Rated Capacities for Slings

Use the following calculator to determine the rated capacity required by the sling(s).  You will need a sling or slings with a rated capacity equal to or greater than the rated capacity required for the corresponding rigging technique.

Weight of Load (lbs)

Number of Legs Supporting Load

Minimum weight on each leg: 0 lbs.
Maximum weight on each leg: 0 lbs.
Minimum Rated Capacity Requred: 0 lbs.

To calculate the load on a particular sling leg proceed as follows:

1. Take the total weight of the load and divide this by the number of legs supporting the load. For example, assume a 2,000 pound load is to be supported by 2 legs of a sling. The above will give a total minimum weight on each leg of the sling of 2,000 pounds divided by 2 legs or 1,000 pounds.
2. Determine the load factor by observing the load factor chart below. Ex. Assume that the leg angle will be 60°. The load factor for 60° from the load factor chart is 1.154.
3. Multiply the load factor times the minimum weight to be supported by the leg, i.e. 1,000 pounds times 1.154=1154 pounds. The rated sling capacity needed is then 2,308 (1,154x2) pounds in basket capacity to safely lift the 2,000 pound load.

 

LEG ANGLE

LOAD FACTOR

90°

1.000

85°

1.003

80°

1.015

75°

1.035

70°

1.064

65°

1.103

60°

1.154

55°

1.220

50°

1.305

45°

1.414

40°

1.555

35°

1.743

30°

2.000

When you need to lift something at home in the garage, then a chain block is the perfect lifting machine for you. You need to take great care to make sure that the load stays within the rated capacity of the chain block, and that is when you ask: “How do you calculate chain blocks?”

The safe working load of any lifting machine is marked on the machine. It means that the strenuous task of doing calculations is taken off the shoulders of the end-user. Lifting machines and equipment manufacturers have a legal obligation to mark products with load capacities.

Lifting machines can become dangerous when people do not follow the manufacturers’ instructions on the safe use of chain blocks. This article aims to create awareness for the users of chain blocks and to help ensure that you can accurately calculate loads so you can use the chain blocks safely.

Calculating The Safe Load For A Chain Block

When you need to lift loads using a chain block, it is important to keep the safety of the load in mind. It is required by law for any manufacturer of lifting machines and equipment to display a rated capacity on the machine or equipment. The manufacturers do this by stamping the abbreviation SWL on the lifting machine.

It would not make sense to expect people with little or no knowledge about chain blocks to make complex calculations regarding the load that a chain block can safely lift. That does not mean that the end-user should hook any weight onto the chain block.

The end-user of lifting machines should ensure that the intended load they want to lift with a chain block is not heavier than the rated load indicated on the lifting machine. Failing to do it will lead to the failure of the mechanical parts of the chain block and can also cause severe injuries.

If a chain block is rated for 1500 pounds, the load needs to be calculated to be less than 1500 pounds. It is done by looking at the weight of the load and adding it to the weight of the slings and the connectors like the shackles. It means that you must add everything lower than the hook of the chain block to this calculation so it’s accurate and won’t cause accidents.

Can Modifications Impact Chain Block Calculations?

The calculations that are done by the manufacturers of lifting machines like chain blocks are done when approved components are used. Calculations will be impacted negatively when components like the chain of a chain block are modified.

The chain used for lifting is made specifically for that purpose and is marked with either an 80 or 100 on the chain links. When people use a chain other than a lifting chain, it changes the capacity that the chain block can safely lift. That is why no other person is permitted to make modifications to any lifting machine.

Engineers are trained and qualified to understand calculations, and that is why engineers need to be involved in anything that has to do with load capabilities. It is impossible for an inexperienced and untrained person to understand load-bearing capabilities, specifically if components are modified.

Important Factors When Calculating Chain Block Capacity

When you need to lift a load with a chain block, you must take certain factors into consideration to ensure that the lift can be done safely using the calculations from experts. The experts are designers, engineers, and manufacturers. Here are the factors that need to be considered:

• The designers of chain blocks designed these lifting machines with specific needs in mind. These lifting machines are designed to lift loads within a specified calculated load.

• The engineers work out and calculate the safe load characteristics to ensure that the design will work. It is done to minimize mistakes along the way.

• The manufacturers use the design and the information from the engineers to make the lifting machines like the chain blocks that we use. The manufacturers also provide information to the end-user.

• The end-user of lifting machines needs to follow the information provided to them by the manufacturer, who used specifications and calculations from the designers and engineers.

• The first part of calculating for the end-user is when they need to identify an anchor location for the chain hoist. You should identify where the anchor location should be by adding the weight of all connectors, slings, the load you will be lifting, and the chain block together.

• You can now secure the chain block to a suitable anchor point and then lift the loads that fall within the calculated safe working load(SWL) of the chain block.

• Only approved shackles and slings should be used when lifting any load with a lifting machine. Remember that the weight of the shackles and the slings must be added to the weight of the load when you calculate whether the weight falls within the SWL.

• When you do not follow the manufacturer’s recommendations, you are ignoring the information and the specifications of the designer and the engineer as well. The experts recommend that anyone working with any type of lifting machine needs to get proper training on how to calculate and use one correctly.
  
• When loads are lifted without following the correct procedure, it could result in serious injuries and property damage.

Conclusion

In this post, you have seen that to understand the calculations of a chain block; you need to read the instruction from the manufacturer of the chain block. The manufacturer gets information and specifications from designers and engineers to make the end product. The manufacturer has to inform the end-user.

The end-user must use the information on the chain block and inside the user manual to set up the chain block correctly and then use it in the right way to stay within the calculated load capabilities of the chain block. If you do not follow the specifications, it could have serious consequences, including damage or injuries.

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