For an art exhibit by Anish Kapoor in Berlin last year, a 24t sculpture made of 8mm Cor- Ten steel skin needed to be assembled. Each piece weighed from 1–2.2t. The artwork was being installed in an enclosed room of the Guggenheim museum. Two Maeda MC 285 mini cranes with electric motors were the solution. Small enough to access the display area and capable of lifting up to 2.82t, they built the sculpture with minimal noise and pollution.
While mini cranes (also referred to as spider or compact cranes) are still considered specialist equipment and dealers could only estimate around 350 exist in the UK, they’re being put to use across many industries. And end users are reporting some rather varied projects putting them to use. New mini cranes are being introduced to meet the increasing interest, including Valla’s 25 E, Kegiom Lifting’s Model 200 Panda, Jekko’s SPX 1040 and Galizia’s GK20.
Curtain walling, glazing and steel erection is still the main sectors using mini cranes, and they are becoming popular in the slip form industry, too. With their compact size they’re ideal for projects with confined spaces, or floors unable to support a lot of weight, such as the low-density concrete floors of high-rise towers that require low point loadings. Distributors have seen mini cranes being hired or purchased by individual contractors to use on building sites rather than vying for time on the site’s main tower crane.
Working on the St Botolphs high-rise office development in central London, steel contractors CMF Ltd decided to use three modified Unic 706 mini cranes to install the building’s stairwell towers. The site’s tower crane lifted the mini cranes to the top of the four towers and they were secured in place by special sockets designed to hold the feet of the outriggers. Remote controls were used to operate the cranes, which erected the steel support framework for the stairwells.
“They’re not a replacement for a tower crane,” says Graeme Riley, CEO of GGR Group, which distributes the Unic brand. By having their own small crane, contractors don’t have to wait around for the tower crane, and can make themselves more self-sufficient, he explains. For example, these cranes could be up on the roof or indoors installing glass on a building’s façade, like the St Botolph project. Glaziers can put a mini crane on one floor, extend the boom over the side of the building and lift glass units from below.
Using a compact crane on site can be cheaper as well, points out Carl Cooper, sales manager at Compact Lifting Equipment, who deals mainly with 2t pick-and-carry cranes. It saves money on manpower compared to a tower crane that requires at least an operator, Banks man and lift supervisor. “You will need less people if you have a pick-and carry crane doing the job, and if you have less people on the job, you have less risk of accidents,” Cooper says.
Another sector where mini cranes are also gaining interest is in factories and with facilities managers. Thomsonfly, for example, bought a 6t Unic 706 in 2008 to service aircraft at its maintenance deports at Luton Airport. Their compact size allows them to replace forklifts when it’s necessary to lift and to transport loads that aren’t on pallets or when a forklift’s tines are unable to access a load due to obstacles.
While Cooper says more and more people are looking into pick-and-carry cranes, there is a tendency to fall back on telehandlers or other equipment. “You’re always going to get people who will say ‘I can put something on the tines of a forklift and use it as a crane,’” he says. The problem with that mindset, Cooper says, is that telehandlers and forklifts don’t have the same safety features as cranes. Mini cranes have safety functions like mobile and tower cranes, so they can be used in any lifting environment. They have computer systems that judge whether the crane can lift the load. Forklifts don’t have that and telehandlers have only basic systems, he explains. But most of the hesitancy relates to the price tag.
“Companies are realizing that this is the type of equipment they should be using and want to use,” he says. “It was growing quite significantly but I think with this recession it’s hard to tell where we are.” Other dealers echoed the same sentiment that the economic downturn during 2009 made it hard to judge how quickly interest is growing for mini cranes.
Riley says he has noticed that, rather than rental companies, it tends to be the end users buying these cranes. Councils and glass companies are examples of people who had been hiring cranes, did the math and decided to buy their own smaller compact crane, which they can often transport on their own vehicles.
