What Is a Tandem Lift?
On occasions a load is too heavy or cumbersome to be safely lifted with one crane alone, and the help of another crane must be enlisted. The process of lifting a load between two or more cranes is referred to as a tandem lift. This concept is not new, however tandem crane lifting is complex. The greater the number of cranes, the more challenges there are to overcome. Though with precise planning and modern technology, tandem lifting is safer and easier to manage than ever.
Why Use Cranes in Tandem?
A tandem lift gives you a much higher lifting capacity than a single crane. If done right, a tandem lift offers greater stability than a lift carried out by a single crane that might be struggling at the edge of its safety rating.
Common scenarios requiring a tandem crane lift include:
- Structural Beams — Bridges and premade support structures, which are both awkward and heavy.
- Ships — It is safer to have two cranes — set far below their safety ratings — when it comes to lifting a ship. Ships will often have ballast and fuel that can cause their weight to shift a great deal during a lift.
- Critical Lifting — Many factors can put a crane over its lifting limit. Sharing the weight with another crane lowers the dangers that come with bad weather, unstable ground or awkward loads.
- Positioning — You may want to use a large single crane, however the working area may be too small or unstable to support it. Two smaller cranes can sit apart and spread the weight.
Types of Tandem Lift
When planning a tandem lift it is important to consider the best ways of using each crane, depending on the situation and the load. The two main methods of lifting in tandem are equalised and unequalised:
– Equalised Tandem Lift
This method employs the use of an equaliser beam with a central load link and pin. This requires a special beam, with crane hooks at either end.
Crane hooks from each of the cranes would lift one end of the beam. The load would then hang from the centre of the beam — distributing half of the weight between each crane.
– Unequalised Tandem Lift
This is a common way for two cranes to lift boats and ships in and out of the water. Each crane would have an independent lifting point on the load. The beams and hoists are separate for each crane.
The weight distribution is uneven — this is where planning and expertise play a major role. Newer cranes may also be able to communicate with each other; to help keep the load stable, level and safe.
Safety
As with all lifting scenarios, safety is the single biggest concern for the operators and those nearby. The added challenge of coordinating a tandem lift means that you need to use the best equipment and the best staff available. Preparation and planning must also be flawless.
Equipment
Each crane’s lifting capacity goes through a downgrading — to 75% of their limit — if they are to work on a tandem lift. It is also a good idea to use cranes of the same brand and model, if possible, as this helps to make a tandem lift safer.
The reason for this is that two identical cranes will move and lift at the same rate. There will also be fewer details to worry about, such as monitoring the quirks of different brands. Additional accessories and equipment used for each crane for the purpose of a tandem lift should be identical, with hoists, harnesses and beams being of the same weight and rating.
Planning
Good planning is crucial when you want to have two cranes working well together. The appointed person should oversee the entire project from beginning to completion. A supervisor or crane operator could be an appointed person for a tandem lift, however this person would have to be qualified for carrying out this type of task.
It is the duty of the appointed person to inspect the site in advance and learn the details of the load as well as the lifting requirements — including where the load will go. A lifting plan must be created that tackles various points, including backup cranes, crane placements and choosing the cranes’ team.
Obstructions may need moving and warning notices to residents or businesses may have to be issued. Local authorities should be contacted in order to obtain the appropriate permissions. Operators may also need to take extra caution when lifting around endangered wildlife.
Experience
The appointed person should be the most knowledgeable individual on site, however they will rely on the support of a highly skilled team. For a tandem lift, crane operators must hold up-to-date CPCS qualifications and possess extensive experience. Slingers and signallers must also have the relevant training.
The team selected by the appointed person must have prior experience working together on similar tandem lifts. They must be familiar with the plan and understand how the cranes should respond during the operation.
Choose Emerson
At Emerson Crane Hire we have over 35 years of experience in all types of complex lifting operations, including tandem lifts. We handle some of the most challenging single and tandem lifts in the UK. With a huge range of cranes and some of the country’s most experienced professionals, we have the equipment and personnel to handle any lift, no matter how complex. For expert help with your next lifting operation speak to Emerson today on 020 8548 3900.
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