5
The total pressure drop across the valves two series orifices
“A” and “B” must equal 1000 PSI, (the difference between
inlet and outlet pressures). The normal drop across orifice
“A” is between 60 and 80 PSI. (Use 75 PSI for this
explanation.) Orifice “B” will drop 925 PSI, the total of the
two pressure drops is the difference between inlet and outlet
pressures.
If the work load increases, the outlet pressure increases. To
keep a constant flow, the pressure drop across orifice “A”
must not change. This is accomplished as follows:
The increased outlet pressure is sensed against the spring
end of the hydrostat, causing it to move down, increasing the
area of orifice “B” and reducing the pressure drop across it.
This increases the pressure available at the up–stream side
of orifice “A”. 200 in
3
/minute will continue to flow as long as a
75 PSI pressure drop is maintained across orifice “A”.
If the work load were to decrease, (output PSI lower), a
similar set of events will begin, except in the opposite
direction. The hydrostat will move up. Orifice “B” reduces in
size, increasing the pressure drop across it, lowering the
pressure at the up–stream side of orifice “A” and a constant
200 in
3
/minute will continue to flow through the valve.
Torque Motor
– A high force permanent magnet torque
motor imparts linear motion to the torque motor armature.
The deflection of the armature is directly proportional to
current through he torque motor coils. This armature is
linked to the metering spool with a wire and set screw. When
current is applied to the torque motor coils, the armature is
deflected to a certain position and the metering spool
follows, opening or closing orifice “A”. When orifice “A”
changes, the flow control will vary flow through the valve and
hold it constant at the new setting of the metering spool
regardless of workload.
Section IV – Installation and Operating Instructions
A. Installation Drawings
The installation drawing listed in Table 1 will show installation
dimensions and port locations.
B. Mounting
The FCGT- 02-*-11 Flow Control Valve is designed for man-
ifold or subplate mounting. Refer to the installation drawing
for subplate dimensions.
C. Piping And Tubing
1. All pipes and tubing must be thoroughly cleaned
before installation. Recommended methods of cleaning are
sand blasting, wire brushing and pickling.
NOTE
For instructions on pickling, refer to instruction
sheet 1221 – S.
2. To minimize flow resistance and the possibility of
leakage, only as many fittings and connections as are
necessary for proper installation should be used.
3. The number of bends in tubing should be kept to a
minimum to prevent excessive turbulence and friction of oil
flow. Tubing must not be bent too sharply. The
recommended radius for bends is three times the outside
diameter of the tube.
D. Hydraulic Fluid Recommendations
Oil in a hydraulic system performs the dual function of
lubrication and transmission of power. It constitutes a vital
factor in a hydraulic system, and careful selection should be
made with the assistance of a reputable supplier. Proper
selection of oil assures satisfactory life and operation of system
components with particular emphasis on hydraulic valves.
Data sheet I-286-S for oil selection is available from Vickers
Technical Publications, Troy, MI 48007-0302.
Oil recommendations noted in the data sheet are based on our
experience in industry as a hydraulic component manufacturer.
Where special considerations indicate a need to depart from
the recommended oils or operating conditions, see your
Vickers representative.
Cleanliness
Thorough precautions should always be observed to insure
the hydraulic system is clean.
1. Clean (flush) entire new system to remove paint, met-
al chips, welding shot, etc.
2. Filter each change of oil to prevent introduction of
contaminants into the system.
3. Provide continuous oil filtration to remove sludge, and
products of wear and corrosion generated during the life of
the system.
4. Provide continuous protection of system from entry of
airborne contamination, by sealing the system and/or by
proper filtration of the air.
5. During usage, proper oil filling and servicing of filters,
breathers, reservoirs, etc., cannot be over emphasized.
6. Thorough precautions should be taken, by proper
system and reservoir design, to insure that aeration of the oil
will be kept to a minimum.
E. Overload Protection
A relief valve is required to limit pressure in the system and to
protect components from excessive pressure. The relief valve
should be connected in the circuit at the outlet of the pump,
before the FCGT flow control valve. The relief valve pressure
setting should be adjusted just above the minimum work
requirements of the system. DO NOT exceed the pressure
rating of any system component or a malfunction may result.
