Bosch Rexroth M4-12 Operating instructions

Repair manual
RE 64276-01-R/10.2017
Replaces: 10.2014
English
Load sensing control block
M4-12
Basic document

© BoschRexrothAG2017. All rights reserved,
also regarding any disposal, exploitation,
reproduction, editing, distribution, as well
as in the event of applications for industrial
property rights. The data specified within 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 information given does
not release the user from the obligation of
own judgment and verification. It must be
remembered that our products are subject to a
natural process of wear and aging.
An example configuration is shown on the title
page. The product delivered may therefore
differ from that shown.
The original repair manual was created in the
German language.

RE 64276-01-R/10.2017, M4-12, Bosch Rexroth AG
3/32Contents
1 About this manual 4
1.1 Validity of the documentation 4
1.2 Required and supplementary documentation 4
1.3 Display of information 5
1.3.1 Safety instructions 5
1.3.2 Symbols 6
1.3.3 Designations 6
1.3.4 Abbreviations 6
2 Safety instructions 7
2.1 About this section 7
2.2 Personnel qualifications 7
2.3 Product-specific safety instructions 8
2.4 Personal protective equipment 11
3 General instructions on damage to property and the product 12
4 Product description 16
4.1 Identification of the product 16
4.2 Connection designation 16
4.3 Flange interface 17
4.4 Control block segments 17
4.4.1 Inlet plate 17
4.4.2 Directional valves M4-12 – general 18
4.4.3 Directional valves M4-12 with purely mechanical actuation 19
4.4.4 Directional valves M4-12 with hydraulic actuation 20
4.4.5 Directional valves M4-12 with electrohydraulic actuation 21
4.4.6 Directional valves M4-12 with on-board electronics 22
4.4.7 Directional valves M4-12 with servohydraulic actuation 23
4.4.8 End plate 23
4.5 Control block versions 24
5 General instructions for assembly 25
5.1 Screw connection for hydraulic connections 25
5.2 Screw connection on the control block segment 25
5.3 Fixing the control block in place 26
6 Testing and re-commissioning 27
7 Fault finding 28
8 Accessories and spare parts 29
8.1 Accessories and spare parts on the Internet 29
8.2 Contact partners for accessories and spare parts 29
Contents

4/32 About this manual
Bosch Rexroth AG, M4-12, RE 64276-01-R/10.2017
1 About this manual
This repair manual is made up of the following parts:
Part 01 Basic document
Part 10 Control block assembly
Part 20 Repairing the directional valve
Part 30 Repairing the electro-proportional pressure relief system
Part 40 Repairing the electronics (EPM2)
Part 41 Repairing the electronics (CPM)
Part 50 Repairing the inlet plate
Part 51 Repairing the inlet plate for safety-related applications
1.1 Validity of the documentation
This documentation applies to the following products:
•Load sensing control block M4-12
This manual is aimed at vehicle manufacturers, assemblers and service technicians,
as well as authorized specialist companies and dealers.
This documentation contains important information on the safe and proper repair of
the control block.
▶ Read this documentation in its entirety and in particular the sections 2 “Safety
instructions” page7 and 3 “General notes on damage to equipment and the
product” on page12 before working with the product.
1.2 Required and supplementary documentation
▶ Only commission the product if the documentation marked with the book
symbol is available to you and you have understood and observed it.
Table 1: Required and supplementary documentation
Title Document number Document type
Control blocks for mobile applications
Contains important information for safely and professionally transporting, installing,
commissioning, servicing and removing the Load sensing control block M4-12.
64025-B Operating
instructions
Load sensing control block M4-12 for safety-related applications
Contains important information for safely and professionally transporting, installing,
commissioning, servicing and removing the Load sensing control block M4-12 for
safety-related applications.
64276-01-B Operating
instructions
Load sensing control block M4-12
Contains the permissible technical data.
64276 Data sheet
Load sensing control block M4-12
Contains the spare parts available to order.
64276-E Spare parts list
Related documents for the assembly and repair can be found in Table 21 on page
25 and can be obtained where necessary via
www.boschrexroth.com/mobile-hydraulics-catalog
Documents relating to the general circuit diagram of the machine are available
from the vehicle manufacturer.

