User's Manual

18 LS420 Universal User Manual V2.91 2003-01-21.doc

Step 3) Test chain length.

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 up and the buzzer sounds. Note the

hoisting distance remaining; this distance must be great enough to allow the operator or 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.

iii) Raise the boom to the maximum angle and repeat the procedure detailed in Step 2 very

carefully. It will help to have a second person standing off to the side of the crane to closely

monitor the hoisting distance from the hook block to the head sheave block. Verify that the

warning distance is equal to or greater than that determined at the minimum boom angle.

iv) Lower the boom until the weight height becomes visually clear to the operator. Repeat-

edly create two-block, progressively hoisting faster to ensure that the warning and lockout (if

installed) work within acceptable amount of time and distance. Increase the length of the

small chain if needed.

Boom at

minimum

angle, two-

block alarm

triggered.

Hook block stops

rising, two-block

prevented with

safety margin.