Browse Standards ARP4493
Historical ISSUED 2000-07-01

Aerospace - Direct Drive Servovalves ARP4493

The recommendations contained in this ARP are primarily confined to the input and output characteristics of Direct Drive Servovalves (DDV). The only exception to this approach involves the definition and specification of chip shear force, which is not typically measurable by nondestructive external testing. The information presented should be useful in standardizing the terminology, the specification of physical and performance parameters, and the test procedures used in conjunction with these components.
Direct drive servovalves are of two basic types; open loop and closed loop. In the case of open loop direct drive servovalves, the significant input is the motor current as is the case with electrohydraulic servovalves covered in ARP490. Closed loop direct drive servovalves include a means of position feedback and rely on an electronic controller to control its performance characteristics. Because of the importance of the closed loop category of DDVs, many specifications will be written for the closed loop performance. To generalize this document, the system input signal has been referred to as the “command" and applies equally well to open loop valves, in which the command will usually be expressed in amps, and to closed loop valves which usually receive commands as an input voltage to the valve controller. Many provisions of this document apply equally to larger tandem Main Control Valve (MCV) type DDVs as well as standard size single hydraulic system valves.
The specifications contained herein should be used to describe direct drive flow control servovalves. Additional specifications may be necessary to define special requirements for specific control systems. Also, specialized test procedures may be necessary to measure DDV performance in these unusual specification areas. These considerations are beyond the scope of this recommended practice.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 10% off list price.
Login to see discount.
Special Offer: AeroPaks offers a customized subscription plan that is cost-effective and allows you to choose the number of downloads and Aerospace and Aerospace Material documents you need. Find more information here.
We also recommend:

Ground Support Equipment Hydraulic Systems, Design and Installation, Recommended Practices For


View Details


Assessing Cleanliness of Hydraulic Fluid Power Components and Systems


View Details


Aerospace Fluid Power - Waste Reduction Practices for Used Phosphate Ester Aviation Hydraulic Fluid


View Details

Get Involved

Want to participate in updating this standard?