DB20G3-4X/350/12 W65

Manufacturer: Bosch Rexroth

Material #: R978871023

Model : DB20G3-4X/350/12 W65

***Disclaimer: The following summary contains information gathered from various sources such as product descriptions, technical specifications and catalogs. While efforts have been made to provide accurate details, inaccuracies may occur. It is advised to verify all information by contacting Bosch Rexroth directly.***
The Bosch Rexroth DB20G3-4X/350/12 W65 (R978871023) is a pilot-operated pressure relief valve designed to regulate the operating pressure within hydraulic systems. This valve features a robust housing and a pilot control valve with various adjustment types for precise pressure customization. The main spool in the valve is acted upon by the pressure in channel P, and when this pressure exceeds the set value, poppet opens against its spring, allowing hydraulic fluid to flow into the spring chamber before being directed either internally or externally to the tank. Equipped with a pressure gauge connection for monitoring operating pressure, the DB20G3-4X/350/12 W65 ensures consistent performance and reliability. The valve also includes an unloading feature and can switch to an alternative second pressure rating via port X, enhancing its versatility in different hydraulic applications. This model is intended for subplate mounting and adheres to ISO NG6 and ISO NG10 porting patterns for secure installation. Users have several options for adjusting the pressure settings, including a rotary knob, a sleeve with hexagon and protective cap, a lockable rotary knob with scale, or a simple rotary knob with scale. With its varying pressure ratings, this Bosch Rexroth valve can operate at a maximum of 350 bar and accommodate maximum flow rates as specified by its size component series. The DB20G3-4X/350/12 W65 is engineered for optimal control in sophisticated hydraulic systems where precise pressure limitation is crucial.

$782.00 USD

More are expected on June 9, 2025

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Status: This product is temporarily out of stock.

Qty: Delivered as early as June 9, 2025 when ordered in

This product is eligible for factory repair.

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For subplate mounting
Porting pattern according to ISO 6264-06-09-*-97 (NG10) and ISO 6264-08-13-*-97 (NG25) For threaded connection 4 adjustment types for pressure adjustment, optionally
• Rotary knob
• Sleeve with hexagon and protective cap
• Lockable rotary knob with scale
• Rotary knob with scale 5 pressure ratings

Valves of type DB are pilot-operated pressure relief valves. They are used for limitation of the operating pressure.

The valves basically consist of housing (1) and pilot control valve (2) with adjustment type.

The pressure applied to channel P acts on the main spool (3). Via the nozzle bores (4 and 5), the pressure is at the same time applied to poppet (6). If the pressure in channel P exceeds the value set at spring (7), poppet (6) opens against spring (7). Via the nozzle bores (4 and 5), the hydraulic fluid from channel P now flows into the spring chamber (8). From here, it is led into the tank internally (version "–"), via the control line (9 and 10), or externally (version "Y") via the control line (9 and 11).

Due to the state of equilibrium at the main spool (3), hydraulic fluid flows from channel P to channel T, maintaining the set operating pressure.

A pressure gauge connection (12) allows for the control of the operating pressure.

The pressure relief valve can be unloaded or switched to another pressure (second pressure rating) via port X (13).

01	02	03	04	05		06		07	08	09	10	11	12
DB					–	4X	/					W65	*

Type
01	Pressure relief valve	DB
02	Without directional valve	no code
Size
03	Size 10
	Subplate mounting "–"	10
	Threaded connection "G" (G1 1/2)	10
	Size 25
	Subplate mounting "–"	20
	Threaded connection "G" (G3/4)	15
	Threaded connection "G" (G1)	20
Type of connection
04	Subplate mounting	–
04	Threaded connection	G
Adjustment type
05	Rotary knob	1
	Sleeve with hexagon and protective cap	2
	Lockable rotary knob with scale	3 1)
	Rotary knob with scale	7
Component series
06	Component series 40 ... 49 (40 ... 49: unchanged installation and connection dimensions)	4X
Pressure rating
07	Set pressure up to 50 bar	50
	Set pressure up to 100 bar	100
	Set pressure up to 200 bar	200
	Set pressure up to 315 bar	315
	Set pressure up to 350 bar	350
Pilot oil supply and pilot oil return (see also Symbols)
08	External pilot oil supply, internal pilot oil return	X
	Internal pilot oil supply, external pilot oil return	Y
	Pilot oil supply and pilot oil return external	XY
Version
09	Standard version	no code
09	Valve for minimum cracking pressure (not suitable for mutual relief!)	U
Seal material
10	NBR seals	no code
	FKM seals	V
	(other seals upon request) Attention! Observe compatibility of seals with hydraulic fluid used!
Installation position
11	Vertical installation position of the screw-in cartridge valve (cartridge)	W65
12	Further details in the plain text	*

	1) H-key with material no. R900008158 is included in the scope of delivery.

