Lull 644E-42 Operation Manual - Manual (Page 157)

General Maintenance
155 Model 644E Origin 3/04
The above load cycles and environmental conditions make it impossible to predict
chain life. It is therefore necessary to conduct frequent inspections until replacement
life can be predicted.
The boom chainís normal life expectancy can be expressed as a maximum percent
of elongation. This is generally 3%. As the chain flexes back and forth over the
sheave, the bearing joints (pins and inside link plates) gradually incur wear due to
articulation.
Inspection Guidelines
1. Park the vehicle on level ground. Place the travel select lever in the (N)
NEUTRAL DETENT position, engage the parking brake switch and raise
the boom to a horizontal (level) position.
2. Fully extend the boom until the extend chain is taut. Shut the engine off.
The extend chains will be visible for inspection with the vehicle in this state.
While doing the chain inspection, check all chain clevis ends for distortion
or cracking and sheaves for bearing wear or grooving from the chain.
3. Inspect the retract chain every 1000 hours of operation. Refer to the Ser-
vice Manual for proper procedure.
4. Inspect the chains for the following conditions:
Edge Wear - Extend Chain Only
Check the chain for wear on the link plate edges caused by running back and
forth over the sheave. The maximum reduction of material should not exceed
5%. This can be compared to a normal link plate height by measuring a portion
of chain that does not run over the sheave.
The new extend chain link measures .950" (24 mm) (1). If the measurement of
the worn chain is less than .903" (23 mm) (2), the chain must be replaced.
MM2051
1
2