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(8)
Chain wear scale
The chain can be checked for wear or stretching with the use of a chain wear scale. Stretching of
a chain is due to the elongation of the pitch holes and wearing of the pin O.D. The greatest
amount of stretching occurs at the areas of the chain that flex over the sheaves most frequently.
Check the chain at this point with a scale. The wear scale has instructions printed on the sides for
use in determining chain stretch and are as follows :
Determine pitch length of chain using 6 inch scale on one side of wear scale.
If pitch is 1/2(12.7mm), 3/4(19.05mm), 1(25.4mm), 1-1/2(38.1mm), 2(50.8mm), use side A of
scale.
If pitch is 5/8(15.875mm), 1-1/4(31.75mm) or 2(50.8mm), use side B.
Align point A or B to center of a pin and note position of the opposite A or B point.
If other point also lines up with a pin, the chain is worn and should be replaced.
If any of the above conditions exists(cracked plates, turned pins, stretching etc), the chains should
be replaced in pairs as a complete assembly. Order chains by part number to insure the correct
chain length, pitch and material specifications.
7)
L
L
OAD CHAIN LUBRICATION AND ADJUSTMENT
(1)
Lubrication
The most important consideration in field maintenance of lift chains is lubrication. Hard working,
heavily loaded chains cannot be expected to give satisfactory wear life without scheduled periodic
re-lubrication. Like all bearing surfaces, the precision manufactured, hardened steel, joint-wearing
surfaces require a film of oil between mating parts to prevent rapid wear. Oil must penetrate the
chain joint to prevent wear. Applying oil to external surfaces will prevent rust, but oil must flow into
the live bearing surfaces for maximum wear life. Frequency of re-lube will vary with operating
conditions and environment, the best estimate of lube period is 200 hours. Trucks parked
outdoors or trucks in extremely severe service, may require more frequent re-lube to maintain an
oil film on all chain surface.
Wipe off the old oil with a clean cloth and blow out the remaining dirt with compressed air.
Wear eye protection.
With a clean brush, apply EP-140 extreme pressure lubricant or heavy motor oil(40W).
(2)
R
R
eplacement
Replace chains as a pair. It will be virtually impossible to maintain uniform loading between the
strands if a new chain is put into service opposite an old chain. The jonts in the old chain will be
greater than that on the new chain, greatly complicating the problem of maintaining equal chain
tension. The new chain will wear more slowly causing it to bear the major portion of the load
resulting in premature wear and fatigue failure. Don't steam clean or decrease new chains.
The manufacturer's grease is effective in reducing wear and corrosion. If the original factory lube
is dried out or wiped off, soak the new chain in heavy engine oil for at 1/2 hour prior to installing on
truck. After the old chains have been stripped from the mast, very carefully inspect chain anchors
and sheaves. Broken, cracked or worn anchor must be replaced using the new anchor pin and
split pin. Do not paint newly replaced chain after it has been installed.
8-18
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