■CAUTIONS ON USE●VALVESCSOLENOID VALVES / DIRECTIONAL CONTROL VALVES① Install a solenoid valve so that the spool is positioned horizontally.
② The maximum flow of a solenoid valve varies depending on the model, the hydraulic circuit configuration,
the operating conditions, and other factors.
③ Since a valve can malfunction if air enters it during installation, be sure to bleed the air before operating thevalve.
④ A valve may fail to operate if the solenoid is kept energized or de-energized for a long time with pressure
applied. If a valve is to be used for such an application, please consult us.
⑤ The no spring detent type (2WD-BcA) is used in applications where the spool position has to be held in thede-energized state.
Where there is excessive vibration in T port back pressure, momentary flow, vibration and/or contamination,
keep the valve energized to secure the spool position.
⑥ When operating the solenoid valve manually, push in the axial direction horizontally. Do not push with asharp tool. If the internal diameter section where the manual pin slides is damaged, it will cause operation
failure or external leakage.
⑦ Be sure to use mounting bolt of the strength of Class 12.9 or higher.
⑧ Tighten the valve mounting bolts to a tightening torque 6 to 8 N-m. Poor tightening will cause external
leakage and excessive tightening will cause operation failure.

●ELECTRICITY① When an AC double solenoid type is used, take care not to energize SOLa and SOLb simultaneously. The
solenoid may burn.
② When a DC solenoid is used with a contact relay, generation of spark is restricted by the surge absorbing
device incorporated in the terminal box. However, the relay deposition varies depending on the operating
conditions (relay type and switching frequency).
③ The varistor voltage is 110 V for the DC type and 470 V for the AC type. If an SSR is used, check that theload voltage range of the SSR is not exceeded. Where a PLC is connected directly, select a type with thePLC output card or M12-4 pin connector type to protect the PLC output card.
④ When a diode is used to prevent generation of back electric force, it is advisable to use RH2F (SankenElectric).
⑤ Use of the diode above is also recommended to prevent an indicator lamp from lighting erroneously when
the power circuit is shut off by an emergency stop button, using a transistor output card.
⑥ Shut off the power supply before connecting cables.
⑦ A double-solenoid type valve is provided with a COM short-circuit jumper in the terminal base to facilitate
wiring work. Connecting a cable to either of the power source common terminals allows the valve to be put
into operation. When SOLa and SOLb do not use the COM, use after removing the COM short-circuitjumper from the terminal block.
⑧ The tightening torque specification of the terminal screws (M3) is 0.8 Nm ±10%.
⑨ The tightening torque specification of the self-tapping screws on the lid is 1 Nm ±10%.
⑩ Since a lamp is wired in parallel with a solenoid, it turns on regardless of the solenoid status when the poweris supplied to the terminal block.
⑪ Do not apply a voltage other than that specified to the terminal block.
⑫ Since the coil surface becomes hot if a valve is used continuously, do not touch the coil directly by hand.
⑬ Use the cable type and size appropriate for the valve.
⑭ When connecting M12-4 pin type connector, tighten to 0.39 to 0.49 N·m.

●FLUID① Use petroleum-base fluid (equivalent to ISO VG22, VG32, or VG46) in a temperature range from 0ºC to 65ºC.
Using fluid outside the specified temperature range will cause operation failure. When replacing the fluid,
always use fluid of the same brand.
② Maintain fluid cleanliness at a level better than oil contamination level ISO 11218 class 12 (NAS1638 Class12). Use of contaminated fluid will shorten valve life and cause valve failure.
③ Take due care to ensure that no fluid of any other kind, coolant etc. enters the fluid being used.
④ Generally, standard specification solenoid valves can be used for water-glycol or fatty acid ester. However, it
is advisable to check if the O-ring is compatible with the fluid to be used.

C−2

■SPOOL TYPES AND REPRESENTATION
Spool type is classified as shown in the table below depending on the how the fluid flows in the valve when the spool is in the neutralposition.
Spool Type
Category Representation

Spool Position andValve Passages(Spool in Neutral Position)

Symbol
A B

BCA
P R

A P B R

All ports are closed and there is no oil flow when the spool is in theneutral position.
Due attention must be paid to leaks and surge pressure generated
during switching.
Due attention must be paid when the valve is used to hold thecylinder at the fixed position for a long time.
This type of spool is used in applications where the pump is
unloaded and the cylinder is floated when the spool is in the neutralposition.
Due attention must be paid since the cylinder may operate dependingon the back pressure at the R port.

A B

BDA
P R

A P B R

BD1A
P R

A P B RA B

BGAP RA P B R

This type of spool is used to hold the P port pressure and float thecylinder when the spool is in the neutral position.
This type is appropriate in a cylinder holding circuit where a checkvalve is used.
Due attention must be paid to the surge pressure at the P port.
Due attention must be paid to cylinder pop-out.
This type of spool is similar to the BGA type spool, butthe flow from the A and B ports to the R-port is throttled.
This type is used for preventing cylinder pop-out.

