Product Manual

PRINCE MANUFACTURING CORPORATION • P.O. BOX 7000 • NORTH SIOUX CITY, SOUTH DAKOTA 57049-7000
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V37
VALVES
CATV 01-04-09-02
RD-5000 SERIES STANDARD AND SPECIAL FEATURE DESCRIPTIONS
TWO SPOOL
“JOYSTICk” HANDLE
This handle will operate both spools
using only one lever handle. The
two spools can be operated either
independently or simultaneously
depending on handle movement.
The above drawing shows a section view of a 2-spool valve, Model RD522GCGA5A4B1.
This is shown as a representative valve model. Other models will differ in appearance.
LOAD CHECk:
The load check feature is standard on all
RD-5000 series valves. Each spool has a
separate load check. The load check will
prevent the fall of a cylinder as the spool
is shifted. It also prevents the back-ow of
oil from the work port to the inlet. As shown
below the pump must build up enough
pressure to overcome the pressure on the
work port caused by the weight of the load
before the cylinder can move.
Please note that the load check has nothing
to do with how well the valve will hold up a
cylinder with the spool in neutral. The load
check is functional only when the spool is
shifted.
OPEN CENTER APPLICATIONS:
The Standard RD-5000 Series Valves are open center type valves.
For open center valves the hydraulic oil is directed from the inlet to the
outlet, or power beyond, through the open center passage when the
spools are in neutral. Moving one or more spools closes off the open
center passage and directs oil to the work ports.
Open center systems most often contain xed displacement pumps.
The PMC hydraulic PTO pumps are xed displacement gear pumps.
The maximum pressure in an open center system is controlled by a
relief valve. The RD-5000 series valves have a built in relief valve for
this purpose.
RD-5000 Series spool options A, C, E and G are all open center spools
when used with power beyond options A, B, C and F.
CLOSED CENTER APPLICATIONS:
RD-5000 Series Valves are available as closed center type valves. For
closed center valves the oil through the open center passage is blocked
when the spools are in neutral.
Closed center systems often use a variable displacement pressure
compensated pump. When this type of pump is used in a closed center
system the system pressure is controlled by the pressure compensator.
When the spools of RD-5000 series valve are in neutral, system
pressure is maintained at the inlet of the valve. For this reason a relief is
normally not required or must be set at a higher pressure than the pump
compensator. RD-5000 Series spool options C, E and G are converted
to closed center by installing a closed center conversion plug, power
beyond option D.
PLEASE NOTE that this closed center option does not provide for the
drain off of standby spool leakage. This can allow a very small amount
of oil to enter the work ports when in neutral.
The above drawing shows a section view thru work
ports of a RD-5100 Single Spool Valve.
LOAD
CYLINDER
OIL FROM PUMP
OUTLET
CONVERSION PLUG ALLOWS
ADDITION OF POWER BEYOND PORT
RETURN CORE. OIL FLOWS
AROUND SPOOL TO OUTLET
TANDEM CENTER SPOOL
FLOAT SPOOL
4 STANDARD SPOOLS
INLET
WORK PORT "A" CORE
DIFFERENTIAL POPPET
RELIEF
"POWER" CORES FROM LOAD CHECK
WORK PORT "B" CORE
FLOAT DETENT
SPRING CENTER
9 STANDARD SPOOL ATTACHMENTS
SPOOL SHIFTED
FULLY "OUT"
WORK PORT "A"
LOAD CHECK
POPPET
WORK PORT "B"
LOAD
CYLINDER
OIL FROM PUMP
OUTLET
CONVERSION PLUG ALLOWS
ADDITION OF POWER BEYOND PORT
RETURN CORE. OIL FLOWS
AROUND SPOOL TO OUTLET
TANDEM CENTER SPOOL
FLOAT SPOOL
4 STANDARD SPOOLS
INLET
WORK PORT "A" CORE
DIFFERENTIAL POPPET
RELIEF
"POWER" CORES FROM LOAD CHECK
WORK PORT "B" CORE
FLOAT DETENT
SPRING CENTER
9 STANDARD SPOOL ATTACHMENTS
SPOOL SHIFTED
FULLY "OUT"
WORK PORT "A"
LOAD CHECK
POPPET
WORK PORT "B"