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APPLICATION FORKLIFT
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.
FUNCTION
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.
COMPONENTS
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
QNPPM33
• 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.
SPECIALITIES
• With heavy loads, the system can tend to oscillate (bouncing effect), this can be absorbed and corrected with internal valve
adaptions.
• 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