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Press releases
Rack and pinion jacks move a climbing formwork
haacon's robust Rack and pinion jacks are used to cyclically move formwork sections. The example shows the new cooling tower of the Ledvice lignite power station near the Czech town of Bilin. The power station, which was built between 1966 and 1969, is currently being expanded with an additional block offering an output of 660 MW. When it is finally completed, the additional cooling tower which is required will reach a height of 140 m. Staff of haacon hebetechnik gmbh were on the construction site and were able to gain their own impression of operating conditions at these dizzy heights.
A series of climbing work platforms, visible from far away, encases the top edge of the hyperbolic-shaped concrete cylinder. Each climbing work platform follows its own vertical surface line from the bottom to the top. Each formwork panel is planar. However, since each individual element is proportionally small compared to the large diameter of the whole, the structure appears entirely round. The footprint is a polygon with 50 corners. The variation in diameter is handled by adjusting the width of the formwork panels used, and the vertical gradient can be adjusted via spindles. A formwork lifting platform weighs a substantial amount - almost 7 tonnes. Every 3-4 days, the formwork inside and outside the tower moves up a maximum of 1800 mm.
Why do we use Rack and pinion jacks?
For building site applications, only rigid materials can be considered.
For many years, formwork manufacturer Doka / Umdasch has successfully deployed rack and pinion drives for moving formwork elements at great heights on projects around the world.
The racks, which are milled from a single piece and then hardened, stand out for being impermeable to dirt and dust and being easy to use. Synchronisation of the individual elements with the hydraulic drives is simple to achieve.
They can also be motor-driven at low speeds up to 60 rpm and for intermittent operation. A corresponding gear motor is mounted in a bracket with a form fit. The servo drive and winch are perfectly aligned with one another. Using a manual control, the concrete worker can move the entire platform to the desired position, where it is again anchored to the structure. A brake head on the winch holds the load securely in each position. In our case study, a total of 100 of our basic model 1624.10 Rack and pinion jacks, each approved for a load of 10 t, are being used.