초록 ▼

A crane is operable in either a regular mode or a heavy duty mode. In the regular mode, an upper works is rotatble, through a turntable bearing, on a lower works. A boom is pivotally connected to one end of the upper works and a counterweight is connected to the opposite end thereof. In the heavy du

A crane is operable in either a regular mode or a heavy duty mode. In the regular mode, an upper works is rotatble, through a turntable bearing, on a lower works. A boom is pivotally connected to one end of the upper works and a counterweight is connected to the opposite end thereof. In the heavy duty mode, a support ring surrounds the lower works and is connected thereto. An auxiliary frame is mounted on the support ring, surrounding the upper works, for rotation on the ring in unison with rotation of the upper works. The boom used in the regular mode is pivotally connected to the auxiliary frame for use as a gantry, and a heavier boom is pivotally connected to the auxiliary frame adjacent the gantry. The counterweight of the machine in the regular mode is shifted to the auxiliary frame opposite the boom and gantry, and an auxiliary counterweight is added to the auxiliary frame.

대표청구항 ▼

In a crane for lifting heavy loads, said crane having a lower works and having an upper works rotatably mounted on the lower works to pivot about an axis, a support track surrounding said lower works and supported from the ground, the improvement comprising a rigid auxiliary frame also pivotal about

In a crane for lifting heavy loads, said crane having a lower works and having an upper works rotatably mounted on the lower works to pivot about an axis, a support track surrounding said lower works and supported from the ground, the improvement comprising a rigid auxiliary frame also pivotal about the axis and supported by the support track only, a boom pivotally mounted on one end of the auxiliary frame and a counterweight mounted on the opposite end of the auxiliary frame, and means connecting said upper works to the frame with vertical play between said connected members for pivoting movement of the frame about the axis with the upper works whereby said frame is mounted on the support track only.