26 576

RE 26 576/02.03
Replaces: 11.99
Pressure reducing valve, direct actuated,
with pressure monitoring
Types DRHD 6 DP and ZDRHD 6 D.
Nominal size 6
Series 4X
Maximum operating pressure 200 bar
Maximum flow 40 L/min Type ZDRHD 6 DP2-4X/200-25K14 with plug-in connector and
type DRHD 6 DP2-4X/200-25K14 with plug-in connector
Overview of contents
Contents Page
Features 1
Ordering details 2
Plug-in connector 2
Symbols 3
Function, section 4
Technical data 5
Electrical connections 5
Characteristic curves 6, 7
Unit dimensions 8
H6218+H6220
Features
– For subplate mounting or as a sandwich plate:
Porting pattern to DIN 24 340 form A,
ISO 4401 and CETOP–RP 121 H,
for subplates see catalogue sheet RE 45 052
(separate order)
– Clamping pressure adjustment and monitoring in one unit
– Common adjustment for clamping and monitoring pressure
– Pressure monitoring optionally either internal or external
at the actuator
– The switching differential between the reduced and
monitoring pressure is adjustable
– Limitation of the minimum settable monitoring or
secondary pressure
© 2003
by Bosch Rexroth AG, Industrial Hydraulics, D-97813 Lohr am Main
All rights reserved. No part of this document may be reproduced or stored, processed, duplicated or circulated using
electronic systems, in any form or by means, without the prior written authorisation of Bosch Rexroth AG. In the event of
contravention of the above provisions, the contravening party is obliged to pay compensation.
.DRHD 6 D. 1/8 RE 26 576/02.03

Ordering details
Subplate mounting = No code
Sandwich plate valve = Z
Pressure reducing valve with
pressure monitoring
Nominal size 6 = 6
Direct actuated = D
Primary pressure in port P (controlled from „P1“) = P
Primary pressure in port P (controlled from „A“) = A 1)
Primary pressure in port P (controlled from „B“) = B 1)
Adjustment element
Rotary knob = 1
Internal hexagon with protective cap = 2
Lockable rotary knob = 3 2)
Series 40 to 49 = 4X
(40 to 49: unchanged installation and connection dimensions)
Permissible operating pressure 200 bar
Pressure stage
= 200
Maximum secondary pressure 25 bar = 25
Maximum secondary pressure 50 bar = 50
Maximum secondary pressure 100 bar = 100
1) Only with sandwich plate valves
2) H-key to material no. R900008158 is included within the scope of supply.
3) Plug-in connector has to be separately ordered (see below).
DRHD 6 D 4X 200 K14
RE 26 576/02.03 2/8 .DRHD 6 D.
*
Further details
in clear text
No code = NBR seals
(other seals on
request)
Attention!
The compatibility of the
seals and pressure fluid
has to be taken into account!
Electrical connections
K14 3) = Individual connection;
with component plug DIN EN 175 301-803,
without plug-in connector
No code = Pressure connection
(for reduced and switching pressure), internal
X = Pressure connection, external
Y = Pressure connections (A; B),
with shuttle valve
(only with sandwich plate valves)
Ordering details: plug-in connector to DIN EN 175 301-803 and ISO 4400 for component plug "K14"
Further plugin
connectors
see
RE 08 006
Material no.
With circuitry (indicator light)
Colour Without circuitry 6 … 14 V 16 … 30 V 36 … 60 V 90 … 130 V 180 … 240 V
Black R900001260 R900545844 R900545845 R900545846 R900545847 R900545848

Symbols ( 1 = component side, 2 = subplate side)
Subplate mounting
Type DRHD 6 DP… Type DRHD 6 DP…X
P A 2 B
Sandwich plate valve
Type ZDRHD 6 DA…
X
M
P A 2 B
Type ZDRHD 6 DP…
P A 2 B
1
1
1
1
P A 2 B
T X
T
T
T
P A 2 B
P A 2 B
.DRHD 6 D. 3/8 RE 26 576/02.03 576/11.99
X
M
Type ZDRHD 6 DB…
Type ZDRHD 6 DP…X Type ZDRHD 6 DP…Y
X
Port T has to be drained at zero pressure!
P A B
1
1
1
2
T
T
T
X
M

