Self-Erecting Tower Cranes

A self-erecting tower crane is a tower crane that arrives on site folded up and raises itself into working position, without the help of a second crane. The mast and jib unfold hydraulically or with the crane’s own winches, often in a few hours and with a small team. Once erected, it works like a conventional tower crane: a vertical mast, a horizontal jib, a trolley running along the jib and a hook that can reach any point within its radius.

These cranes are designed for houses, small apartment blocks, renovation work, agricultural buildings and other projects where a large top-slewing tower crane would be too big, too expensive or too slow to install, but where a crane is needed for weeks or months.

Brief History of Self-Erecting Tower Cranes

Tower cranes spread across Europe during the post-war reconstruction of the 1950s, and manufacturers soon looked for ways to make them faster to move between small sites. Folding designs that could be towed on axles and erected with their own winches appeared in that period, with French, German and Italian manufacturers among the pioneers. Potain in France and Liebherr in Germany became two of the best-known names, and Italy developed a strong group of specialists.

Over the decades self-erecting cranes became taller, stronger and easier to operate. Radio remote controls let one person operate the crane from the ground or the building, hydraulic erection systems replaced much of the manual work, and electronic controls made erection sequences safer and faster. Truck-mounted versions, which combine the crane and its transport vehicle, added another option for short jobs.

How a Self-Erecting Tower Crane Works

Base and ballast. The crane stands on a chassis with four outriggers, which are levelled and loaded with ballast blocks to stabilise it.
Mast. The mast is made of telescoping or folding sections. During erection it rises from its transport position and locks in the vertical position.
Jib. The jib is folded in two or more sections for transport. It unfolds as the mast is raised and can often be set horizontal or raised at an angle to clear obstacles.
Slewing. Unlike most large tower cranes, many self-erecting cranes slew at the bottom: the whole mast rotates on a slewing ring at the base, with the counterweight on the rotating platform.
Hoisting and trolleying. Winches raise the hook and move the trolley along the jib. The crane is usually operated by radio remote control, and some models also offer a cab.
Power. Most self-erecting cranes run on electric power from the site supply or a generator, which keeps them quiet and emission-free at the point of use.

Types of Self-Erecting Tower Cranes

Fixed Self-Erecting Cranes

The classic design, delivered to site on its own axles or on a truck and erected on its outriggers. It stays in place for the duration of the job.

Truck-Mounted Self-Erecting Cranes

A crane mounted permanently on a multi-axle truck. It drives to site, sets up on the truck’s outriggers and can be ready to work within a short time. These cranes are often used for short jobs, from a day to a few weeks, and are hired with an operator.

Compact and Mini Self-Erecting Cranes

Small models with short jibs and low capacity, designed for private houses, gardens and restricted sites where every metre of space counts.

Large Self-Erecting Cranes

The biggest models approach the performance of small top-slewing cranes, with longer jibs and higher hook heights, and they can serve larger residential and commercial buildings.

Size Classes

Class	Typical jib length	Typical maximum capacity
Compact	about 20 to 30 m	about 1 to 2 t
Medium	about 30 to 40 m	about 2 to 4 t
Large	about 40 to 50 m and more	about 4 to 8 t

Figures are indicative. Maximum capacity applies close to the mast. At the tip of the jib, capacity is much lower, often around 1 t or less.

Main Manufacturers

Potain (Manitowoc), with the Igo and Hup ranges.
Liebherr, with its K-series and other fast-erecting cranes.
Spierings, the Dutch specialist in truck-mounted self-erecting cranes.
Italian manufacturers such as Vicario, Cattaneo and Edilmac.
Comedil is another name found on many sites, especially on older cranes.

Main Uses

Single-family houses, terraced houses and small apartment blocks.
Renovation and extension work in town centres.
Agricultural and light industrial buildings.
Roofing, precast and masonry work where materials must be placed at height.
Short lifting jobs, often with truck-mounted cranes, such as installing roof trusses, air conditioning units or glass.

Self-Erecting Crane or Mobile Crane?

A mobile crane is ideal for a single heavy lift or a job lasting a few hours. A self-erecting tower crane is more economical when the crane is needed every day for weeks or months, because it has a lower running cost and takes up less space on site. It also offers a long horizontal reach at a low height, which suits placing materials across a building. For jobs in between, a truck-mounted self-erecting crane combines some advantages of both.

Planning a Self-Erecting Crane

Ground and position. The outriggers need firm, level ground. The position should allow the jib to reach all delivery and placing points.
Space to erect. The crane needs space to unfold and a clear zone free of overhead power lines, trees and buildings.
Power supply. Check that the site supply matches the crane’s requirements, or plan a generator.
Out of service. When not in use, the crane must be left free to weathervane, turning with the wind, and its jib must be able to rotate without hitting anything.
Permits. Oversailing neighbouring properties or public roads may require agreements or permits.

Hiring or Buying

Many self-erecting cranes are rented, often with delivery, erection and dismantling included, because a small builder may need a crane only for part of the year. Contractors who build houses continuously tend to own their cranes, since a self-erecting crane can move from one site to the next many times a year. When comparing models, the key figures are the capacity at the tip of the jib, the hook height, the space needed to erect the crane and its transport dimensions. The capacity at maximum radius usually matters more than the headline capacity close to the mast, because the heaviest loads rarely need to be placed right next to the crane.

Safety

Self-erecting cranes are easy to operate, which makes training and procedures even more important. Operators must follow the load chart, respect wind limits and never exceed the capacity at the working radius. Remote control operation requires a clear view of the load or a signaller. The erection and dismantling sequence must follow the manufacturer’s instructions, since most serious incidents with this type of crane happen during these phases or because of poor ground conditions under the outriggers. Regular inspections of wire ropes, brakes and safety devices are required in most countries.

Trends and Technology

Manufacturers are working on longer reach and higher capacity in the same transport dimensions, faster and more automated erection, and better remote controls with displays that show load, radius and wind speed. Battery packs and hybrid power systems allow some self-erecting cranes to work with a limited site power supply, and connectivity lets rental companies monitor use and maintenance remotely.

Key Terms

Bottom slewing: the whole mast rotates at its base, typical of self-erecting cranes.
Top slewing: only the upper part rotates on top of a fixed mast, typical of large tower cranes.
Ballast: blocks placed on the base to stabilise the crane.
Weathervaning: leaving the crane free to turn with the wind when not in use.
Hook height: the maximum height of the hook below the jib.

Frequently Asked Questions

How long does it take to erect a self-erecting crane? Depending on the model and the site, from under an hour for some truck-mounted cranes to a few hours for larger fixed models.

Does a self-erecting crane need a crane operator’s licence? Rules vary by country. In most places, operators need specific training and certification for the type of crane they use.

Can a self-erecting crane be installed on a building? Normally it stands on the ground on its outriggers. Installation on a slab or structure requires an engineering check of the loads.

What is the difference between a self-erecting crane and a top-slewing tower crane? A self-erecting crane unfolds itself and usually slews at the base. A top-slewing crane is assembled piece by piece with a mobile crane, is much taller and stronger and is used on larger buildings.

Can a self-erecting crane work in the wind? Only within the wind limits set by the manufacturer. Above those limits, lifting must stop and the crane is left free to weathervane.