Pressure Unloading Valve0 pages
Pressure Unloading Valve, Size 4
Qmax = 30 l/min, pmax = 250 bar
Two-stage, various on-off pressure differentials, with manual adjustment
Series DWPB-4N…
S Compact construction for
cavity type AN – 3/4-16 UNF
S External pilot drain
S On-off differential independent of tank line pressure
S Choice of 5 on-off differentials
S 3 pressure ranges available
S With integral pressure-relief function
S Available with hand-knob
S All exposed parts with zinc-nickel plating
S Can be fitted in a line-mounting body
1
Description
Series DWPB-4N… cartridges are size 4, two stage, high
performance pressure-unloading valves with an 3/4-16
UNF mounting thread. They consist of a spool-type main
stage and a leak-free, ball-type pilot stage. Unloading val
ves are used wherever a pump has to be disconnected from
and re-connected to a pressure circuit. For this purpose, ei
ther the 'Off' pressure or the 'On' pressure of the cartridge
can be set. When the 'Off' pressure is set, the 'On' point will
depend on the selected percentage on-off differential, or the
other way round. To disconnect the pump, the cartridge re
sponds to rising pressures at ports 4 and 1 by opening the
connection from 4 3. This connection is then kept open
until the selected percentage on-off differential is reached
(falling pressure at port 1) and the connection 4 3 closes
2
again (the 'On' point). Because ports 2 and 3 are run back
to tank separately, the on-off differential (bar) is unaffected
by any back-pressure in port 3. These unloading valves are
predominantly used in accumulator-charging circuits,
2-pump systems, and circuits for fast-ad vance feed
changeover, and in such cases the cartridges also provide
a pressure-relief function e.g. for protecting the pump (see
the application examples). All external parts of the cartridge
are zinc-nickel plated to DIN 50 979 and are thus suitable
for use in the harshest operating environments. If you intend
to manufacture your own cavities or are designing a linemounting installation, please refer to the section “Related
data sheets”.
Symbol
3
2
1
4
3
Technical data
General characteristics
Description, value, unit
Designation
pressure unloading cartridge valve
Design
two-stage, with manual adjustment,
various on-off pressure differentials
Mounting method
screw-in cartridge 3/4-16 UNF
Tightening torque
40 Nm ± 10 %
Size
nominal size 4, cavity type AN
Reference: 400-P-379101-EN-01
Issue: 08.2014
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