3 Product Description
Hydraulics
© Moog GmbH User Manual "D633-A Series" (CA80942-001; Version 1.0, 12/08) 16
3.3 Hydraulics
3.3.1 Open-loop flow control (Q-control)
Operational mode:
Open-loop flow control
(Q-control)
The valves are operated as open-loop flow control valves.
In open-loop flow control an open-loop control of the spool position is carried
out. The predefined command signal corresponds to a particular spool position.
The flow that is set depends not only on the spool position but also on the pres-
sure difference
∆
p at the individual control lands.
Chapter "5.1 Dependency of Flow and Pressure Drop", page 29
Chapter "5.2 Flow signal characteristic curve", page 29
3.3.2 Valve configurations and hydraulic symbols
Valve configurations
Depending on the model, the following valve configurations are possible:
• 2-way operation
Chapter "3.3.2.2 2-way and 2x2-way operation", page 17
• 3-way operation
Chapter "3.3.2.1 4-way and 3-way operation", page 16
• 4-way operation
Chapter "3.3.2.1 4-way and 3-way operation", page 16
• 2x2-way operation
Chapter "3.3.2.2 2-way and 2x2-way operation", page 17
3.3.2.1 4-way and 3-way operation
4-way and 3-way
operation
With 4-way operation the valves can be used to control the flow in ports A
and B (used as throttle valves).
Port A or B must be blocked in order to obtain 3-way operation.
Leakage port Y must be used if the pressure in tank port T exceeds a value of
50 bar (725 psi).
Chapter "3.3.3 Leakage port Y", page 17
The valves are available with zero lap, less than ±3 % or ±10 % positive over-
lap.
Hydraulic symbols: 4-way
and 3-way operation
Chapter "3.2.1.1 Valves with fail-safe function F, D or M", page 14
WARNING
To ensure faultless valve operation, it is necessary to con-
figure the valve correctly with regard to flow and pressure.
Figure 3: 4-way operation with mechanical
fail-safe function F (hydraulic symbol)
Figure 4: 3-way operation with mechanical
fail-safe function F (hydraulic symbol)
