The mobile folding tower crane has been popular in the Netherlands for several years but now there are signs of the concept gaining popularity further afield. JB Heystek, managing director of Mobile Tower Cranes (formerly GIS Munsters), puts the Dutch market at between 40 and 50 units a year. Until a year or so ago, that was it. But interest is now growing elsewhere, in Germany in particular but also the UK, and Heystek estimates that annual demand will soon be between 100 and 200 units.
Two Dutch manufacturers, Spierings Kranen and Mobile Tower Cranes (MTC), had little if any competition until the mighty Liebherr entered the fray in 1998. Whether Liebherr has helped grow the market or has simply responded to demand that Spierings and MTC did not have the capacity to satisfy alone, is not clear.
Familiar names in the German crane rental market, as well as construction companies, are beginning to put truck-mounted tower cranes in their fleets. Wiesbauer has a four-axle and a five-axle Spierings, while Scholpp and Armbruster have gone for Liebherr’s MK 80. Dutch rental company BKF also does jobs in Germany and runs Spierings cranes.
To April 2001 more than 20 Liebherr MK 80s had been delivered and total orders numbered more than 40 units. Most of these are to Dutch crane rental and construction companies but about 20% of the orders are from elsewhere in Europe, including five units to Germany, two to the UK (to lifting contractor Commhoist) and one to Italy. Depending on performance and reliability of the MK 80s, Commhoist managing director Bob Kerslake says he would consider buying more units. He is also looking at Spierings’ models.
Spierings launched its latest model, the SK 488-AT4, in August 2000 and within eight months 23 units had been delivered. One went to Belgium and five to Germany. Another German order had yet to be fulfilled. Spierings’ UK distributor Kato UK has sold three units of this type of crane – John Glover of Northern Ireland is to take delivery of a new SK 488-AT4 and a new SK 598-AT5 later this year, and City Lifting near London has bought a used Spierings three-axle model. Kato UK is also getting a three-axle unit for demonstration to potential customers.
New from MTC this year is a new three axle model, the Munsters ABK 35-70. It was introduced in January and by early May MTC had delivered four units. Manufacturing capacity is currently about 15 units a year but this is set to increase in the near future, according to the company.
There seems little doubt that Spierings is currently the most productive of the three manufacturers. And this year’s Bauma construction equipment exhibition in Germany generated many more new sales leads for Spierings, including some strong interest from Switzerland. says founder/ owner/general manager Leo Spierings.
Spierings says of Liebherr’s introduction and promotion of its MK 80 that ‘it helps us a lot, it means better opportunities’. It raises the profile of the concept and raises awareness of its potential, he says.
Heystek agrees: ‘We think that the introduction of Liebherr in this market will help to break through in other countries. So it may cost some orders at the moment but in the long term it will only help to develop and increase other markets.’
Spierings has three models in its range: the three-axle SK 365-AT3; four-axle SK 488-AT4; and five-axle SK 598-AT5. The SK 488-AT4 was launched in August 2000 as a replacement for the SK 477-AT4. The difference is that the new model has a closed, tubular section tower instead of an open lattice design. The three-axle model is lattice, and the five-axle is closed.
The carrier of the SK 488 is more like that of an all-terrain crane than the old model, Spierings says. It has Ginaf axles and is designed to run on large diameter tyres to give better off-highway performance. As standard it runs 445×75 tyres instead of the 445x65s that were on the old model it replaces. Axles two, three and four are driven on the SK 488 and three axles are also driven on the five-axle SK 598-AT5 but on the larger model there is also the option of having the front axle driven hydrostatically.
Liebherr has produced truck-mounted towers in the past but in the last couple of years it has given a new push to its efforts. The MK 45 was launched in 1998 and about 50 units have since been sold. Mounted on a commercial four-axle truck chassis-cab, it lifts 1.5t at 27m reach and 17.7m hook height. Liebherr’s latest take on the concept, the MK 80, was shown in prototype form last May at the Intermat exhibition in Paris and made its German debut at Bauma this year.
