Komatsu PC20R-8 Shop Manual page 11

HOISTING INSTRUCTIONS
Heavy parts (25 kg or more) must be lifted
with a hoist etc. In the Disassembly and As-
sembly section, every part weighing 25 kg or
more is clearly indicated with the symbol
1. If a part cannot be smoothly removed from the
machine by hoisting, the following checks should
be made:
. Check for removal of all bolts fastening the part
to the relative parts.
. Check for any part causing interference with
the part to be removed.
2. Wire ropes
1) Use adequate ropes depending on the weight
of parts to be hoisted, referring to the table be-
low:
WIRE ROPES
(Standard «S» or «Z» twist ropes
without galvanizing)
Rope diameter (mm)
10
11.2
12.5
14
16
18
20
22.4
30
40
50
60
The allowable load value is estimated to be
one-sixth or one-seventh of the breaking
strength of the rope used.
2) Sling wire ropes from the middle portion of the
hook. Slinging near the edge of the hook may
cause the rope to slip off the hook during hoist-
PC20R-8 PC27R-8
HOISTING INSTRUCTIONS
Allowable load (tons)
1.0
1.4
1.6
2.2
2.8
3.6
4.4
5.6
10.0
18.0
28.0
40.0
ing, and a serious accident can result.
Hooks have maximum strength at the middle
portion.
3) Do not sling a heavy load with one rope alone,
but sling with two or more ropes symmetrically
wound on to the load.
Slinging with one rope may cause turning of
the load during hoisting, untwisting of the ro-
pe, or slipping of the rope from its original
winding position on the load, which can cau-
se dangerous accidents.
4) Do not sling a heavy load with ropes forming a
wide hanging angle from the hook.
When hoisting a load with two or more ropes,
the force subjected to each rope will increase
with the hanging angles.
The table below shows the variation of allowa-
ble load (kg) when hoisting is made with two ro-
pes, each of which is allowed to sling up to
1000 kg vertically, at various handing angles.
When two ropes sling a load vertically, up to
2000 kg of total weight can be suspended.
This weight becomes 1000 kg when two ropes
make a 120ë hanging angle.
On the other hand, two ropes are subjected to
an excessive force as large as 4000 kg if they
sling a 2000 kg load at a lifting angle of 150ë.
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