Notice:

Preferred types and standard units are contained in the EPS (standard price list).

general

Size			10	25
Weight	Subplate mounting "–"	kg	1.6	2.3
	Threaded connection "G"	kg	2.95
Installation position			any
Ambient temperature range	NBR seals	°C	-30 … +80
	FKM seals	°C	-15 … +80
Minimum stability of the housing materials			Housing materials are to be selected so that there is sufficient safety for all imaginable operating conditions (e.g. with regard to pressure resistance, thread stripping strengths and tightening torques).

hydraulic

Size			10	25
Maximum operating pressure	Port P	bar	350
	Port X	bar	350
	Port T	bar	315
Maximum counter pressure	Port Y	bar	250
Minimum set pressure			flow-dependent, see characteristic curves
Maximum set pressure		bar	50 100 200 315 350
Maximum flow	Subplate mounting "–"	l/min	200	400
				G3/4	G1
	Threaded connection "G"	l/min	150	200	300
Hydraulic fluid			see table below
Hydraulic fluid temperature range	NBR seals	°C	-20 … +80
	FKM seals	°C	-15 … +80
Viscosity range		mm²/s	10 … 800
Maximum admissible degree of contamination of the hydraulic fluid 1)			Class 20/18/15 according to ISO 4406 (c)

1)	The cleanliness classes specified for the components must be adhered to in hydraulic systems. Effective filtration prevents faults and simultaneously increases the life cycle of the components. For the selection of the filters, see www.boschrexroth.com/filter.

Hydraulic fluid		Classification	Suitable sealing materials	Standards	Data sheet
Mineral oils		HL, HLP	NBR, FKM	DIN 51524	90220
Bio-degradable	Insoluble in water	HETG	FKM	ISO 15380	90221
	Insoluble in water	HEES	FKM	ISO 15380	90221
	Soluble in water	HEPG	FKM	ISO 15380	90221
Important information on hydraulic fluids: For further information and data on the use of other hydraulic fluids, please refer to the data sheets above or contact us. There may be limitations regarding the technical valve data (temperature, pressure range, life cycle, maintenance intervals, etc.). The ignition temperature of the hydraulic fluid used must be 50 K higher than the maximum surface temperature. Bio-degradable: If this hydraulic fluid is used, small amounts of dissolved zinc may get into the hydraulic system.

For applications outside these parameters, please consult us!

(measured with HLP46, ϑOil = 40 ±5 °C)

Inlet pressure dependent on the flow

Subplate mounting

Minimum set pressure and circulation pressure dependent on the flow 1)
Standard version

1)	The characteristic curves apply to the pressure at the valve output pT = 0 bar across the entire flow range.

Minimum set pressure and circulation pressure dependent on the flow 1)
Version “U”

1)	The characteristic curves apply to the pressure at the valve output pT = 0 bar across the entire flow range.

Threaded connection

Minimum set pressure and circulation pressure dependent on the flow 1)
Standard version

1)	The characteristic curves apply to the pressure at the valve output pT = 0 bar across the entire flow range.

Minimum set pressure and circulation pressure dependent on the flow 1)
Version “U”

1)	The characteristic curves apply to the pressure at the valve output pT = 0 bar across the entire flow range.

Notices:

The characteristic curves were measured with external, depressurized pilot oil return.

Due to the internal pilot oil return, the inlet pressure increases by the output pressure present in port T.

Type DB…–…

Type DB…X…

Type DB…Y…

Type DB…XY…

Subplate mounting

Size 10

Dimensions in mm


Required surface quality of the valve contact surface

1	Name plate
2	Port X for remote control, optional
3	Y port for pilot oil return, external
4	Adjustment type "1"
5	Adjustment type "2"
6	Adjustment type "3"
7	Adjustment type "7"
8	Lock nut SW22, tightening torque MA = 10±5 Nm
9	Hexagon SW10
10	Hexagon SW30, tightening torque MA = 50 Nm
11	Space required to remove the key
12	Locating pin
13	Valve mounting bores
14	Pressure gauge connection
15	Identical seal rings for ports P and T
16	Seal ring for port X
28	Porting pattern according to ISO 6264-06-09-*-97

Valve mounting screws (separate order)

For reasons of stability, exclusively the following valve mounting screws may be used:

4 x ISO 4762 - M12 x 50 - 10.9-flZn-240h-L

with friction coefficient μtotal = 0.09 … 0.14,

tightening torque MA = 75 Nm ± 10 %,

material no. R913000283

Notice:

The tightening torques are guidelines when using screws with the specified friction coefficients and when using a manual torque wrench (tolerance ± 10 %).

Subplates (separate order) with porting pattern according to ISO 6264-06-09-*-97 see data sheet 45100.

NG25

Dimensions in mm


Required surface quality of the valve contact surface

1	Name plate
2	Port X for remote control, optional
3	Y port for pilot oil return, external
4	Adjustment type "1"
5	Adjustment type "2"
6	Adjustment type "3"
7	Adjustment type "7"
8	Lock nut SW22, tightening torque MA = 10±5 Nm
9	Hexagon SW10
10	Hexagon SW30, tightening torque for screw-in MA = 50 Nm
11	Space required to remove the key
12	Locating pin
13	Valve mounting bores
14	Pressure gauge connection
15	Identical seal rings for ports P and T
16	Seal ring for port X
29	Porting pattern according to ISO 6264-08-13-*-97

Valve mounting screws (separate order)

For reasons of stability, exclusively the following valve mounting screws may be used:

4 x ISO 4762 - M16 x 50 - 10.9-flZn-240h-L

with friction coefficient μtotal = 0.09 … 0.14,

tightening torque MA = 185 Nm ± 10 %,

material no. R913000378

Notice:

The tightening torques are guidelines when using screws with the specified friction coefficients and when using a manual torque wrench (tolerance ± 10 %).

