User's Manual

GM550 v1043 FCC-IC.doc Revision 2 37
Step 4. Chain length adjustment № 2 – maximum boom angle
i. Raise the boom to the maximum angle.
ii. Hoist slowly until the red two-block warning lights comes on and the buzzer sounds. Note
the hoisting distance remaining; this distance must be great enough to allow the operator
and the lockout system, if installed, to prevent a two-block event. If necessary, add
lightweight chain between the sensor and weight to increase warning distance. Verify that
the warning distance is equal to or greater than that determined at the minimum boom
angle.
Tip: Have a second person stand off to the side of the crane to closely monitor the hoisting
distance from the hook block to the head sheave block.
Step 5. Chain length adjustment № 3 – speed test: Lower the boom until the weight height
becomes visually clear to the operator. Repeatedly create two-block, progressively
hoisting faster, to ensure that the warning and lockout work within acceptable amount
of time and distance. Increase the length of the small chain if needed.
A) Anti-two-block
switch triggers
two-block alarm
B) Hook block stops rising,
two-block prevented with
safety margin
Figure: Anti-two-block weight chain length test at maximum boom angle