| 摘要 |
In one aspect of the present invention, an apparatus for automatically controlling a work element of an earth working machine is disclosed. The work element includes a grapple having a pair of tongs, where the tong pair is controllably actuated by a hydraulic cylinder. An electrohydraulic valve controllably actuates the hydraulic cylinder in response to a command signal. A sensor senses the fluid pressure in the hydraulic cylinder and responsively produces a pressure signal. A controller receives the pressure signal, compares the pressure signal magnitude to a pressure setpoint, and delivers a command signal to the electrohydraulic valve to automatically actuate the tong pair.
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