SkyTrak 6042 Operation Manual - Manual (Page 165)

General Maintenance
163 Model 6042 Origin 2/04
Following are some examples of dynamic shock loading which can impose
abnormal loads above the endurance limit of a leaf chain.
• High velocity movement of load, followed by sudden, abrupt stops.
• Carrying loads in suspension over irregular surfaces such as
railroad tracks, potholes, and rough terrain.
• Attempting to “inch” loads which are beyond the rated capacity of
the vehicle.
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 chain’s 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.