Lull 644E-42 Operation Manual - Manual (Page 156)

154 Model 644E Origin 3/04
General Maintenance
C. Boom Chain Inspection
Extend Chains
(250 Hour Intervals)
Retract Chains
(1000 Hour Intervals)
Under normal operating conditions the boom extend chains will need to be
inspected every 250 hours of operation and the boom retract chains every 1000
hours of operation. Environmental conditions and dynamic impulse/shock loads can
drastically affect normal operating conditions.
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. Some effects
can be as follows:
ï Moisture - Corrosive rusting reduces chain strength by pitting and cracking.
ï Temperature - Low temperature reduces chain strength by embrittlement.
Going in and out of cold storage results in moisture from condensation.
ï Chemical Solutions or Vapors - Corrosive attack on the chain components
and/or the mechanical connections between the chain components.
Cracking can be (and often is) microscopic. Going from microscopic
cracking to complete failure can be either abrupt or may require an
extended period of time.
ï Abrasives - Accelerated wearing and scoring of the articulating members of
the chain (pins and plates), with a corresponding reduction in chain
strength. Due to the inaccessibility of the bearing surfaces (pin surfaces
and plate apertures), wear and scoring are not readily noticeable to the
naked eye.
Dynamic shock loading can impose abnormal loads above the endurance limit of a
leaf chain.
ï High velocity movement of load, followed by sudden, abrupt stops.
ï Carrying loads in suspension over irregular surfaces such as railroad
tracks, potholes, and rough terrain.
ï Attempting to ìinchî loads which are beyond the rated capacity of the
vehicle.
WARNING:
Worn pins, stretched or cracked links or corrosive
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
OU0850
1000
OH2690
OU0870