Pressure Controlled Spool Application - Danfoss PVG 32 Technical Information

Technical Information
PVG 32 Proportional Valve Group
Function
24 | © Danfoss | November 2017
Fig. 4 Flow controlled spool
Fig. 5 Pressure controlled spool
The opening area of the variable orifice is at maximum at initial actuation and 0 at full stroke of the spool
and then the pressure created between the two orifices is led into the LS system in the usual way.
In this way the pump pressure is built up depending on the spool travel, e.g. the spool will then have to
be stroked to a position that the pump pressure is higher than the actual load pressure to make the oil
flow from P➝A/B.
When the load changes for a fixed spool position the flow to for the function will also change.
The valve section is now a load-dependent valve, but ensuring a constant pump pressure which is
important in obtaining a stable function.
Pump pressure vs. spool travel curve

Pressure controlled spool application

Pressure controlled spools should in principle only be used when you have stability issues. Typical
applications on a crane:
A
B
P005 625
A
B
P005 626
BC00000038en-US0803