This is the first article in a regular series by Stuart Edwards of Edwards Heavy Lift on rigging matters. Stuart Edwards is well known to the industry, initially in presenting Boom Logistics and John Holland entries in the CICA Lift of the Year, before starting his own business and consulting to many of you. He was co-winner of the Innovation Award at the most recent CICA national crane conference, as well as one of the presenters at a rigging workshop there. If you have a rigging topic that you would like to see covered, please contact the editor or Stuart Edwards at firstname.lastname@example.org.
One of the perennial issues that our industry often comes up with innovative solutions for is limited head height. This may be because the crane does not have sufficient capacity to operate with increased boom length, or there is an obstruction that the load needs to fit under. In this article, we look at some of the options available.
Dual crane lift
One of the more obvious solutions with a long load that would require long rigging and boom lengths is a dual crane lift. Although the standards rightly require an assessment of whether the dual crane lift is necessary, on many occasions a thorough risk assessment will determine that a dual crane lift is not only more cost-effective and technically feasible but also safer. Pictured is a dual crane lift of deck units. As one can see, clearance to the powerlines was a challenge for this project. Using the two cranes ensured a safe and efficient lift.
A lifting beam may on occasion be a great solution to minimise head height. However, as the length between lift points becomes longer, the feasibility decreases due to the mass of the lifting beam or spreader. One thing to be careful of here is that if the centre of gravity of the load is higher than the lift points, a lifting beam or spreader with low sling angles may not provide sufficient stability. The lifting beam on the left provides a lower lift height.
However, as the dimension ‘a’ is greater than ‘b’, the lift is not stable and should not be attempted.
Sometimes you may need to lift under an obstruction. A typical example would be lifting concrete panels on high rise buildings where the crane hoist rope would clash with the structure if attempting a lift of the panel to its final placement position. Pictured is one solution using the existing rigging equipment of a crane company without any other specialised equipment. In this arrangement, a counterweight is rigged to the rear of the lifting beam. When the beam is not lifting a load, the beam hangs rotated backwards. To lift a load, the rigging is connected then the crane hoists and the beam rotates till everything is balanced. The load can then be lifted under the obstruction and the process reversed to release the lifting beam. For further explanation, a 3D animation of this can be found at edwardsheavylift.com.
More advanced versions of this concept are available, for example using rack and pinion remote controlled drives to control the travel of a counterweight.
Sometimes you may want to get under an obstruction such as a shed roof or door, but then need to extend the boom to achieve sufficient height and/or radius. With a full power boom, this is naturally possible as a matter of course – something that is used to great effect in the Franna crane. However, this is also possible for many cranes with a pinned hydraulic boom. Many manufacturers supply an unpinned boom chart, which may reduce the capacity significantly compared to the pinned boom chart; but will solve your problem nonetheless. Practically speaking, it is always best to only extend or retract a boom under load when necessary. Ensure that the wear pads are suitably maintained and keep the boom angle up as high as possible. Only ever do this in strict accordance with the manufacturer’s guidelines.
Sometimes using an attachment on the boom head of a crane can be an excellent solution. Load28 has won several CICA Lift of the Year awards for its glass lifting attachments. Gillespies has recently developed a solution for a client installing wall panels in a tunnel. As one can imagine in a tunnel, head height is extremely limited. Gillespies’ solution is as simple as it is ingenious: an attachment that pins where the Rhino attachment would normally go; and adds 600mm in lift height.
Jacking and trailer solutions
There is a whole another world we could explore. However, using platform trailers or SPMTs can be a simple and cost-effective solution, as can the use of jacking systems.