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            High speed and safety are important aspects in the efficient lifting and lowering of heavy
            loads, especially for devices with a high lifiting height. The high lifting and lowering
            speed requires a soft acceleration and deceleration characteristic of the hydraulics to
            ensure precise and safe operation. All these properties can be adapted to the respective
            application by appropriate construction of the hydraulic valve.

          An electric  high mast  lifttruck  is a typical  example of  a
          hydraulic  lifting  and lowering application.  Lifting  is  usually
          performed directly via the built-in hydraulic pump, as the load
          counteracts the direction of movement. For a controllable and
          smooth  lowering  function,  appropriate  hydraulic  valves  are
          used that allow the oil to flow back into the tank in a controlled
          manner via a bypass. In simple systems, this task is performed
          by a classic poppet valve. For more complex applications with
          increased requirements, pressure compensated proportional
          valves or  pressure compensated flow controllers  are used.
          Due to the construction of the valve, the the lowering speed
          is kept  constant, independent of the load. In addition, these
          valves are also available in a seat tight execution. This ensures
          that the fork  remains  in  its  position  when deenergised and
          does not sink slowly due to leakage.

          Various valves are available for the lowering movement:
          •  Soft-switching poppet valve S2206-S1841
          •  Proportional throttle valves DNPPM22 (25LPM) and
           DNPPM33 (63LPM)
          •  Load compensated flow control valves QNPPM22 and
          •  Seattight flow control valves QSPPU10 and QSPPM33
           These All-In-One valves control the lowering speed
           independent of the load and are tight when deenergized.
           The fork remains in position.

          •  With heavy loads, the system can tend to oscillate (bouncing effect), this can be absorbed and corrected with internal valve
          •  For forklift trucks in explosion-hazard areas, valves in Ex d execution are available.
          •  Valves with integrated electronics and connection to fieldbus systems.
          •  Large valves in M42 execution can control flows up to 200 l/min.

          PAGE 2           |               WANDFLUH MOBILE    |        APPLICATION     |       FORKLIFT TRUCKS
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