In order to make the hydraulic excavator complete a certain operation efficiently, sometimes several components in the turntable, boom, stick and bucket need to perform compound action. For example, when the hydraulic excavator is scraping, the boom, stick and bucket need to do compound action. The specific methods are as follows:
Pull the stick valve to make the stick extend out, and stop when it extends beyond the vertical position of the stick. At the same time, operate the bucket valve control handle to make the bucket teeth touch the ground. Gently operate the boom control valve and joystick to raise the boom slightly. At the same time, operate the control handle of the stick valve to recover the stick. During the recovery of the stick, the bucket can scrape the ground in the horizontal direction. Once the stick is moved to the vertical position, operate the boom control valve and joystick to lower the boom slightly. Through the above compound actions of boom, stick and bucket, the ground scraping operation can be basically completed.
When pushing the boom control valve and the joystick, because the stroke of the boom control valve spool is short and its action is sensitive, slightly pushing the control valve can make the boom cylinder have rod cavity throttling and oil return. Compared with the control valve, the stroke of the control valve spool is longer, so the time for the boom control valve to replenish oil to the rodless cavity of the boom cylinder lags slightly. With this setting mode, the boom cylinder can work smoothly.
