User's Manual

36 Revision 2 GM550 v1043 FCC-IC.doc
Step 3. Chain length adjustment № 1 – minimum boom angle
i. At minimum boom angle, with no additional weight on the hook block and one part of line
only, lift the boom just enough to have the hook block suspend and clear the sensor chain
and weight.
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. If still
insufficient, contact your service representative.
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 minimum boom angle
Figure: Anti-two-block weight chain length