Obendreherkrane mit Katzausleger rent in Iserlohn

Top-slewing cranes for hire – the powerhouse among the cranes



Top-slewing cranes are specialised lifting machines for moving goods vertically and horizontally. They are a type of rotating tower crane, and are sometimes referred to simply as tower cranes. The slewing ring enables the hook of these cranes to reach any point within the range of the jib. As the name suggests, top-slewing cranes are distinguished by the position of the slewing ring, which is not found near the base, but at the top of the mast. The mast therefore does not rotate with the crane. Top-slewing cranes can be dismantled, which makes them convenient cranes for hire, as they can be transported to the operating site in parts. At klarx, we offer top-slewing cranes for rent of all sizes.

Advantages over other rental cranes

-       Compared to self-erecting cranes, in which the slewing ring is found at the base, top-slewing cranes require a smaller set-up area. This is thanks in part to the position of the counterweights, which are fixed to the counter jib above, and also to the fact that the mast itself does not have to rotate. Top-slewing cranes are more flexible about their chassis, and offer significantly higher load capacity than even the largest self-erecting cranes available for hire. The modular design enables clients to customise the crane for their specific intended use.

-       Compared to other rental cranes, including mobile cranes with telescoping booms, top-slewing cranes have considerably lower hourly rental costs, while the area occupied by the base on the ground is very substantially smaller. Tower cranes excel at lifting loads over obstacles, making them superior cranes for longer deployments on-site. Using a top-slewing crane tends to become cost-efficient from a hire duration of about one month.

-       Compared to bridge cranes, pick-and-carry cranes, mobile cranes on excavator chassis, trailer and spider crane rentals, tower cranes offer not just a much higher load capacity, but also a greater lifting height and better range. Unlike Diesel-powered alternatives, these tower cranes run on electricity, which keeps running costs low and avoids any harmful emissions on-site.

The components of a top-slewing crane

A top-slewing crane or tower crane consists of the following components, which are assembled at the site of use.

The Chassis

The bottom part of the crane is the chassis. This often comes with concrete weights as well as a weighted foundation. Depending on the size of the crane and the length of the jib, the x-pattern foundation used will have a square-shaped footprint ranging from 3m x 3m to 10m x 10m. There are various solutions for specialised uses, including rail-going chassis, portal foundations or gantries which allow vehicles to pass underneath the crane, and concrete foundation anchors. These anchors are single-use and are left in the ground when their work is done. Anchors can facilitate an extremely small footprint during operation – less than 2m x 2m! With the help of foundation anchors, even large tower cranes can be erected in spaces as constrained as a lift shaft.

The Mast

The mast of a top-slewing crane is usually built as a steel framework and consists of individual segments which can be assembled in different configurations, depending on the use case. On the one hand, this means that large tower cranes can be built for very low heights, which comes in handy for applications like temporary storage spaces. When needed, on the other hand, tower cranes also can be built as tall as 85 meters or more. The mast contains the crane’s wiring system as well as a ladder or stairs for the operator or – in rarer cases – a lift.

The Jib

The function of the main jib is to move loads horizontally. Like many other parts of the crane, it too consists of a modular steel lattice, whose segments can be combined in different configurations depending on the use case. The load capacity of the jib depends on the specific construction and the material thickness. The capacity is highest near the mast and is continually reduced the further from the mast the load is lifted or carried. Maximum load capacity should be one of the main criteria when choosing a suitable rental crane for the job at hand. The most common variant found on top-slewing cranes are so-called trolley jibs. These jibs form a right angle with the mast, and remain fixed in this horizontal position. A crane trolley is driven along the jib, transporting the hook block and any loads attached to it. In applications like high-rise construction, fly jibs are used to reach greater heights. On this type of jib, also known as a luffing jib, the hook block is fixed directly to the jib (without a trolley) and therefore cannot be moved to different positions along the jib. Instead, the jib itself can be lifted, so that it points upwards and forms an obtuse angle with the mast. This has the effect of moving the hook block closer to the mast. The operation of a tower crane with a fly jib is more demanding, and they tend to be used rarely. However, they have the unique advantage that they do not necessitate a full cylinder-shaped clear air, so that less space is required to rotate past tall obstacles like church towers or chimneys.

The Counter jib

The counter jib also consists of a steel framework, and is a quintessential component of any top-slewing crane. It is found directly opposite the main jib, and bears the counterweight. The counter jib is shorter than the main jib. Frequently, it also serves to carry the crane’s engine or winch.

