Easing work on site ... the Rollerlift.
Hydraulic lift eases formwork placment
01 December 2001
When working on projects, BAM Woningbouw of The Netherlands uses a device for lifting and placing steel tunnel formwork that is said to be as unique as it is simple.
The device is called the Rollerlift and it is enabling the builder, which specialises in residential construction, to make extremely accurate horizontal and vertical adjustments to heavy steel formwork with care, says the device's developer, Enerpac of the US.
"Steel tunnel formwork for pouring concrete walls and floors has been used in the construction of homes for some 25 years," says an Enerpac spokesman. "It's an extremely efficient construction method, in which complete 10 x 5 m concrete frames for houses can be poured in a single operation. After the concrete has set and dried, the tunnel formwork is removed the following day and then laid down at the next pouring site."
"In the early years, tunnel formwork consisted of separate elements which were joined together to form a unit before the pouring; these could be put into position and removed manually. Nowadays, however, complete tunnels are used which can be moved with a crane. But there's still one big problem: accurately placing the 5-6 tonne tunnel formwork before pouring the concrete and removing, or sliding it out, afterwards. Down the years, various methods have been developed to deal with this problem, including rack jacks, winches and rollers.
"BAM Woningbouw has been using loose rollers and an electric winch for some time to get the tunnel element to 'ride' out of the poured concrete. For the height adjustments, a rack jack was used in addition to the crane. For the horizontal adjustments against the keyway, however, a crowbar was used. The result was that the feet of the rack jack would, in the course of time, become crooked, which made it difficult to wind up.
"To solve this problem, two years ago BAM Woningbouw developed a device with which the tunnel formwork could not only be adjusted vertically but could also be easily pushed horizontally against the keyway. The device consisted of a single articulated jack with two rollers which could slide 4 cm on one axis. A solution which, alas, turned out not to be durable enough, as the bearings were not resistant to the tunnel weight of 5 to 6 tonnes."
"From a mechanical point of view we couldn't accommodate the forces arising and the required height in one device," says BAM Woningbouw's Harry Bouwhuis. "So we looked for another way of doing it, and hydraulics seemed to be the only suitable technique."
Using the original idea as a basis, Enerpac came up with a perfect solution and developed, especially for BAM Woningbouw, the three-dimensional hydraulic Rollerlift.
The device consists of a frame containing a standard hydraulic cylinder which operates two levers with hard plastic rollers. The rollers are mounted on a pivot in such a way that they are free to slide.
"This arrangement maintains the basic idea of the two rollers: the lifting function and the possibility of making a sideways movement," says Bouwhuis. "The structure just has a much heavier design and now has a load-bearing capacity of as much as 14 tonnes at a lifting height of 190 mm."
The reason that BAM Woningbouw chose Enerpac was that the Rollerlift emerged as the most efficient construction in a series of tests. "We did consult with Enerpac about some adaptations but, with the Rollerlift, placement and keeping are much easier," comments Bouwhuis.
"The most important advantage of the hydraulic Rollerlift, however, is that the tunnel formwork can be placed much more accurately than has previously been the case thanks to the use of hydraulics and the fact that the rollers can slide horizontally," says Enerpac's spokesman. "An automatic balancing effect arises."
Says Bouwhuis: "The accuracy requirements have become increasingly stringent over the past few years, so this is a perfect solution in that respect. And now we can move the formwork both horizontally and vertically much more easily and therefore much more quickly."
But apart from increased accuracy, Bouwhuis can name other important advantages of the hydraulic Rollerlift. "The lateral connection to the keyway is optimum, there's less lateral load from the equipment and with the 14-tonne load-bearing capacity there's plenty to spare.
''An additional advantage from the point of view of health and safety at work is that the 72-kg Rollerlift is permanently attached to the tunnel formwork. That means that there's no longer any need to shift heavy weights," he says.
"In addition, the hydraulic Rollerlift also has a durable construction. It's been designed so that the hydraulic cylinder is only loaded linearly and is therefore not subject to lateral forces. The bearing roller/pivot construction has an exceptionally strong construction and the roller slides so easily backwards and forwards over the pivot that there's hardly any wear here too."
Enerpac has manufactured a total of 120 Rollerlifts for BAM Woningbouw. And although, generally speaking, concrete and oil are generally not a successful combination, the high-quality, reliable and safe hydraulic components mean that there are now no longer any problems, the spokesman says.
Enerpac is a leading manufacturer of hydraulic tooling and parts for a range of manufacturing and assembly sectors. The company's products have been specifically designed to meeting the requirements of extra productivity, top quality and safety.
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