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1.3 Display of information
Standardized safety instructions, symbols, terms and abbreviations are used
throughout this documentation so that you can work quickly and safely with your
product. To give you a better understanding, these are explained in the sections
below.
1.3.1 Safety instructions
This manual includes safety instructions in the sections 2.3 “Product-specific safety
instructions” on page8 and 3 “General notes on damage to equipment and the
product” on page12 , as well as prior to sequences of actions or instructions
where there is a risk of injury or material damage. The measures described to avert
danger must be observed.
Safety instructions are set out as follows:
SIGNAL WORD
Type and source of danger
Consequences of non-compliance
▶ Measures to avert danger
•Warning sign: draws attention to the danger
•Signal word: identifies the degree of danger
•Type and source of the hazard: identifies the type and source of the danger
•Consequences: describes what will happen if the safety instructions are not
complied with
•Precautions: states how the danger can be avoided
Table 2: Hazard classes as defined in ANSI Z535.6
Warning sign, signal word Meaning
DANGER Identifies a dangerous situation that will result in death or
serious injuries if it is not avoided.
WARNING Identifies a dangerous situation that may result in death or
serious injuries if it is not avoided.
CAUTION Identifies a dangerous situation that may result in minor to
moderate injuries if it is not avoided.
NOTE Property damage: The product or the environment may be
damaged.

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Bosch Rexroth AG, M4-12, RE 64276-01-R/10.2017
1.3.2 Symbols
The following symbols indicate information that is not directly relevant to safety but
increases understanding of the manual.
Table 3: Meaning of the symbols
Symbol Meaning
If this information is disregarded, the product cannot be used or operated
to its optimum potential.
▶ Single, independent step
1.
2.
3.
Numbered instruction:
The numbers indicate that the steps must be completed one after the
other.
Black circle with white number:
Markings for better understanding.
White circle with black number: Item or assembly with a reference to the
parts list and to the graphics within a section.
White circle with black letters: Assembly with reference to the parts list
and the graphics within a section.
White circle with black Roman numeral:
Variants
Views
1.3.3 Designations
This documentation uses the following designations:
Table 4: Designations
Designation Meaning
M4-12 Directional valve
KBPS Proportional pressure relief
1.3.4 Abbreviations
This manual uses the following abbreviations:
Table 5: Abbreviations
Abbreviation Meaning
IP Inlet Plate
PRV Pressure Relief Valve
EP End Plate
IPC Individual Pressure Compensator
FDP Fixed Displacement Pump
LS Load Sensing
SOV Shut-Off Valve
VP Variable Pump

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2 Safety instructions
2.1 About this section
Before working on the product, read the appropriate instruction manual thoroughly
and completely. If necessary, request the manual from Rexroth.
2.2 Personnel qualifications
This repair manual is aimed at skilled personnel with specialist knowledge in
hydraulics who have taken part in a service training course at Rexroth.
Skilled personnel are individuals who:
•Have acquired sufficient knowledge through professional training and experience
•Are able to evaluate the work assigned to them
•Can identify potential dangers
•Can implement the measures required in order to eliminate dangers
•Are aware of the potential health risks posed by hydraulic fluids
•Have the necessary knowledge to carry out repair and assembly work
Specialist knowledge of hydraulics means:
•Reading and fully understanding hydraulic diagrams
•Specifically, fully understanding the relationships with regard to the installed safety
devices
•Understanding how hydraulic components work and are put together
Bosch Rexroth offers training support for specialist fields. An overview of the
training contents can be found on the Internet at:
http://www.boschrexroth.com/training.

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Bosch Rexroth AG, M4-12, RE 64276-01-R/10.2017
2.3 Product-specific safety instructions
The following safety instructions apply to section 5 to 7.
WARNING
Danger from suspended loads!
Risk of death or injury, or property damage.
Improper transportation may cause the control block to fall down and result in
injury, e.g. crushing or fractures, or damage to the product.
▶ Make sure that the lifting capacity of the lifting device is sufficient to safely bear
the weight of the control block.
▶ Never stand or put your hands under a suspended load.
▶ Make sure the unit remains stable during transport.
▶ Wear your personal protective equipment (e.g., safety goggles, safety gloves,
suitable working clothes, safety shoes).
▶ Use suitable lifting devices for transportation.
▶ Observe the prescribed position of the lifting strap.
▶ Observe the national laws and regulations on work and health protection and
transportation.
Machine under pressure!
Danger to life or risk of injury, serious injuries when working on machines not shut
down! Risk of property damage.
▶ Turn off the entire system and secure it against being restarted as specified by
the machine manufacturer.
▶ Make sure that all relevant components of the hydraulic system are
depressurized. Please follow the machine manufacturer's instructions.
▶ Note that the hydraulic system may still may be under pressure even after the
pressure supply itself has been disconnected.
▶ Do not disconnect any line connections, ports and components while the control
block is under pressure.
Escaping oil mist!
Risk of explosion and fire, health hazard, risk of environmental pollution.
▶ Depressurize all relevant components of the hydraulic system and repair
theleak.
▶ Only perform welding work when the machine is depressurized.
▶ Keep open flames and ignition sources away from the control block.
▶ If control blocks are located in the vicinity of ignition sources or powerful
thermal radiators, a shield must be erected to ensure that any escaped hydraulic
fluid cannot be ignited, and to protect hose lines from premature aging.
Electrical voltage!
Risk of death or injury from electric shock or risk of property damage!
▶ Always set up the relevant part of the machine so that it is deenergized before
you install the product or when connecting and disconnecting connectors.
▶ Secure the machine against being re-energized.

