Other Safety Device

Anti-twoblock Device

The anti-twoblock device prevents damage to the crane that would be caused by pulling the hook block into the boom head. When the hook block approaches the boom head, single top or jib, the anti-twoblock device sends a signal to the load moment indicator, which then stops any further crane action toward the critical condition. When two-blocking is detected, the crane will be set in the following status:

(1)Any operation involving action toward the critical state (hoisting up, extending or lowering the boom) is halted.

(2)If a critical-state operation is attempted, the alarm buzzer sounds and the failure indicator lamp illuminates to alert the operator.

When the crane is automatically stopped because the anti-twoblock device has been activated, retract the boom or hoist down to move the hook block away from the boom head, single top or jib.

◆ The anti-twoblock device for the jib can also be used for the single top.

◆ When the jib or single top is mounted, be sure to connect the leads of the anti-twoblock device correctly. If the leads are not connected, the load moment indicator assumes a two-blocking condition, and all actions toward the critical conditions are automatically stopped.

◆ Once two-blocking has occurred, the alarm buzzer keeps sounding until the hook block is lowered.

Deactivation of the Anti-twoblock Function

Warning

When the anti two block function is deactivated, the stop function will not operate even if the hook block is overhoisted. Be careful not to twoblock the crane when deactivating the anti two block function is unavoidable or specifically required.

Use the anti-twoblock disable switch to deactivate the anti-twoblock function. The anti-twoblock function may hinder stowing the main hook block and mounting or stowing the jib. If this happens, deactivate the function temporarily by pressing the anti-twoblock disable switch. While the switch is held down, the anti-twoblock function is deactivated.