that is provided across from the lower traveling structure to the upper revolving structure to establish connection between the control valve for travel motor and the operating oil tank and in which low-pressure operating oil that is discharged from the hydraulic motor for travel and is returned back from the control valve for travel motor to the operating oil tank flows.   
     
     
         2 . The construction machine according to  claim 1 ,
 wherein the lower traveling structure includes:   a truck frame including a center frame and side frames extending in the front-back direction on both of the left and right sides of the center frame;   a driving wheel that is provided on the rear part of the side frame and is rotated by the hydraulic motor for travel;   an idler wheel that is provided on the front part of the side frame; and   a crawler track that is wound around between the driving wheel and the idler wheel, wherein   the center frame is provided with a valve attaching surface on the rear surface facing the hydraulic motor for travel in the front-back direction, and   the control valve for travel motor is attached on the valve attaching surface of the center frame.   
     
     
         3 . The construction machine according to  claim 2 , further comprising:
 a center joint provided in a revolving center position of the revolving device to cause the operating oil to flow between the lower traveling structure and the upper revolving structure wherein   the low-pressure pipe part is provided via the center joint across between the upper revolving structure and the lower traveling structure, and   the low-pressure pipe part is provided with a valve-side low-pressure pipe part between the center joint and the control valve for travel motor, the valve-side low-pressure pipe part being arranged through a position more separate from the crawler track than the high-pressure pipe part.   
     
     
         4 . The construction machine according to  claim 1 ,
 wherein   the control valve for travel motor comprises a plurality of control valves that are provided in positions lining up in the left-right direction and in positions shifting to each other in the upper-lower direction.