Structure and application areas
Telescopic cylinders are a special type of hydraulic cylinder that enable a long stroke length in a compact installation situation thanks to several interlocking piston stages. They consist of several cylinder tubes of different diameters, which can be extended like the segments of a telescope. This design makes them ideal for applications with limited installation space and high stroke requirements.
Due to their design, telescopic cylinders are used in numerous industries:
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Foundry industry
Precise control of the tilting movement of a mould (casting mould)
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Commercial vehicles and construction machinery
Tipping devices for lorries, wheel loaders or dumpers
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Presses and recycling plants
Compact design with high power transmission
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Lifting platforms and crane technology
Extended strokes allow maximum flexibility in use.
Specialities and challenges
Telescopic cylinders have to transmit high forces, while at the same time each stage requires precise guidance to prevent wear and mechanical damage. The following challenges arise in particular:
Precise manufacturing: The individual piston stages must be precisely aligned with their running surfaces in order to minimise friction. This requires exact internal machining (honing).
Sealing systems: The stages must be fitted with optimally adapted seals to minimise leakage.
Lateral forces: Telescopic cylinders are primarily designed for axial forces and react sensitively to lateral loads. These must be adequately taken into account in the design in order to avoid malfunctions or premature wear.
A telescopic cylinder in need of optimisation
A leading automotive supplier approached us with an acute problem:
A telescopic cylinder had failed and urgently needed to be analysed, optimised and repaired.
Analysis of the damage
After dismantling the defective cylinder, the inspection revealed that improper contact of the sliding surfaces, increased abrasion on the running surfaces and heavily worn seals had occurred during operation. In discussions with the customer, we established that considerable lateral forces acting on the individual steps had caused this condition. The existing guides and seals were not designed for these loads. This led to the piston tubes rubbing against each other, which ultimately resulted in the cylinder failing.
Engineering solution from ACONA
In order to eliminate the structural problems of the cylinder, we developed specific modifications:
Additional guide element: Guide bands were integrated according to the load case in order to absorb lateral forces and optimally stabilise the individual stages in their axial direction.
Modified materials: To reduce wear on the contact surfaces between the cylinder stages, materials with good sliding properties were used and the material combinations of piston rod and cylinder were varied (e.g. use of cast materials).
Optimisation of the sealing technology: High-performance seals with improved friction properties were installed to ensure the smooth running of the cylinder and prevent the stages from jamming.
The result
After the modification, the revised telescopic cylinder was delivered back to the customer. The implementation of the new guide element absorbs the lateral forces, which means that the movement of the cylinder stages now runs smoothly. The modified cylinder is now back in use.
The customer was impressed by the fast and solution-orientated approach. The cylinder was optimised and repaired within a very short time.
This successful optimisation once again underlines our expertise in the development and reworking of hydraulic cylinders - especially in the field of sophisticated telescopic cylinder technology.
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