MTS Series 315 Load Frame - Manual (Page 9)

Series 315 Load Frame Introduction 9
Servovalves Servovalves regulate the direction and flow of the hydraulic fluid to and from a
hydraulic actuator. The servovalve responds to the polarity and magnitude of the
command signal generated by the controller.
Hydraulic distribution Hydraulic distribution includes a hydraulic manifold (also called an actuator
manifold or hydraulic service manifold) which controls the hydraulic pressure to the
load frame. The manifold includes solenoid valves that control the hydraulic
pressure (off, low, or high). An actuator manifold is mounted directly to the actuator
on the load frame. A hydraulic service manifold (HSM) is located near the load
frame and connects to the actuator with hydraulic hoses.
Most hydraulic distribution systems will also include a check valve in the return line.
The purpose of this check valve is to minimize actuator drift where pressure is
present on the return line without servo control of the 315 frame.