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WARNING
Restriction of the control function!
Risk of death or injury, or property damage.
Moving parts in control and regulation systems (e.g. control spools) may in certain
circumstances become stuck in an undefined position due to contamination
(e.g.contaminated hydraulic fluid, abrasion or residual dirt from components). The
volume flow of the driven consumer will then no longer follow the commands of the
operator.
▶ Secure the machine against rolling away and unintentional movements
according to the specifications of the machine manufacturer.
▶ Observe the specified cleanliness level of the hydraulic fluid in accordance with
a data sheet.
Risk of pressurized hydraulic fluid leaking or fly-away parts!
Danger to life or risk of injury. If fasteners without sufficient high pressure
resistance are used, they can cause rupturing and leakage of hydraulic fluid and/or
fly-away parts. The ports and fastening threads of the control block are designed
for the specified maximum pressure.
▶ Only ever connect connecting elements and lines that match the ports of the
control block and can resist the intended application conditions (e.g. pressure
level, flow, hydraulic fluid, temperature) with the necessary safety factors.
Faulty power supply!
Danger to life or risk of injury due to uncontrolled valve settings! These settings can
lead to unexpected behavior of the control block.
▶ Always connect the ground connection of the control block to the corresponding
ground system in your installation.
▶ Only ever use a power supply unit with safe separation. Always take into
account your country-specific specifications.

10/32 Safety instructions
Bosch Rexroth AG, M4-12, RE 64276-01-R/10.2017
CAUTION
Risk of injury from sharp edges and rough surfaces!
Risk of injury when working with and transporting the control block, e.g. due to
sharp edges on the valve housing, on threads or attachments.
▶ Wear safety shoes with steel toecaps.
▶ Wear safety gloves and appropriate working clothes to protect against injuries.
Crushing and impact hazard for limbs!
In the gap between the actuation element and the valve housing, you can injure
yourself.
▶ Do not put any parts of your body in the gap between the actuation
element/hand lever and the valve housing.
High noise levels during operation!
Risk of hearing damage or hearing loss!
The noise emission of control blocks depends, among other factors, on the working
pressure and the installation conditions. The sound pressure level may rise above
70 dBA under certain application conditions.
▶ Always wear hearing protection when you are in the vicinity of the running
control block.
Hot surfaces on the control block!
Risk of burns.
▶ Allow the control block to cool down sufficiently before touching it.
▶ Wear heat-resistant protective clothing, e.g., gloves.
Cold surfaces on the control block!
Sticking skin, frostbite by touching the cold valve housing!
▶ Wear personal protective clothing, e.g. cold-resistant gloves.
Improper routing of cables and lines!
Risk of stumbling and property damage. Improper routing of cables and lines can
cause a risk of stumbling as well as damage to equipment and components, e.g.,
lines and connectors tearing.
▶ Always route cables and lines in such a way that no one can trip over them,
that they do not become kinked or twisted, do not rub on edges and do not run
without adequate protection through sharp-edged ducts.
Contact with hydraulic fluid!
Risk of adverse health effects, e.g., eye injury, skin irritation, poisoning from
inhalation.
▶ Avoid contact with hydraulic fluids.
▶ When working with hydraulic fluids, strictly observe the safety instructions
provided by the lubricant manufacturer.
▶ Wear your personal protective equipment (e.g., safety goggles, safety gloves,
suitable working clothes, safety shoes).
▶ Consult a doctor immediately if hydraulic fluid gets in your eyes or bloodstream,
or is swallowed.