Another advantage mini cranes have over larger cranes is electric and LPG power options. This, paired with their size, makes them ideal for working indoors, like at the Guggenheim, and on projects where petrol would be dangerous. Mini cranes are being used in shopping centers, airports, residences, leisure property and museum projects to name a few, and not just for lifting glass or steel erection.
Last summer, artist Roxy Paine installed a 130 x 45ft stainless steel outdoor sculpture on the rooftop of the Metropolitan Museum of Art in New York. To get approval for the project from the New York City Fire Department, no machines using petrol or propane could be used, says Keith Shank of C4 Cranes in Minneapolis, Minnesota, which supplied two Jekko battery-operated SPD360C+ mini cranes to erect the sculpture. Batteries were the only power option approved of because in the event of a problem there is no way to put a fire out up on the roof, Shank explained.
Another benefit of using mini cranes on this project was that they avoided the need to position a larger crane in the crowded Manhattan streets for the duration of the installation. Instead, a mobile crane was used to lift the artwork’s separate pieces and the two 2,200kg mini cranes onto the roof. One crane held the sculpture as Paine and his team worked and the second, equipped with a man basket, lifted him around the structure to weld everything together.
Alternative power sources mean a smaller carbon footprint with a mini crane, which was appealing for projects at Masdar City in Abu Dhabi, billed as the world’s first carbon neutral and zero waste city. John Corrie, equipment operations manager of Instant Access in the UAE, has supplied Maeda mini cranes with LPG options for customers at Masdar who need to minimize emissions.
The strict requirements of Masdar are rare, Corrie says. Most people chose compact cranes for their small size and low point loadings on the outriggers. Like in the fairytale Park Hotel Vitznau in Switzerland, built in decorative Belle Epoch style in 1903. It closed its doors in autumn 2009 for an extensive two-year renovation, bringing in Nello’s Repair Service to take down its antique chandeliers.
Ruth Hodel, in charge of marketing and finance for Nello’s, explains that Switzerland’s many old buildings are often made out of easily damaged materials such as brick, sandstone and wood. “If you work in an old building, you have to be very careful with the machinery you use, because of the weight. Mostly there are no existing plans or calculations of ground pressure that can be allowed,” she says.
Evaluating the accessibility of the hotel, the ceiling height and the weight of the chandeliers, not to mention the aged and wobbly wooden floors, a Maeda MC 104 CER was chosen for the delicate job. Measuring just 60cm wide, the MC 104 CER could pass through all the necessary doors, and its electric 400V motor kept the pollution and noise levels to a minimum. Though the mini crane only weighed 950kg, to minimize the ground pressure, the floor was covered with metal sheets before the crane was installed. It was placed within the room in places where pillars or walls below could provide support.
For a separate project in September, Nello’s used an MC305 CRM-E to lift parts of an organ being rebuilt in Switzerland’s Cloister of Bellelay, which dates back some 600 years. Organ parts weighed up to 300kg and need to be lifted 15m and over a banister. To do this, a fly jib was attached. The MC305’s 3,900kg weight was the maximum the tile covered floor could support.
Accessibility is one of the main drivers behind the popularity of mini cranes, including isolated environments, not just small doorways and delicate flooring. It is possible to strip down the crane, take the boom off and remove the outriggers and fly them in, Riley explains. GGR Group supplied URW 376 cranes to construct a biological and meteorological research centre on Marion Island, nearly 1,800km off the South African coast. The cranes were flown to the island via helicopter.
In a separate project in December, a steel manufacturing company using a diesel powered Jekko SPD260CD/M equipped with a 600kg winch and 60m anti twist rope performed maintenance and steel erection on a 60m-tall double arch dam. From the top walkway, the crane operator used wireless radio remote control to lower steel stairs, doors and ice shields, the heaviest parts weighing about 300kg.
From crowded urban construction projects, to the tight squeeze of precious indoor spaces and the inaccessibility of rugged environments, mini cranes are often going where no crane has gone before.
