| 摘要 |
A twin-section boom is pivotally attached to the front of an excavator frame, and a saddle block pivotally mounted approximately half-way up the length of the boom slidably retains a dipper handle that moves back and forth between the boom sections. A pinion gear located in the saddle block and driven by a hydraulic motor engages a rack gear on the underside of the handle to provide a crowd-retract motion. A dipper is rotatably attached at the forward end of the handle to prevent transmission of torsional forces along the handle, and the dipper is retained in an upright attitude by twin dual hoist ropes extending over boom point sheaves attached at the upper ends of the boom sections.
|