A B

BG1A
P R

A P B RA BBMAP R

A P B R

This type of spool is used to close the P and A ports and open the B
port when the spool is in the neutral position.
Due attention must be paid when the valve is used to hold thecylinder at the fixed position for a long time.
Due attention must be paid to the surge pressure at the P port.
Due attention must be paid to cylinder pop-out.
This type of spool is similar to the BMA type spool, but the flow fromthe B port to the R port is throttled.
This type is used for preventing popping out of a cylinder.

A B

BM1AP RA P B RA BAEBP R

A P B R

This type of spool is used to unload a pump and close the A and B
ports when the spool is in the neutral position. Although valves canbe connected in series and used alternately, due attention must bepaid to the pressure loss and the back pressure at the R port.
Due attention must be paid when the valve is used to hold thecylinder at the fixed position for a long time.
Due attention must be paid to the fact that the fluid passage
symbols at the switching position are the reverse of those on othertypes.
This type of spool is used to unload a pump and close
only the B port when the spool is in the neutral position.

A B

BHA
P R

A P B R
A B

BcA

No-spring TypeP R

A P B R

All ports are connected with each other to allow fluid flow throughthem during the switching period. Due attention must be paid to thepressure drop at the P, A and B ports that occurs during switching.
The solenoid must always be energized.
Due attention must be paid to the valve installation direction.

A B

BdA
P R

A P B R

A B

BgA
P R

With this type of spool, all ports are closed and there is no fluid flow
during the switching period.
Due attention must be paid to the surge pressure generated duringswitching.
The solenoid must always be energized.
Due attention must be paid to the valve installation direction.
NOTE: A valve with a detent mechanism is available.

A P B R

Only the P port is closed during the switching period. Due attention
must be paid to the surge pressure generated at the P port.
Due attention must be paid to the pressure drop at the P, A and B
ports that occurs during switching.
The solenoid must always be energized.
Due attention must be paid to the valve installation direction.

C−3CSOLENOID VALVES / DIRECTIONAL CONTROL VALVESThis type of spool is similar to the BDA type spool, but all ports aresemi-opened when the spool is in the neutral position. Less shock isgenerated compared to the BCA type.
Due attention must be paid since the cylinder may operate
depending on the back pressure at the R-port.

A B

Spring Center Type

Function and Use

Spool Type
Category Representation

Spool Position andValve Passages(Spool in Neutral Position)

SymbolWith this type of spool, all ports are closed and there is no fluid flow
during the switching period.
Due attention must be paid to the surge pressure generated duringswitching.

A B

BcA
P R

A P B R
All ports are connected with each other during the switching period.
Due attention must be paid to the pressure drop at the P, A and B
ports that occurs during switching.

A B

BdA
P R

CA P B R

SOLENOID VALVES / DIRECTIONAL CONTROL VALVES

Only the P port is closed during the switching period.
Due attention must be paid to the surge pressure generated at the P
port.
Due attention must be paid to the pressure drop at the A and B portsthat occurs during switching.

A B

BgA
P R

A P B R
With this type of spool, all ports are closed and there is no fluid flow
during the switching period.
Due attention must be paid to the surge pressure generated duringswitching.
The R port must not be plugged and must be piped to the reservoir.

A B

Spring-offset Type

Function and UseKcPP R

A P B R
When the spool is offset by spring, all ports are closed and there isno fluid flow during the switching period.
Due attention must be paid to leaks and surge pressure generated
during switching.

A BBC
P R

A P B R
This type of spool is used to float a cylinder when the spool is offsetby spring.
Due attention must be paid to the surge pressure generated at the Pport.

A B

BGP R

A P B R
With this type of spool, all ports are closed and there is no oil flow
when SOLa is energized, but due attention must be paid to leaks andsurge pressure generated during switching.

A BCAP R

A P B R(Reference) Valve Passage Types
The valve passage is configured by the combination of passages opened at each spool position. The passage opened at each spool
position is classified as shown in the table below according to the port connection state in the valve, and the valve passage isexpressed by arranging the letters that represent the opened passage at the relevant spool position.
Character

A
A B

B
A B

CA B

DA B

E
A B

F
A B

GA B

H
A BK
A B

P R

P R

P R

P R

P R

P R

P R

P R

P R

M

NP

Q

RS

D1

G1

M1

A B

A B

A B

A B

A B

A B

A B

A B

A B

P R

P R

P R

P R

P R

P R

P R

P R

P R

Passage
SymbolCharacter
Passage
SymbolNOTE 1: P represents a pressure port, A and B represent connection ports to a cylinder or other actuator, and R represents a connection port to a reservoir.
NOTE 2: To express the transient state, a lower case letter is used.
NOTE 3: The numeral 1 in the characters indicates throttling of the A and/or B port passage.
(The size of the numeral is the same as an upper case letter.)C−4