Hydraulic Valves B Flashcards
valve mounted on top of a stack valve
DCV
valve mounted on sub plate on a stack valve
relief valve
valve mounted between top plate and sub plate on a stack valve
pilot operated check valve and flow control valve
symbol for pilot supply on a stack valve
X
symbol for pilot drain on a stack valve
Y
plate for unused section of stack valve
blanking plate
2 types of cartridge valve
slip in and screw in
cartridge valve for low flow circuits 30-35 GPM
screw in
cartridge valve for large flows over 30 GPM
slip in cartridge
what 2 specification determine whether a slip in cartridge opens
area ratio
pressure at each port
cartridge valve treated as throw away
screw in valve
cartridge valve can be repaired
slip in valve
diagonal lines on solenoid indicate
force can be variable
proportional or servo valve
more expensive, higher accuracy
servo valve
proportional or servo valve
more rugged and dirt tolerant
proportional valves
proportional spool movement is proportional to
electrical input
electronic control used to control the electrical input to a solenoid
amp card
notched spool are unique to this valve
proportional valve
notched spools can control flow rate through
metering notches
to minimize delay in flow, this control briefly boosts the power to make the spool jump quickly across the overlap distance
dead band compensation
signal to ensure the spool moves freely
dither
function to control acceleration and deceleration
ramp
cannot sense how accurately the actuator is responding to the control settings
open loop system (no feed back)
sense the spool position and feeds the signal back to the summing junction in the amplifier
LVDT
sends a signal to the controller to give it the position of the spool
closed inner loop system
connects a position sensor on the actuator to the summing junction in the amplifier control
closed out loop system
3 types of pressure controls on proportional valve
nozzle
plate
poppett
pressure control on proportional valve for less than 1 gpm(pilot)
nozzle
pressure control on proportional valve highly responsive and accurate
plate
main components of a servo valve
torque motor and spool valve
3 types of servo valve
flapper, nozzle, jet pipe
term used to express how accurately the spool moves compared to the input current
hysteresis
filter microns needed for servo valve
2-3 microns
should a servo valve be repaired
no
