The use of valves that control pressure proportional to an input signal, is an effective solution to the problem of providing ever more subtle and fine control demanded by the end user, according to Integrated Hydraulics. The company added that striving to improve controllability is driven by the need for continued improvements in productivity and safety, so Integrated Hydraulics has designed a new pressure reducing cartridge valve that is said to be simple but effective and accurate. Typical applications for the cartridge valve will be provide a proportional pilot pressure to a directional valve or transmission, raising or lowering of a sweeper brush, or cooling fan control circuits.

The proportional pressure reducing valve, designated PPD2 2 is of simple, robust, spool type design and makes use of tried and tested components and technology.

With no current applied, the regulated port is connected to tank.

As the current increases the pressure in the regulated port will rise to balance the increasing solenoid force.

Pressure in the regulated port acts on the spool tending to close it against the force of the solenoid.

As pressure in the regulated port increases (with a constant current applied to the solenoid) the spool will shift, restricting the inlet, equilibrium is then achieved and a reduced constant outlet pressure held.

Varying the current will alter the force applied to the spool and hence the pressure in the regulated line.

The cartridge has a maximum inlet pressure of 210bar and a maximum regulated pressure of 28bar (when fitted with a 29 watt coil).

It benefits from having no dynamic seals, reducing hysterisis and prolonging service life.

The armature is oil immersed and the coil and stem sealed to avoid atmospheric corrosion.

A manual override is provided to help set-up and to operate the valve in the event of power failure.

PWM (Pulse Width Modulation) is preferred with a frequency of 200Hz to minimise the hysterisis.

The coil is interchangeable with those used on their S5 Series valves, reducing spares inventory.

It uses the same cavity as other valves in the pressure reducing valve range, so no new tooling is required.

Due to excellent design and close manufacturing tolerances, internal leakage is minimal at 50ml per minute at 210bar pressure differential.