Filter
Top Products
16
Parker Hannifin Corporation
Open-Center Directional Control Valve
VO40
Catalog HY17-8505/UK
The VO40 valve can be supplied in combinations from one to ten work sections. For each work section there is
a variety of spool options, actuators, positioners and port accessories. Work sections can have parallel, series,
and/or tandem circuitry. All types can be combined in the same valve assembly.
All work sections with hold in neutral spools have transition checks (load checks). All work sections with free flow
in neutral spools (motor) do not include transition checks (load checks). Contact Parker if you require a deviation
from this configuration.
Work sections are available with or without work port option machining. Integrated pilot-operated checks (Lock-
Out) are available in a specially machined casting (ordering code on page 20 [76 A/B]). A spacer section which
provides for more spacing between sections is also available (ordering code on page 20 [90]).
Examples of work port machining options:
Section without RV Cavities Section with RV Cavities
Section with PO Checks
The coding to specify a work section is made by 11 fields, as shown below:
[47] – Work Section Circuitry
P Parallel Circuitry.
T Tandem Circuitry – Provides priority to upstream sections.
S Series Circuitry– (In development).
The VO40 Pilot-Operated Check (Lock-Out) sections
provide near zero leakage and can prevent cylinder
drift when the spool is in the neutral position. When
the spool is shifted to a power position, oil is directed
to one work port. Return oil is momentarily blocked
until pilot pressure unseats the check (3.1:1 ratio). With
207 bar (3000 PSI) load, it will require 67 bar (968 PSI)
into the opposite work port to unlock.
The spool is a 4-way, 3-position free flow spool which
prevents system pressure leakage from building up
and unlocking the PO checks.
Ordering Information – Work Sections