Subplates (separate order) with porting pattern according to ISO 6264-08-13-*-97, see data sheet 45100.

Threaded connection

Dimensions in mm

1	Name plate
2	Port X for remote control, optional
3	Y port for pilot oil return, external
4	Adjustment type "1"
5	Adjustment type "2"
6	Adjustment type "3"
7	Adjustment type "7"
8	Lock nut SW22, tightening torque MA = 10±5 Nm
9	Hexagon SW10
10	Hexagon SW30, tightening torque MA = 50 Nm
11	Space required to remove the key
17	Grub screw is omitted with internal pilot oil return
18	Directional spool valve NG6 (data sheet 23178)
19	Mating connector without circuitry (separate order)
20	Mating connector with circuitry (separate order)
21	Dimension for valve without manual override
22	Dimension for valve with manual override "N"
23	Dimension for valve with concealed manual override "N9"
24	Housing for version "W“
25	Space required to remove the mating connector
26	Valve contact surface; port A is not bored
27	Space required to remove the solenoid coil

Version	D1	ØD2
Version		mm
DB.10.G	G1/2	34
DB.15.G	G3/4	42
DB.20.G	G1	47

Mounting cavity

Version "XY" and type-examination tested safety valves version "Y…E"

Dimensions in mm

1)	Installation depth


Required surface quality of the valve contact surface

37	Bore X, Y and T optionally at the circumference for version "XY" Bore T optionally at the circumference for version "Y" (no separate bore Y required; pilot oil return via bore T)
38	Depth of fit
39	Bore Ø2.5 mm is only to be bored if required
40	Port X does not have to be bored for type-examination tested safety valves version "Y…E" as it does not have any function!

Version “Y”

Dimensions in mm

1)	Installation depth


Required surface quality of the valve contact surface

37	Bore X, Y and T optionally at the circumference for version "XY" Bore T optionally at the circumference for version "Y" (no separate bore Y required; pilot oil return via bore T)
38	Depth of fit

The unloading function (directional valve function with version "W") must not be used for safety functions! Hydraulic counter pressures in port T with internal pilot oil return and/or port Y with external pilot oil return add 1:1 to the response pressure of the valve set at the pilot control.

Example:

Pressure adjustment of the valve due to spring preloading (item 7 see product description) in the pilot control valve/adjustment type

pSpring = 200 bar

Hydraulic counter pressure in port T with internal pilot oil return phydraulic = 50 bar

=> response pressure = pSpring + phydraulic = 250 bar

Mating connectors for valves with connector “K4”, without circuitry, standard

3P Z4

Mating connectors for valves with connector “K4”, without circuitry, standard

3P Z4

For valves with connector “K4” according to EN 175301-803 and ISO 4400, 2-pole + PE, “large cubic connector” Mating connectors for valves with one or two solenoids (individual connection)

Data sheet

Spare parts & repair

Mating connectors for valves with connector “K4”, with indicator light

3P Z5L

Mating connectors for valves with connector “K4”, with indicator light

3P Z5L

For valves with connector “K4” according to EN 175301-803 and ISO 4400, 2-pole + PE, “large cubic connector” Mating connectors for valves with one or two solenoids (individual connection)

Data sheet

Spare parts & repair

DB20G3-4X/350/12 W65

Manufacturer: Bosch Rexroth

Material #: R978871023

Model : DB20G3-4X/350/12 W65

More are expected on June 9, 2025

This product is eligible for factory repair.

general

hydraulic

(measured with HLP46, ϑOil = 40 ±5 °C)

Inlet pressure dependent on the flow

Subplate mounting

Minimum set pressure and circulation pressure dependent on the flow 1) Standard version

Minimum set pressure and circulation pressure dependent on the flow 1) Version “U”

Threaded connection

Minimum set pressure and circulation pressure dependent on the flow 1) Standard version

Minimum set pressure and circulation pressure dependent on the flow 1) Version “U”

Type DB…–…

Type DB…X…

Type DB…Y…

Type DB…XY…

Subplate mounting

Size 10

NG25

Threaded connection

Mounting cavity

Version "XY" and type-examination tested safety valves version "Y…E"

Version “Y”

Related Products

Information

Account

Minimum set pressure and circulation pressure dependent on the flow 1)
Standard version

Minimum set pressure and circulation pressure dependent on the flow 1)
Version “U”

Minimum set pressure and circulation pressure dependent on the flow 1)
Standard version

Minimum set pressure and circulation pressure dependent on the flow 1)
Version “U”