SkyTrak 6042 Operation Manual - Manual (Page 160)

158 Model 6042 Origin 5/02
General Maintenance
C. Boom Chain Inspection
(250 Hour Intervals)
Under normal operating conditions the boom chains will need to be
inspected every 250 hours of operation. The retract chains need to be
exposed and inspected every 1000 hours of operation. Refer to the Service
Manual for the proper procedure. Environmental conditions and dynamic
impulse/shock loads can drastically affect normal operating conditions and
require more frequent inspection intervals.
Environments in which material handling vehicles operate can vary widely
from outdoor moisture to temperature to mildly corrosive or highly corrosive
industrial atmospheres, in addition to abrasive exposures such as sand and
grit.
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% of pitch. As the chain flexes back
and forth over the sheave, the bearing joints (pins and inside link plates)
gradually incur wear due to articulation.
WARNING:
Worn pins, stretched or cracked links or corro-
sive environments can cause chain failure. A chain failure could
result in uncontrolled boom movement, loss of load or vehicle
instability and could cause death or serious injury and/or property
damage.
250
OH2710
OA1490