| 摘要 |
<p>PURPOSE:To enable the operation of a construction machine to be performed during its rearward movement in the quite same operational feeling as that of the forward movement by a method wherein hydraulic flow for a steering operation change-over valve and a running operation change-over valve are made in such a direction as opposite to that of the forward movement when an upper turning body is turned to face rearwardly. CONSTITUTION:When the upper turning body is turned by 180 deg., a roller 25 at the extremity end of a spool 24 rides over a cam projection 26. Due to this fact, a flow passage change-over valve 22 is changed-over, a flow of hydraulic oil in each of the circuits 15, 20 is made to be in opposite direction. Thus, an operating direction of a running operation lever 6 and a rotational direction of a running driving hydraulic motor 11, and a turning direction of a steering handle 7 and a moving direction of a steering cylinder 16 are made to be opposite to each other, and even in case of a rearward movement, the operation can be performed in the quite same manner as that found in case of forward movement.</p> |
