Komatsu PC88MR-10 Shop Manual page 17

Measure the weight of the load by the eye and
check its center of gravity.
Use the proper sling according to the weight of
the load and method of slinging. If too thick wire
ropes are used to sling a light load, the load may
slip and fall.
Do not sling a load with 1 wire rope only. If do so,
the load may rotate or the sling gets loose and
the sling may slip off. Install 2 or more wire ropes
symmetrically.
Slinging with one rope may cause turning
of the load during hoisting, untwisting of
the rope, or slipping of the rope from its
original slinging position on the load,
which can result in a dangerous accident.
Hanging angle must be 60 deg. or smaller as a
rule.
When hanging a heavy load (25kg or heavier),
the hanging angle of the rope must be narrower
than that of the hook.
a When slinging a load with 2 ropes or more,
the larger the hanging angle is, the larger the
tension of each rope. The figure bellow
shows the variation of allowable load in kg
when hoisting is made with 2 ropes, each of
which is allowed to sling up to 9.8 kN
{1,000kg} a load vertically, at various
hanging angles. When the 2 ropes sling a
load vertically, up to 2,000 kg of total weight
can be suspended. This weight is reduced to
1,000 kg when the 2 ropes make a hanging
angle of 120 deg.. If the 2 ropes sling a 2,000
kg load at a hanging angle of 150 deg., each
rope is subjected to a force as large as 4,000
kg.
When installing wire ropes to an angular load,
apply pads to protect the wire ropes. If the load
is slippery, apply proper material to prevent the
wire rope from slipping.
Use the specified eye bolts and fix wire ropes,
chains, etc. to them with shackles, etc.
Apply wire ropes to the middle part of the hook.
PC88MR-10
00 Index and foreword
Foreword, safety and general information
a Slinging near the tip of the hook may cause
the rope to slip off the hook during hoisting.
The strength of the hook is maximum at its
central part.
Do not use twisted or kinked wire ropes.
When slinging up a load, observe the following.
1. Wind up the rope slowly until the wire rope
tensions. When putting your hands on the
wire ropes, do not grasp them but press them
down from above. If you grasp them, your
fingers may be caught.
2. After the wire ropes are stretched, stop the
crane and check the condition of the slung
load, wire ropes, and pads.
3. If the load is unstable or the wire rope or
chains are twisted, lower the load and lift it
up again.
4. Do not lift up the load at an angle.
When lowering a load, pay attention to the
following.
1. When lifting down a load, stop it temporarily
at 30 cm above the floor, and then lower it
slowly.
2. Check that the load is stable, and then
remove the sling.
3. Remove kinks and dirt from the wire ropes
and chains used for the sling work, and put
them in the specified place.
Precautions for using mobile crane
a Read the Operation and Maintenance Manual of
the crane carefully in advance and operate the
crane safely.
Precautions for using overhead traveling crane
The hoist or crane must be used to sling the
components weighing 25 kg or heavier. A
part weighing 25 kg or heavier in
"disassembly and assembly" section is
indicated with the symbol of
Before starting work, check the wire ropes,
brake, clutch, controller, rails, over winding
prevention device, ground fault circuit interrupter
.
00-15