SAFETY
USAGE OF CRANES
General introduction
Cranes or Roller bridges are used to handle heavy loads with a minimum of physical efforts.
Careful operation of crane requires wise planning and execution together with common
sense. Thus handling heavy loads is no longer manual labour, but has more and more become
brainwork.
Weight and center of gravity
The weight of an object is the quantity of gravity to which an object is submitted.
The relation between weight and mass:
G=Mxg
Where,
G weight in Newtons,
M mass in kilograms,
g acceleration due to the gravity field in m/s 2 (approximately 9.81 on earth).
The center of gravity of an object is the point where the mass of that object is in balance.
Safe handling of Cranes:
The center of gravity has to be located vertically under the crane hook.
E.g. In the middle of a ring wheel
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SAFETY
!! The crane hook has not only to be vertically above the center of gravity, but the lashing
points have also to be located above the center of gravity
Where is the center of gravity in the piece of work beneath?
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Note the Maximum permitted load first.
Don’t lift the load higher than necessary.
For transport above the floor, just above the floor is sufficient (be careful with pallets,…),
accompany the load with one hand.
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Where to park?
After having used the crane, lift the hook with lifting yoke up to the main height (+/- 4 m -
Hubtex-) and put the crane in rest position. Hang the lifting yoke and the control panel out of
the working area.
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SAFETY
Reporting irregularities:
Bring to notice about any abnormal situations during the usage.
(i.e) Strange noises, faults, troubles, etc.,
Example:
A continuously longer braking distance indicates that the brakes have to be adjusted or that
other troubles have arisen.
Hard to operate buttons
Switch off roller bridge (remove operation device) and report to the cell foreman Technical
Services
a More than 12 cores broken over a length of 30 x diameter.
b Hitches, crushes, torsions and any other deformation of the steel cable
c Excessive corrosion. Structure.
d Damage due to heating-up.
e Reduction of the nominal diameter by more than 10%.
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SAFETY
Types of lashing means (accessories)
1. Straps
2. Lifting belts
3. Lifting magnets
4. Chains
5. Eye-bolts
6. Lifting yokes and aids
Straps
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Color coding for Straps:
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Avoid the tearing apart of straps. NEVER use straps without protection on a sharp side
What is meant by a sharp side?
When the radius is smaller than or equal to the diameter of the round strap
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SAFETY
Lifting belts
Specifications:
- wear the same colour code as straps have a larger bearing surface than traditional round
Straps have the same lashing factor as round straps.
Lifting belts with adjustable Secutex are very appropriate when turning big / heavy rings.
How to turn heavy loads?
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SAFETY
Chains
Chain hooks without safety flap, such as e.g. foundry hooks, may only be used there where
no other possibility exists and a close follow-up is applied.
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SAFETY
Always attach chain hooks from the inside to the outside:
The suspension ring with which the lashing material is suspended in the crane hook has to be
wide enough:
to avoid deformation or damage of the suspension ring or loading hook
to avoid injuries when hooking the loading hook
to avoid increased wear of the crane hook
Correct method of using Suspension ring and hook:
principle: The inside width of the suspension ring has to be at least 20% larger than the
crane hook profile on which the suspension ring rests
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SAFETY
Eye-bolts
For regular eye bolts, the Maximum permitted load depends on the diameter and the length of
the thread as well as the properties of the metal with a perpendicular tensile strain
When the eye-bolt is not screwed against the contact surface!!
Caution:
With classic eye-bolts, the lifting capacity (traction power) decreases when the angle
increases.
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SAFETY
Perpendicular Traction with Traction with
traction an angle of an angle of
45° 90°
loss of 58% loss of 62%
Therefore, the lifting practice as given below has to be avoided.
And Finally . . .
Never stand beneath a hanging load.
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