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Figure 6
Figure 7
PRE-OPERATION INSPECTION
Limit Switch Inspection
1.
Press UP button.
2.
While the hook moves up, raise the limit switch
paddle where the chain enters the hoist.
3.
Hook should immediately stop.
4.
Check DOWN limit switch in similar manner.
Inspecting the Load Chain
Clean the chain with a solvent, and carefully inspect the
entire load chain. The chain should be visually checked
before each day's use. Replace damaged chain before
using the chain hoist.
Replace the load chain if any of the following are identified:
1.
Seriously rusted or cracked.
2.
Marks on the chain surface are deeper than 5% of the
link's diameter.
3.
Links are twisted or deformed.
4.
The links are stretched too long or seriously worn on the
surface, especially at the points where links contact each
other. To check the links for stretch, proceed as follows:
5.
Select an unworn, unstretched length of chain (at the
slack end for example). Let the chain hang vertically
with a light load (about 20 pounds) on the chain to
pull it taut.
6.
Use a large caliper to measure the outside length of a
convenient number of links. Measure the same number
of links in a used section of chain and calculate the
percentage increase in length of the worn chain.
7.
If the length of the worn chain is more than 1-1/2%
longer than the unused chain, then the chain should be
replaced. If the chain is worn less than 1-1/2%, check it
at several more places along its length. If any section is
worn more than 1-1/2%, the chain should be replaced.
Never extend load chain by welding a second piece
to the original.
Do not operate the hoist with a
twisted, kinked, or damaged load chain. Do not
splice the load chain.
Check that the chain does not twist along its length from
hoist to hook. If a twist is present on units with multiple falls,
the hook must be passed back through the chain loop to
remove all twists in the chain.
The load chain supplied with your
JET chain hoist is designed, manufactured, and tested
for proper fit and durability. Over a period of time the
chain may need to be replaced. For your own safety,
use factory replacement chain only. Use of other than
factory replacement chain may cause serious injury
and/or damage to the hoist.
Inspecting the Hooks
It is important to check top and bottom hooks for proper
opening and other signs of deformation or damage.
Replace a hook immediately if any of the following problems
are identified:
1.
The safety latch no longer contacts the hook opening.
2.
The vertical angle at the neck of the hook reaches 10°
(see Figure 8).
3.
Chemical corrosion or cracks on the hook.
4.
Excessive wear on the inside surface.
5.
The throat opening has enlarged wider than the
maximum permissible 10% increase, as shown in
Figure 9.
7
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