These valves are a series of three- or four-way electrohydraulic servovalves (EHSVs) commonly used to control position, velocity, and force in a variety of hydraulic system, fuel system, and engine control applications. Driving aerospace hydraulic actuators or motors in closed-loop servosystems, the EHSVs provide flows to 10 GPM at 1000 psi drop across the valve. The first stage is driven by an efficient force motor that is balanced so that lateral accelerations have little effect on output flow.The electrohydraulic servovalves provide unparalleled performance due to the highly reliable jet-pipe first-stage and large second-stage spool design. The result is an exceptionally contamination-resistant, erosion-tolerant, and high-flow servovalve that's designed to last. With an ability to perform in a contaminated environment, the Parker EHSV allows particles as large as 208 microns (0.008") to pass through the first stage without difficulty.Because the first-stage fluid impinges on a receiver that is fixed to the second stage, the Jet-Pipe® motor has low first-stage noise. The integrity of the projector jet stream results in optimum hydraulic efficiency (first-stage pressure/flow recovery) and better dynamic performance at low fluid temperatures.The motor armature is mechanically supported and balanced in all three axes, reducing the effects of vibration up to 2000 Hz as compared to our competition’s designs. Welded construction results in lower null shifts throughout temperature, pressure, and vibration extremes. The Jet‑Pipe design has an excellent first-stage pressure recovery, over 75 percent and typically approaching 85 percent of supply pressure, giving large second-stage chip shearing capabilities.Very high first-stage pressure gains, typically over 124 bars/mA (for 8-mA-rated current and 206-bars supply pressure) are realized due to the Jet‑Pipe design, resulting in excellent threshold characteristics. Erosion effects on the receiver dam do not increase quiescent leakage or significantly reduce the pressure-recovery capability of the first stage, assuring minimal reductions in first-stage performance. The torque motor area is dry, which protects the magnetic portion of the torque motor from contamination.Parker Aerospace Jet-Pipe servo technology offers proven, unsurpassed reliability and control that will operate in extreme environments. Our EHSV products are flying on most of the leading commercial and military aircraft in service today. OPTIONAL FEATURES:• Passes 200 or 500 micron through both stages• Hysteresis four or five percent maximum for input signals• First-stage screen of 90 or 2500 microns• Consistent dynamics up to 25 or 50 percent of full flow Features of the model 410 servovalveReliability – The model 410 Jet-Pipe servovalve has a single inlet first stage, making it a fail-to-center design. There is no risk of unbalance from contamination because there is only a single source of fluid for the first stage. Our second-stage spool design is capable of generating more than 100 pounds of chip shear force (with a nominal 3,000 psi system).Contamination resistance – Unique jet construction enables most designs to receive and pass particles as large as 200 microns without malfunction.Low sensitivity to vibration and shock – First stage is balanced and supported along all three axes against the effects of lateral acceleration and vibration. Acceleration and vibration tests show almost no effect on load output from 0 to 3000 Hz.Stability – The high-velocity, first-stage jet flow impinges onto a rigid receiver, solidly mounted in the second stage, and does not impinge on the mechanical feedback element. The rigid connection of the mechanical feedback element to the second-stage spool eliminates a wear point and reduces high gain at null.Null bias stability – Through symmetrical torque motor design and all welded/brazed construction, null shift resulting from vibration, temperature, and other environmental factors is minimized.Low maintenance – No filter replacements are required. First-stage oil passes through a single 90-micron screen that is easily removable for inspection without disassembling the valve.Servo-controlled second stage – The second-stage spool is precisely controlled by a high-gain, position-feedback servo-loop. Pressure balance and high force gain of the hydraulic first stage prevents displacement of the second-stage piston caused by any unexpected disturbance.Wide dynamic range – Characteristics of phase and amplitude versus frequency are virtually the same for inputs ranging from a few percent points to 50 percent of full flow. Dry torque motor – The hermetically sealed torque motor is completely isolated from the hydraulic fluid.Reduced life cycle cost – The Jet-Pipe servovalve’s rugged construction and unique design result in an overall lower life-cycle cost as well as unsurpassed reliability when compared to other designs.Certified for use in hazardous locations Non-incendive protection: class1, division 2, groups A, B, C, D - T135Certification: NI / 1 / 2 / ABCD / T3C Ta=135°CFeatures of the model 415 servovalvePasses 200-micron particles – Unique jet construction enables model 415 to receive and pass particles as large as 200 microns through both stages without malfunction.No unbalance from oil contamination – Because there is only one source of oil in the first stage, the valve will not become unbalanced or produce false hard over signals due to oil contamination of that stage.Low hysteresis – Hysteresis is normally less than three percent of rated current for all input signals (four percent maximum).Low threshold – Normally less than 0.1 percent of rated current (0.25 percent maximum).No filters – First-stage oil passes through a single 90-micron screen easily removable for inspection without disassembling the valve.Low temperature drift – Maximum null shift resulting from oil or environmental temperature changes is held to approximately two percent for each 100°F through symmetrical torque motor design.Servo-controlled second stage – Second-stage piston is precisely controlled by a high-gain, null-balance, and force-feedback servo. Pressure balance of the hydraulic preamplifier prevents displacement of the second-stage piston due to variations in supply or return oil pressure.Wide dynamic range – Characteristics of phase and amplitude versus frequency are virtually the same for inputs from a few percent to 50 percent of full flow.Dry torque motor – The hermetically sealed torque motor is completely isolated from the hydraulic fluid.Low gravity sensitivity – Acceleration and vibration tests on the valve show almost no effect on load.Features of the model 420 servovalvePasses 200-micron particles – Unique jet construction enables model 420 to receive and pass particles as large as 200 microns through both stages without malfunction.No unbalance from oil contamination – Because there is only one source of oil in the first stage, the valve will not become unbalanced or produce false hard over signals due to oil contamination of that stage.Low hysteresis – Hysteresis is normally less than three percent of rated current for all input signals (four percent maximum).Low threshold – Normally less than 0.1 percent of rated current (0.25 percent maximum).No filters – First-stage oil passes through a single 90-micron screen easily removable for inspection without disassembling the valve.Low temperature drift – Maximum null shift resulting from oil or environmental temperature changes is held to approximately two percent for each 100°F through symmetrical torque motor design.Servo-controlled second stage – Second-stage piston is precisely controlled by a high-gain, null-balance, and force-feedback servo. Pressure balance of the hydraulic preamplifier prevents displacement of the second-stage piston due to variations in supply or return oil pressure.Wide dynamic range – Characteristics of phase and amplitude versus frequency are virtually the same for inputs from a few percent to 50 percent of full flow.Dry torque motor – The hermetically sealed torque motor is completely isolated from the hydraulic fluid.Low gravity sensitivity – First stage is balanced among all three axes against the effects of lateral acceleration and vibration. Acceleration and vibration tests show almost no effect on load output from 0 to 2000 Hz.Features of the model 425 servovalvePasses 200-micron particles – Unique jet construction enables model 425 to receive and pass particles as large as 200 microns through both stages without malfunction.No unbalance from oil contamination – Because there is only one source of oil in the first stage, the valve will not become unbalanced or produce false “hard over” signals due to oil contamination of that stage.Low hysteresis – Hysteresis is normally less than three percent of rated current for all input signals (four percent maximum).Low threshold – Normally less than 0.1 percent of rated current (0.25 percent maximum).No filters – First-stage oil passes through a single 90-micron screen easily removable for inspection without disassembling the valve.Low temperature drift – Maximum null shift resulting from oil or environmental temperature changes is held to approximately two percent for each 100°F through symmetrical torque motor design.Servo-controlled second stage – Second-stage piston is precisely controlled by a high-gain, null-balance, and force-feedback servo. Pressure balance of the hydraulic preamplifier prevents displacement of the second-stage piston due to variations in supply or return oil pressure.Wide dynamic range – Characteristics of phase and amplitude versus frequency are virtually the same for inputs from a few percent to 50 percent of full flow.Dry torque motor – The hermetically sealed torque motor is completely isolated from the hydraulic fluid.Low gravity sensitivity – First stage is balanced among all three axes against the effects of lateral acceleration and vibration. Acceleration and vibration tests show almost no effect on load output from 0 to 2000 Hz.Features of the model 450 servovalvePasses 500-micron particles – Unique jet construction enables model 450 to receive and pass particles as large as 500 microns through both stages without malfunction.No unbalance from oil contamination – Because there is only one source of oil in the first stage, the valve will not become unbalanced or produce false hard over signals due to oil contamination of that stage.Low hysteresis – Hysteresis is normally less than three percent of rated current for all input signals (five percent maximum).Low threshold – Normally less than 0.1 percent of rated current (0.25 percent maximum).No filters – First-stage oil passes through a single 2500-micron screen easily removable for inspection without disassembling the valve.Low temperature drift – Maximum null shift resulting from oil or environmental temperature changes is held to approximately two percent for each 100°F through symmetrical torque motor design.Servo-controlled second stage – Second-stage piston is precisely controlled by a high-gain, null-balance, and force-feedback servo. Pressure balance of the hydraulic preamplifier prevents displacement of the second-stage piston due to variations in supply or return oil pressure.Wide dynamic range – Characteristics of phase and amplitude versus frequency are virtually the same for inputs from a few percent to +/- 25 percent of full flow.Dry torque motor – The hermetically sealed torque motor is completely isolated from the hydraulic fluid.Applications – Model 450 has been proven in service with high-flow applications such as power generation turbine controls, antenna control systems, and mobile equipment.
