HydraForce Insider Blog

Here at HydraForce our Technical Services department typically receives multiple question daily regarding our Proportional Valves.  Common questions include, "What is the proper dither frequency for a particular proportional valve?' and "What coil should I use with this type of system?".  Following these five simple rules when applying  proportional valves  will prevent field failures, reduce valve instability, and ensure that your system performs as desired without having to reach out to a tech service representative.

1. Applying dither to a valve reduces actuator friction and reduces hysteresis.  A good rule of thumb is to use 70 -250 Hz dither frequency on all SP, ZL, and PV valves (flow and directional control valves), and 200-300 Hz dither frequency on TS Valves (proportional pressure control valves). Otherwise, at lower frequencies the actuator will follow the dither signal and the valve output will appear unstable.

The idea to develop Multifunction Valves came from our engineers noticing that particular combinations of valves were used over and over again in standard hydraulic circuits.  For example, a 2-way, 2-position SP proportional valve is typically paired with a pressure compensator to provide pressure compensated flow control.  This particular example drove the development of the PV Proportional Flow Control family of valves, which include the flow control and pressure compensator inside the same cartridge.  There are many other multi-function options, including the SPCL, SVCL, SVRV, EPFR, FRRV, and others).

The orifice is one of the most versatile components that we can add in our hydraulic circuit. The orifice can be used to limit the amount of oil in one part of our system, to bleed a pressure line to tank, or to transform a nervous and aggressive circuit into an efficient and highly controlled one. Often times the orifice has to simultaneously manage a very small amount of oil, control a dynamic flow rate and dump a system’s compensator. In many applications -- especially for hydrostatic transmissions -- it is important to control the dynamic pressure of the system to avoid pressure spikes and pressure ripple.