MTS Hydraulic Service Manifold Model 293-12B - Manual (Page 42)

HSM Control
Solenoid control valves located on the HSM control manifold are controlled by the system controller; they
cannot be controlled locally. Low-pressure, high pressure, or pressure-off conditions are operated from
the system controller (which can be controller software, a control panel, or a remote module).
The manifold design requires the HSM to be switched to low pressure from the off condition. This makes
the sequence to obtain a high-hydraulic pressure output, from off to low to high. Pressure is then reduced
by returning to low pressure mode.
Smooth pressure transitions between one mode and another are automatically provided by the HSM.
Pushing the Emergency Stop or Hydraulics Off pressure control switch causes the HSM to turn off input
hydraulic pressure and connect the pressure output to the return line.
HSM Pilot Pressure Considerations
The HSM is equipped with a hydraulic circuit which provides separate filtered fluid at HPU pressure to
operate the pilot stage of multistage servovalves.
Warning :
Pilot pressure is always present, as long as pressure is available from the HPU. Turning HSM
pressure on and off, or changing between low and high output pressure, does not affect the
pilot pressure output.
Disturbing the pilot pressure circuit can cause unexpected actuator movement which can
cause personal injury, damage to equipment, or both.
Ensure that the HPU is turned off before working with the pilot pressure circuit.
42 | Series 293 Hydraulic Service Manifold Product Information
Operation