Function, section
The valve type .DRHD 6 D. is a direct actuated 3-way pressure reducing
valve with pressure limitation of the secondary circuit and integrated
pressure monitoring. It is used to reduce the system pressure and is
optionally available with internal or external pressure monitoring, as
well as a shuttle valve plate for monitoring ports A or B.
The pressure reducing valve basically comprises of the housing (1), a
pressure reducing spool (2), a pressure monitoring spool (3), two
compression springs (4 and 5) as well as a pressure adjustment
element (6). The conversion from the sandwich plate version to the
subplate mounting version is via a conversion plate (7) P1 to A1.
In the initial position the valve is open; pressure fluid flows from port
P2 to port P1. The pressure in port P1 is, at the same time, applied to
the pressure reducing spool (2) and the pressure monitoring spool
(3) via the control line (8), this pressure acts against the springs (4
and 5). If the pressure in port P1 rises above the value set at the
adjustment element (6), the pressure reducing spool (2) moves against
the compression spring (4) into the control position and thereby holds
the set pressure in port P1 constant. The pressure reduction results
from pressure being applied to the pressure reducing spool (2) from
port P1.
9
Type ZDRHD 6 DP3…
7
1
8
B P A T
B1 P1 A1 T1
X B2 P2 A2 T2
3 2 12
The secondary pressure which is to be monitored also acts via control
line (8) on the ring area of the pressure monitoring spool (3) (common
pressure chamber for spools (2) and (3)).
At a defined pressure, which lies below the secondary pressure, the
switch (9) is actuated and an electrical signal is given. This signal
can, for example, be used to switch on a chuck as soon as the minimum
(switch actuation pressure) required pressure is reached. If the
secondary pressure falls below the minimum pressure the chuck will
be automatically switched off.
The minimum settable monitoring or secondary pressure is adjustable
via screw (10).
The switching differential between the minimum
clamping pressure and the working pressure can be
optimally adjusted via the spindle (11).
If the pressure in port P1 continues to increase due to outside forces
at the actuator, then the pressure reducing spool (2) moves further
against the compression spring (4).
Due to this port P1, via control land (12) at the pressure reducing
spool (2) and housing (1) is connection to port T.
Pressure fluid continues to flow to the reservoir until the pressure no
longer increases (secondary pressure limitation).
The oil drain from the spring chamber (13) is always via port T.
Type DRHD 6 DP3…
(with conversion plate for subplate mounting)
4 13 5 11 10 6
RE 26 576/02.03 576/11.99
4/8 .DRHD 6 D.

Technical data (for applications outside these parameters, please consult us!)
General
Installation optional
Weight „No code“ „X“ „Y“
Hydraulic
1) The cleanliness class stated for the components must be
adhered too in hydraulic systems. Effective filtration prevents
faults from occurring and at the same time increases the
component service life.
For the selection of filters see catalogue sheets
RE 50 070, RE 50 076 and RE 50 081.
Electrical connections
– Subplate mounting kg 2.2 3.0 –
– Sandwich plate valve kg 1.8 2.6 2.6
Maximum operating pressure
Maximum secondary pressure
Port P bar 200
– Subplate mounting: Port A bar 100
– Sandwich plate valve:
Maximum permissible pressure in port T
Port P1 bar 100
– Subplate mounting bar 2
– Sandwich plate valve bar 2
Maximum flow L/min 40
Pressure fluid Mineral oil (HL, HLP) to DIN 51 524;
Fast bio-degradable pressure fluids to
VDMA 24 568 (also see RE 90 221); HETG (rape seed oil);
other pressure fluids on request
Pressure fluid temperature range °C –30 to +80 (with NBR seals)
Viscosity range mm2 /s 10 to 800
Cleanliness class to ISO code Maximum permissible degree of contamination of the pressure
fluid is to ISO 4406 (C) class 20/18/15 1)
Electrical
Electrical connection to DIN EN 175 301-803 plug connector 3-pin + SL (PE)
Maximum connection cross-section mm2 1.5
Contact loading – AC up to 250 V; 5A
– DC up to 50 V; 1A
up to 250 V; 0.02A
Connections at plug connector
4
1 2
.DRHD 6 D. 5/8 RE 26 576/02.03

