JLG G12-55A Service Manual - Manual (Page 61)

3-25 G10-55A, G12-55A
Boom
3.10.4 Boom Extend Chain Installation
The following section explains the installation of the
retract chains without removing the boom assemblies.
Inspect and lubricate the chains thoroughly before
the installation.
1. Fasten the previously used rope to the end of the
extend chain.
2. Carefully pull the chain into the boom to the chain
clevis anchor.
3. Fasten the chain to clevis with a pin and cotter pin.
4. At the other end of the chain, connect the chain to
the clevis fastening the chain to the clevis with a pin
and retaining ring.
5. Install the chain clevis fastening and adjusting
hardware on both ends.
6. Remove any clamping devises being used to keep
the boom sections from moving.
7. Properly connect the batteries.
8. Adjust the extend chains as needed. Refer to
Section 3.7, “Hose Carrier Assembly Removal/
Installation.”
9. Remove the Do Not Operate Tags from both the
ignition key switch and the steering wheel.
3.11 BOOM CHAIN INSPECTION
AND LUBRICATION
3.11.1 Boom Chain Inspection
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. 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. Some effects can
be as follows:
• Moisture—Corrosive rusting reduces chain
strength by pitting and cracking.
• Temperature—Low temperature reduces the
chain strength by embrittlement. 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 an d
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.
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 machine instability.