The MK 80 differs from the MK 45 in that it is mounted on a purpose-built carrier made at Ehingen where the all-terrain cranes are manufactured. It combines the mobility of an AT with the functions of an 80tm self-erecting tower crane with fast and simple assembly by one person, Liebherr says. It travels on a four-axle (three driven) chassis with hydro-pneumatic suspension and is powered by a 270kW Liebherr diesel engine.
The telescopic tower mounted on the slewing platform is a lattice structure, with close-welded square-section uprights and diagonal struts. At a 42m jib length and a 30° inclined jib position with 48.1m hook height, the MK 80 lifts a maximum of 1,700kg at the jib head. Maximum load capacity is 8t.
The MK 80 goes head to head with Spierings’ latest model, the four-axle SK 488 launched last August, which lifts 2.1t at the maximum 40m jib length.
Leo Spierings describes the MK 80 as having a conventional tower crane structure whereas his SK 488 model, and the larger five-axle model, have a closed, tubular tower structure. This is designed to be more stable. It takes 15 minutes to erect – half the time of the MK 80, Spierings claims. At the Bauma exhibition Liebherr erected its MK 80 in 13 minutes, according to a customer who bought two units.
Spierings says that operators prefer the closed structure to towers that use a conventional lattice design. The closed tower design is similar in weight to a lattice tower but more expensive, Spierings claims.
The completely electro-hydraulic erection system on Spierings cranes contributes to the erection time advantage and means higher productivity over the Liebherr, which uses a cable erection system, according to Spierings. Spierings has a remote control unit for erection that can also be used to operate the crane. His three-pump (a separate one for each motion) electro-hydraulic system gives higher hoisting and slewing speeds than the Liebher but trolley speeds are similar, he claims.
Both the Liebherr and the Spierings have on board diesel generators but the Spierings crane can be plugged in to run on site power instead of from its own generator.
Delivery time is Spierings’ problem, he says – it is longer than Liebherr’s. He opened a new factory last August and has increased the workforce from 53 to 92 and is still looking for more people. Annual production is running at about 50 units a year, or one unit every four days, but Spierings wants to increase that to two units a week. By the end of April 2001, a total of 241 Spierings cranes had been delivered since the first prototype appeared in 1989.
Following on from the MK 80, Liebherr has already taken orders for its forthcoming five-axle MK 120, which features a 38m mast and 52m jib. Dutch rental company Riwal (which has taken delivery of the first of three MK 80s) has ordered two MK 120s, for delivery towards the end of next year, and has an option for a third.
What applications they are good for
The truck-mounted self-erecting tower crane is variously described as a folding crane, a mobile tower crane, and a mobile construction crane. Increased productivity by completing jobs in less time is a primary advantage, according to manufacturer Leo Spierings. He says that some jobs can be done in four or five hours that would otherwise take up to eight hours with a telescopic boom all-terrain crane, which can translate into an extra couple of jobs a day.
JB Heystek, managing director of Mobile Tower Cranes (MTC), attributes success of this type of crane in the Dutch market to construction methods, the ability to operate on confined sites, faster working and good returns on investment.
Crane rental companies see mobile tower cranes as better and more reliable than all-terrain mobiles, according to Leo Spierings, and they are ideal for jobs where a crane is needed for between about half a day and two days at a time. They are particularly useful for reaching up and over tall buildings or other obstructions to place loads. Many customers are familiar with tower cranes but when these are not mobile enough the folding mobile tower crane can be the solution.
Paul Rosevere, sales director at Kato UK which sells Spierings cranes in the UK, says the three-axle Spierings model can be used as a general jobbing crane, as an alternative to a 25t truck crane with a fly jib. Erection time is about the same as a truck crane without a fly jib, he says, and quicker if the truck crane needs to be rigged with a fly jib.
Heystek says his mobile tower cranes can take market share from hydraulic cranes of up to 70t capacity. Spierings claims that his cranes can be used instead of ATs of as much as 150t capacity. The five-axle model covers the top end of the range from about 150t down to 120t mobiles, the four-axle down from this to 80t, and the three-axle below that.
Prices are competitive too, according to Spierings. He says that his five-axle model is between 10% and 20% cheaper than a 150t AT, or about the same price as a 120 tonner.
