| 摘要 |
A counterbalanced crane structure having an upright boom and diverging staymast mounted to a ground supported mobile crane base. An independent mobile counterweight unit has a vertical counterweight strut connected to the outer end of the staymast. The counterweight unit is interconnected with the crane base by an elongated horizontal stinger assembly. The counterweight unit is powered to move in an arc, the center of which is determined by the crane base. Turning motion is transmitted from the moving counterweight unit to the main boom and staymast by the stinger. Movable connections on the stinger permit pivotal movement of the counterweight unit about an axis that is substantially radial with the center turning axis of the mainboom and staymast and another pivot axis that is transverse to the radial axis. Limited movement of the counterweight unit toward or away from the crane base is permitted to eliminate direct transfer of tension and compressive stresses through the stinger. The counterweight strut directly transmits tension and compressive forces between the outer end of the staymast and the ground supported counterweight unit. It operates as a mast stop, supporting the staymast against sudden recoil when a sudden shifting of a load occurs along the main boom. Additionally, the counterweight strut facilitates erection of the crane assembly.
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