Counterbalance Valves - / Ruppel Group

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DIN ISO 9001:2015DIN EN ISO 9001:2015

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Counterbalance Valves

Over-centre valves with three connections from SUN are proportionally controlling valves with free discharge in one direction
at connection 3. In the reverse direction, the valves are closed, until
a proportional control pressure - reversed into a load pressure - is applied (the higher the load pressure, the lower the control pressure needed for opening). The valves function as a non-return valve for free discharge in one direction, and as pressure relief valve in the other direction. With increasing control pressure on the third connection, the set value for the pressure limit decreases. Most of the valves have thermal protection.

Loads can be lowered or checked in a controlled manner, in case
a directional control valve is used in open centre position.

Aided by over-centre valves, all drives are controlled better, since - for the directional control valve - these loads become positive loads, even when the load itself pulls on the engine (negative load). Due to the reversed control ratio, small loads are lowered with high control pressures and high loads with smaller control pressures: in this way, the loads can be controlled better and the stability of the entire drive is improved.

With over-centre valves, negative, pulling loads become - from the perspective of the directional control valves - positive loads. As a result, motion control becomes considerably more easy. Over-centre valves from SUN with three connections, have the following characteristics:

  • Limited degree of leakage when closing. When the load pressure amounts to 85% of the opening pressure, the leakage of new valves will be max. 0,35 cm3/minute. Using the valves in systems with peak loads or impurities can result in wear and tear of the gaskets. In this case, systematical replacement programs are in place.
  • High tolerance against oil contamination.
  • Stable and reliable operation, with hot as well as with cold oil.
  • Operating pressure up to 350 bar.
  • Discharge range up to 480 l/min.
  • Available with a control ratio of 3:1 AM, 4.5:1 AM or 10:1 AM.
  • The opening pressure of the valve can be set with an adjustment screw. In this way, loads can be released manually in case of emergency, when the control pressure has failed.
  • The integrated non-return valve is available with various pressure settings (2 bar is recommended for protection against peak loads, whereas 3 bar is recommended for protection against cavitations).
  • The majority of valves have a limited amount of leakage behind the control pistons. This leakage is intended; it facilitates bleeding of the controls, resulting in improvement of the stability of the hydraulic drive. In some valves, sealed control pistons are standard.

Cartridges / screw-in valves (application example: floating dredger)

Cartridges / screw-in valves
(application example: floating dredger)

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