Industrial Vehicle Technology - June 2020
DON’T DROP THE PRESSURE
2020-07-10 04:58:45
From a certain size on, hydraulic systems require large volume flows with high pressures. Such efficient systems can be found in aluminium processing in the form of casting presses with holding pressure systems, in the opening mechanisms of large ship hatches, in large freight elevators, in cranes or in the braking systems of cable cars, not to mention the booms of concrete pumps. To be able to carry out all these large and heavy tasks at an efficient speed, correspondingly powerful valve technology that can be controlled precisely and sensitively despite the large capacities is required. Wandfluh has developed the 2-way slip-in cartridge valves for such tasks and has continuously improved their performance over the years.
The 2-way slip-in cartridge valves are inserted in the control block into a bore standardised according to ISO 7368 and closed with a control cover. In operation, they merely act as amplifiers, following the pilot valve on the cover that can be controlled manually or electrically via an analogue or digital interface. Combined with intelligent electronics, complex hydraulic circuits that are characterised by very high pressures and flows can thus be implemented within a hydraulic block.
The proven range of 2-way slip-in cartridge valves has been supplemented with significantly more powerful valves in the nominal sizes NG16, NG25, NG32, NG40 and NG50. The new series is characterised by a three-part construction and, thanks to optimised flow geometry, offers practically a doubling of the maximum possible flow rate, while still maintaining a very low pressure drop Delta P. The slip-in cartridge valves have also been given a higher pressure resistance and are now approved for operation up to a system pressure of 630 bar (9,000psi).
Due to these two aspects, it is now possible to plan much smaller hydraulic systems. This means that, compared to conventional valves, the next smaller valve can be used without compromising performance. This in turn leads to even lighter, more compact and more efficient hydraulic systems.
The new 2-way slip-in cartridge valves are available in the two basic executions switching and pressure function, and can be supplemented by spools with non-return function, damping nose and/or seal. The modular design of the individual valve parts and the use of suitable cover and pilot valve combinations allow a wide range of different functions. These include spool valves with start, stop and directional control, pressure reducing valves for pressure limitation, pressure relief, pressure sequence and discharge function or nonreturn valves (spool valves with nonreturn function).
With the new series from Wandluh, hydraulic logic modules with a system pressure of 630 bar and up to a maximum flow rate of 2,360 l/min (with a pressure drop of 5 bar) can be combined in one block to form a complex circuit while saving space and weight. Thanks to the low pressure drop, this type of circuit is very efficient and, compared to a conventional hydraulic solution, has few interfaces where leakage would be possible at all.
Fast set-up and precise control are the basic requirements for a concrete pump boom to withstand the demands on a construction site. At the same time, the seat-tight valves prevent the boom from sinking over time and causing accidents.
Author: Bruno Maier, valve development, Wandfluh AG
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DON’T DROP THE PRESSURE
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