SkyTrak 6036 Service Manual - Manual (Page 84)

Boom
3.44 Model 6036 Legacy
3.3.7 Boom Chains
This vehicle uses double extend chains to extend the
boom and a single retract chain to retract the boom. The
extend and retract chains are constructed of 3/4" pitch
links with 6 x 6 leaf lacing.
Note: DO NOT attempt to service or repair a chain.
Replace a stretched or damaged chain with a new one.
Replacement chains are shipped pre-assembled with
new clevis’.
a. Boom Chain Inspection
Figure 3-95 Every 250 Hours of Engine Operation,
Inspect Boom Chain Condition
Under normal operating conditions the boom chains will
need to be inspected every 250 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 mildly
corrosive or highly corrosive industrial atmospheres, in
addition to abrasive exposures such as sand and grit.
• Moisture - Corrosive rusting reduces chain
strength by pitting and cracking.
• Temperature - Low temperature reduces chain
strength by making the metal brittle. Going in and
out of cold storage results in moisture from
condensation.
• 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.
• 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.
• 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.
Environmental conditions and load cycles make it
impossible to predict chain life. Each specific application
should be evaluated, based on the degree of exposure,
the areas of possible operation and the types of load
cycles.
A chain replacement schedule should be established to
prevent chain failure. This schedule can be established
by frequent inspection. Based on the observations, the
frequency of inspection can be changed.
This inspection procedure development should go on until a
projected time of replacement can be predicted. A chain
by its very nature and exposure should be considered an
expendable item and a safe chain replacement schedule
should be established.
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.
Inspection Guidelines
1. Park the vehicle on level ground. Place the travel
select lever in (N) NEUTRAL, place the neutral lock
lever in the (N) NEUTRAL LOCK position, engage
the parking brake switch and raise the boom to a
horizontal (level) position.
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.
MM2130
250
MS21702