What are the Tying Types of the Ropes and What is the Load Capacity according to the Lashing Type?
The correct use of ropes, which are commonly used in lifting equipment, is very important. It is not enough to give due importance only to lifting machines (such as forklifts, chain hoists and cranes). Because not only these machines but also slings and ropes are of great importance in transportation and lifting. The term sling also includes steel ropes, chains, webbing and fibre ropes. Since improper slinging can be dangerous, rope lashing forms are considered on a large scale in this regard.
Rope Tie Types and Capacity Calculation
Slings have lashing types according to their use and load-carrying capacities according to tying styles. Ways of tying the ropes are vertical lashing, choke lashing, U-lift and hug lashing.
Vertical Lashing: Any load to be lifted or transported is lifted vertically using a single sling. With this sling lashing and lifting, items that do not exceed the safe working capacity of the slings can be lifted. However, the rotation of the lifted or transported goods at the time of lifting may cause the sling to bend. In such a case, damage to the sling may occur. Therefore, it is necessary to be very careful in this kind of use.
Choke Lashing: The carrying capacity of the rope to be used in this lifting process must be calculated according to the angles of use. Straps suitable for this capacity should be used. Rope lashing capacities need to be calculated for operations to be transported or lifted in the form of choke lashing. The angle formed in this type of binding style is less than 120 degrees, which requires you to be more careful in your calculations.
Choke Angles and Capacity Utilisation Factors:
- 120-180 degrees = 100%
- 90-119 degrees = 87%
- 60-89 degrees = 74%
- 30-59 degrees = 62%
- 0-29 degrees = 49%
U Lifting and Hugging Lashing: In U-shaped lifting operations, the goods carried are evenly distributed on the two arms of the sling. However, the lifting angles of the arms reduce the rope capacity in direct proportion to the size of the angle formed. For example, as the angle between the eyes and arms of the ropes continues to increase, the weight of the item to be lifted decreases. Wrapping the load to be carried in a single sling embrace gives the same result in lifting with 2 or 3 slings.
Lever Angles and Load Anchor in U Lift and Hug Lashing:
- 0 Degree – 1000 Load Anchor
- 5 Degree – 1003 Load Anchor
- 10 Degree – 1015 Load Anchor
- 15 Degree – 1035 Load Anchor
- 20 Degree – 1064 Load Anchor
- 25 Degree – 1103 Load Anchor
- 30 Degree – 1154 Load Anchor
- 35 Degree – 1220 Load Anchor
- 40 Degree – 1305 Load Anchor
- 45 Degree – 1414 Load Anchor
- 50 Degree – 1555 Load Anchor
- 55 Degree – 1743 Load Anchor
- 60 Degree – 2000 Load Anchor
If all the ropes used in this type of application lift the load vertically, the weight of the load is divided by the number of ropes and the load on each sling is calculated. Rope selection is made after the capacity calculation is made by determining the angle formed by the rope arms on the vertical axis. After the angle calculation is made, the necessary rope selection is made by using the arm angles and load multipliers above. For example, each rope to be lifted at an angle of 45 degrees for a 1-tonne item must have a minimum capacity of 707 kg.
What are the Points to Be Considered in Rope Lashing?
- Hooks or other lifting devices in the laden position must never be caught in the sewn overlaps and the seams of the sling arm.
- The contact area of the ropes in the form of bands should be flat. Thus, the entire cross-section of the rope is loaded evenly.
- Care should be taken so that the round slings do not get tangled in the crane hook. The mouth of the hook must have sufficient space in the load. Thus, a balanced load can be made in the full width of the round sling, taking its natural straight profile.
- Flat belt ropes should be applied in such a way that they can bear the load of the entire sling width. Wider and vertical angles will stretch the edges of the ropes and cause breakage.
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