Characteristic curves (measured with HLP46, ϑ oil = 40 °C ± 5 °C)
Secondary pressure in bar →
Differential pressure in bar →
pA-qV-characteristic curves
120
100
80
60
40
20
0 40 30 20 10 0 10 20 30 40
30
20
10
Type DRHD 6 DP (subplate mounting) Type ZDRHD 6 D. (sandwich plate valve)
Flow in L/min →
A to T P to A
1
2
pA-qV-characteristic curves
120
∆p-q V -characteristic curves ∆p-q V -characteristic curves
RE 26 576/02.03 6/8 .DRHD 6 D.
100
80
60
40
20
0 40 30 20 10 0 10 20 30 40
0 10 20 30 40 0 10 20 30 40
Flow in L/min → Flow in L/min →
1 P to A
3 P2 to P1
2 A to T
4 P1 to T
30
20
10
Flow in L/min →
P1 to T P2 to P1
The characteristic curves are valid for an output pressure p T = zero over the entire flow range!
Secondary pressure in bar →
Differential pressure in bar →
4
3

Pressure monitoring
Monitored pressure in bar →
Monitored pressure in bar →
25
22
18
14
10
100
90
80
70
60
50
40
30
20
10
6
2
0
0
Pressure stage 25
Signal: clamping
2 6 10 14 18 22 25
Clamping pressure in bar →
Pressure stage 100
Signal: clamping
Clamping pressure
Signal: de-clamp
Clamping pressure
Signal: de-clamp
10 20 30 40 50 60 70 80 90 100
Clamping pressure in bar →
Adjustable switching differential
Adjustable switching differential
Pressure stage 50
50
45 Signal: clamping
40
35
30
.DRHD 6 D. 7/8 RE 26 576/02.03
Monitored pressure in bar →
25
20
15
10
5
0
Clamping pressure
Signal: de-clamp
5 10 15 20 25 30 35 40 45 50
Clamping pressure in bar →
Adjustable switching differential
Note:
For readjusting the switching differential by means of the spindle
(11), see sectional drawing on page 4:
• Turning in the clockwise direction → switching differential
increases
• Turning in the anti-clockwise direction → switching differential
becomes smaller

Unit dimensions (Dimensions in mm)
13
15
18 25
45
Ø35
0 1 2
9
8
7; 9
130
1 Name plate
2 Plug-in connector without circuitry 1)
3 Plug-in connector with circuitry 1)
Ø39
4 Space required to remove the plug-in
connector
5 Shuttle valve (only with sandwich plate
valve, version „Y“)
6 Pressure connection plate (only with
version „X“)
7 Adjustment element „1“
8 Adjustment element „2“
9 Adjustment element „3“
10 Seal ring for connection X
11 Identical seal rings
for ports A2, B2, T2, P2
12 Internal hexagon A/F 6
Bosch Rexroth AG
Industrial Hydraulics
D-97813 Lohr am Main
Zum Eisengießer 1 • D-97816 Lohr am Main
Telefon 0 93 52 / 18-0
Telefax 0 93 52 / 18-23 58 • Telex 6 89 418-0
eMail documentation@boschrexroth.de
Internet www.boschrexroth.de
105
5
6
G 1/4
102
14
40
40
Bosch Rexroth Limited
A2 B2 X
11 10 2
M
262
31
237
Cromwell Road, St Neots,
Cambs, PE19 2ES
Tel: 0 14 80/22 32 56
Fax: 0 14 80/21 90 52
eMail: info@boschrexroth.co.uk
P A B T
A2 B2
A2 B2
0,01/100mm
R max4
The data specified above only serves to describe
the product. No statements concerning a certain
condition or suitability for a certain application
can be derived from our information.
The details stated do not release you from the
responsibility for carrying out your own
assessment and verification. It must be
remembered that our products are subject to a
natural process of wear and ageing.
RE 26 576/02.03 8/8 .DRHD 6 D.
A1
A1 B1
12 1
22 40,5
T1
65
62
70
11,5
B1
P1
15
X
17
X
X
40
20
M
X
3
G 1/4
G 1/4
11
Pg 11
Pg 11
36
42
12
12
Required surface finish of
mating piece
8
83
16
13 Hexagon A/F 27
16 Porting pattern to DIN 24 340 form A,
14 Conversion plate for subplate mounting ISO 4401 and CETOP–RP 121 H,
15 Space required to remove the key
Valve fixing screws
M5 DIN 912-10.9
tightening torque MA = 8.9 Nm,
must be ordered separately.
1) must be ordered separately,
see page 2.
31,75 0,75
Ø38
4
4