PVG 32 Proportional Valves Technical Information

PVG 32 Proportional Valve
Technical Information
System safety
1.
MAXIMUM SAFETY
DEMANDS
When the fault monitoring system in PVEH is connected, the reaction to electrical and
mechanical faults (e.g. a spool seizure) is fast and operator-independent. See page 17
“fault monitoring”.
A system can be protected against many electrical, hydraulic and mechanical faults by
building in components as shown in the diagram:
R: Alarm logic EHA (or relay) connected to the fault monitoring system in PVEH
E: Electrical emergency stop
M: Solenoid valve
C: Pilot-operated check valve
The alarm logic EHA cuts off current to the solenoid valve (M) when PVEH monitoring
registers a fault. The solenoid valve then leads the oil flow direct from pump to tank.
Thus all functions are without operating pressure, i.e. locked in position, because there is
no pilot pressure on the pilot operated check valve (C).
Actuation of the emergency switch (E) cuts off current to the proportional valve and the
solenoid valve (M). Actuation in this case is manual, but the result is the same as above.
Stopping or disconnecting the pump drive motor is another safety measure, if the system
reaction time can be accepted.
Note:
The neutral position switch in the remote control units should not be used.
PVEH with fault monitoring must have a constant voltage supply.
50 520L0344