MAINTENANCE 999 LUFFING JIB OPERATOR MANUAL
6-6
Published 05-15-17, Control # 043-09
AUTOMATIC BOOM STOP ADJUSTMENT
Maximum Boom Angle
Boom stop limit switch assembly (5, Figure 6-3)
automatically stops the boom and applies the boom hoist
brake when the boom is raised to Angle A.
Operation
See Figure 6-4 for the following description.
NOTE: Reference to LED is past production only.
When the boom is below the maximum angle, limit switch (5)
is closed and its LED (light-emitting diode) is ON (View B).
The boom hoist can be operated.
When the boom is raised to the maximum angle, boom butt
(1) pushes adjusting rod (2a, 2b, or 2c) in and actuator rod
(11, View A) opens limit switch (5). The LED then goes OFF.
Boom hoist operation stops automatically because the open
limit switch turns off power to the boom hoist electric circuit.
The boom hoist pump shifts to neutral and the brake applies
to stop boom movement.
Maintenance
At least once weekly, check that the automatic boom stop
stops the boom at the specified maximum angle. If not,
replace any worn or damaged parts and/or adjust the boom
stop.
Once the automatic boom stop is properly adjusted, it should
not require periodic adjustment. Adjustment is required,
however, when:
• The luffing jib is installed or removed.
• Parts are replaced.
Bypass Limit Test
Perform the following test to determine if the boom up limit
on your crane can be bypassed or not.
1. Lower the boom onto blocking at ground level.
2. Have an assistant push the adjusting rod (Figure 6-4
) in
to trip the boom stop limit switch open.
3. Rotate the limit bypass key (in crane cab) to the bypass
position and hold.
4. Try to boom up — do not raise the boom any higher than
necessary to perform the test:
a. If the boom rises, your boom up limit can be
bypassed.
b. If the boom does not rise, your boom up limit cannot
be bypassed.
The test is complete. Release the limit bypass key and the
adjusting rod to the normal operating positions.
WARNING
Falling Attachment Hazard!
If boom fails to stop for any reason, stop engine
immediately. Troubleshoot system to determine problem.
Do not resume operation until problem has been
corrected.
WARNING
Falling Attachment Hazard!
Do not operate crane unless automatic boom stop is
properly adjusted and operational. Do not adjust
maximum operating angle higher than specified. Boom
could be pulled over backwards or collapse, causing
death or serious injury.
WARNING
Crush Hazard!
Maintain constant communication between operator and
assistant during following steps.
Stay clear of moving parts.
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