Three Stage Servo Valves
BIA West has developed a range of three stage servovalves from 100gpm (380l/min) to 1300gpm (5000l/min). The challenge with any servovalve is to minimize crossover distortion. This is caused by the hydraulic switching that occurs as the valve spool travels through its midstroke (nul) position, and switches flow from one port to the other. There is a critical time at the center, when flow is completely blocked. Since this would create very high pressure spikes in the manifold, this effect must be minimized, and so valves are usually overlapped, or underlapped with leakage that creates non-linearities. BIA West has developed a manufacturing techique that allows us to closely control the very tight tolerances required to build a valve with linear performance through this switching band, maintaining a smooth and proportional velocity transition through zero. Our valves also lead the industry with very low pressure drop and leakage.