The Slewing Ring

The beating heart of the crane. The slewing ring enables the crane to rotate 360 degrees and lets the hook reach any point within range. Upon request, cranes can be hired with a turning circle limiter. This makes it possible to block angular segments of the full rotation, in order to avoid hitting specific obstacles like a high buildings or the mast of another crane. Please note that this necessitates careful planning, as a turning circle limiter may reduce the load capacity of the crane.

The Rope

The hoist rope of the crane carries the entire load, making it the crane’s most burdened component. One common variant in use heavy-duty wire rope. This type of rope has to be lubricated regularly, as well as inspected for its discard criteria. The hoist rope can be led through the hook block several times to increase the capacity of the crane. This pulley method will slow down the speed of work, as larger lengths of rope have to be pulled to lift the load the to the same height. Heavy-duty textile rope has been one of the latest trends in crane development, but has not yet found widespread application in rental cranes.

The Operator’s cabin

The operator’s cab is the control centre from which all movements of the crane are controlled. It is situated at the top of the mast, where the operator has a good view of the crane’s entire range of operation. It is technically possible to control some tower cranes remotely, but this is only advised for storage sites or very simple construction sites with clear visibility from the ground. Especially when working in concert with other cranes, the bird’s-eye view from the cab becomes indispensable to ensure good coordination and the correct application of priority rules.

The Tip

The tip is the central pivot where many of the crane’s wire ropes meet. These connect the jib and counter jib to each other and serve to support the steel framework construction. Many more recent top-slewing cranes have special reinforced jibs, and have dispensed with this additional anchoring. This innovation has reduced the height of the cranes, which is especially helpful when using several cranes with overlapping turning circles. If one crane can be lower, taller cranes do not have to reach as great a height to rotate freely above them. The expressions “Flat Top” and “High Top” were originally specific to the Liebherr brand, but have increasingly established themselves as a convention across the industry.

Warning Lights

The use of a tower crane in the approach path of an airport or a helipad may require not only a special permit, but also specialised hazard lights to alert air traffic. Adding these is an available option on almost all cranes. During the planning phase, we recommend that special attention be paid to helipads of inner-city hospitals, which are easily overlooked.

The assembly of a top-slewing crane

Top-slewing cranes – including rentals – require a complex assembly, which often has to take place over several days. This involves a specialised assembly team as well as several articulated lorries and a mobile crane. Careful planning and preparation are of the essence. The soil in the area intended for the crane has to be compacted in advance of assembly. The reaction forces of the crane have to be matched by the static load bearing capacity of the ground underneath. Otherwise, it may be necessary to pour additional concrete foundations. Numerous factors have to be taken into account when preparing the assembly of a tower crane. In cases where additional concrete foundations are required, this includes having to wait for the concrete to fully set. For all of these reasons, we recommend that if you want to rent a top-slewing crane, you get in touch well in advance, allowing for a minimum preparation time of about four weeks. Please note also that good vehicle access to the site can help significantly reduce the cost, as in other cases very large mobile cranes may have to be rented for the erection of the crane.

Brands of top-slewing cranes available at klarx

At klarx, you can find top-slewing cranes for rent from the following manufacturers:

Liebherr, Potain, Comedil, AGS, Peiner, Manitowoc, Wolff, Raimondi, Alfa, BBL, Wilbert

Sample technical specifications

One widely popular top-slewing crane which is available for rent is Liebherr 200 EC-H 10 Litronic. The specifications of this crane are as follows:

-       Max hook height 68.00 m

-       Max load 10,000 kg

-       Max jib working radius 60.00 m

-       Max load when used at max jib working radius 2,650 kg

Renting top-slewing cranes at klarx

At klarx, you can hire tower cranes of all sizes, quickly and comfortably. Our specialised advisers will help you at each step, from choosing the right spot all the way to the assembly of the crane. With a few clicks, you can take the very first step right now on our website, and start your rental inquiry. As our client, you will be able to monitor all your projects on the klarx dashboard and use it to manage your entire fleet of hired equipment on-site. We believe that our commitment to complete transparency about costs, our fair rental terms, and a swift, fully digital process make klarx a reliable, competent partner in tower crane rentals, as well as supporting you in planning your construction site. Why wait, if you can start your rental inquiry with klarx today!