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DESCRIPTION OF HOW THE VALVE OPERATES
Servomotor
The hydraulic control system consists of a cylinder filled with oil and an oscillating pump with thrust piston. There is also a
solenoid valve located between the intake chamber and the pump thrust chamber which serves to close the valve. The
piston moves against a sealed joint inserted into the cylinder; in turn, this joint hydraulically separates the intake chamber
from the delivery chamber. The piston transmits the stroke directly to the valve.
A disk is secured to the valve shaft and can be seen through a slit in the valve, indicating the stroke. Through an oscillating
system this disk simultaneously activates the limit switch contacts for the partial and nominal output positions.
Two - stage operation
When the valve receives the signal to open, the pump cuts in and the magnetic valve closes. The pump transfers the oil
under the piston to above it, forcing the piston downward, which compresses the closure return spring with the rod and
plate. When the valve reaches the first stage, a disk connected to the shaft activates contact "V1" by means of an oscillating
system. As a result, the pump cuts out and the valve remains in the first-stage position.
The pump begins functioning again only when terminal 3 is powered either from the control panel or directly by the power
regulator. The full load stroke terminates when the contact is tripped and the pump cuts out.
If the power regulator cuts off power supply to terminal 3, the magnetic valve opens and the valve will remain open until the
piston reaches the 1
st
stage position. If regulation is shut down because the power supply has been cut off, terminals 1 and
3 are no longer powered - this causes the servocontrol to close the valve in less than 1 second.
SUGGESTIONS FOR SETTING
1) We therefore advise you to prepare the
burner for ignition by setting screw V1
(regulating the gas flow to the 1
that the distance between the control lever
and the microswitch push-button does not
exceed 1 mm (see the figure below). Set
the combustion air gate in a highly closed
position.
2) Second flame. Set V2 in the position where
the gas flow required for the 2
obtained. Obviously, the position at which
V2 is set (the distance between the
microswitch control lever and the
microswitch push-button) must be greater
than that set for V1.
INSTRUCTIONS FOR SETTING LANDIS & GYR
mod. SKP 10.123A27 TWO STAGE GAS VALVES
st
flame) so
nd
flame is
Remove cover "A" to access the gas regulation screws.
To set gas flow to the 1
(V1) with a screwdriver.
To set gas flow to the 2
(V2) with a screwdriver.
In both cases, tightening the screw increases gas flow,
unscrewing it decreases the flow.
Screw "D" in terminal "IV" regulates the position at which
the "clean" contact is activated. This can be used for an
outside signal.
A = Driver identification plate
B = Flow direction indicator
C = Valve body identification plate
Microswitch push-button for valve 1
Microswitch control lever for valve 1
Screw setting the opening for the valve 1
31
Rev. 06/11/90
st
flame, turn the screw in terminal I
nd
flame, turn the screw in terminal III
st
stage
st
stage
st
N° 8881
stage (V1)
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