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CAUTION
Escaping hydraulic fluid due to machine/system leakage!
Risk of burns and risk of injury due to escaping oil jet.
▶ Depressurize the relevant machine/system part and repair the leak.
▶ Never attempt to block or seal the leak or oil jet with a cloth.
Danger from improper handling!
Risk of slipping. Risk of slipping on wet surfaces when using the control block as a
climbing aid.
▶ Never use the control block for grabbing or climbing.
▶ Check how to safely get on top of the machine.
2.4 Personal protective equipment
The personal protective equipment is the responsibility of the user of the control
block. Observe the safety regulations and provisions in your country.
All pieces of personal protective equipment must be intact.
Bosch Rexroth recommends that personal protective equipment for users of the
product comprises:
•Heat-resistant protective clothing, e.g. safety gloves when working on the control
block
•Safety shoes, safety gloves, safety goggles, hearing protection, and suitable
working clothes for working on the control block

12/32 General instructions on damage to property and the product
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3 General instructions on damage to
property and the product
The warranty only applies to the delivered configuration.
Entitlement to warranty claims is void due to
•incorrect assembly, commissioning and operation,
•improper use,
•removal of tamper-proof caps and seals (e.g. with pressure settings),
•adjustment of the factory settings provided on delivery,
•modifications and extensions,
•opening the valve,
•improper handling,
•Using spare parts that are not original spare parts from Rexroth.
•Only original parts from Rexroth may be used.
•Replace elastic seal elements with new ones after removing.
•The housing and parts must be clean and undamaged.
•Damaged housings and parts may no longer be used.
•Reworking threads is not permissible.
•Reworking holes is not permissible.
•Prevent dirt from entering holes and threads.
•Adhesion forces may act between the flange surfaces during disassembly.
•Remove soiling with a sharpening stone and clean with an oil-soaked cleaning
cloth.
•Surfaces with impressions or traces of wear in the sealing surface may no longer
be used.
•Reworking the sealing surfaces is not permissible.
•Protective braces with hard rubber must be used. Sealing and flange surfaces must
not be damaged.
•Oil-soaked cleaning cloth
•Sharpening stone
•Mechanics' tool
•Torque wrench
•Rexroth repair case
– Assembly-disassembly brushes
– Special socket wrench
– Tool
Housing and parts
Flange surfaces and
sealing surfaces
Vise
Tools required

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The following safety instructions apply for chapters 6 to 14.
NOTICE
Danger from improper handling!
Product can get damaged.
▶ Do not expose the product to excessive mechanical, hydraulic or electric load.
▶ Never grab or climb onto the product.
▶ Do not use sensitive attachments (e.g., actuation elements, sensors, solenoids,
or valves) to transport the control block.
▶ Carefully place the control block onto the contact surface to prevent it from
being damaged and secure it against falling.
▶ Do not place/lay any objects on the product.
▶ Do not set/place the control block onto the actuation elements.
▶ Do not strike sensitive attachments (e.g., actuation elements, sensors,
solenoids, or valves).
▶ Do not strike sealing surfaces (e.g., working ports).
▶ Leave the protective covers on the control block until you connect the lines.
▶ Disconnect all electrical connectors before starting painting operations.
▶ Make certain that the electronic components (e.g., sensors) do not become
electrostatically charged (e.g., during painting operations).
Risk of property damage due to improper lubrication!
Product can get damaged or destroyed.
▶ Always commission the control block with sufficient hydraulic fluid.
▶ When commissioning a machine, make sure that the housing area and the
suction and working lines of the control block are filled with hydraulic fluid and
keep them filled during operation.
Liquids and foreign particles enter due to missing seals and plugs!
Loss of protection class and danger of short circuit!
▶ Prior to installation, make sure that all seals and plug-in connections are tight.
Mixing of hydraulic fluids!
Product can get damaged.
▶ Before installation, remove all fluids from the control block to prevent mixing
with the hydraulic fluid that is used in the machine.
▶ Any mixing of hydraulic fluids from different manufacturers or different types
from the same manufacturer is generally not permitted.

14/32 General instructions on damage to property and the product
Bosch Rexroth AG, M4-12, RE 64276-01-R/10.2017
NOTICE
Contamination of the hydraulic fluid!
The cleanliness of the hydraulic fluid has a considerable impact on the cleanliness
and service life of the hydraulic system. Contamination of the hydraulic fluid can
cause premature wear and malfunctions!
▶ Make sure that the working environment at the installation site is fully free
of dust and foreign substances in order to prevent foreign particles, such as
welding beads or metal cuttings, from getting into the hydraulic lines and
causing product wear or malfunctions. The control block must be installed in a
clean condition.
▶ Use only clean ports, hydraulic lines and attachments (e.g., measuring
equipment).
▶ No contamination may enter the ports when they are sealed.
▶ Before commissioning, make sure that all hydraulic connections are tight and
that all of the seals and plugs are installed correctly to ensure that they are
leak proof and fluids and foreign particles are prevented from penetrating the
product.
▶ Use a suitable filter system to filter hydraulic fluids during filling to minimize
solid impurities and water in the hydraulic system.
Improper cleaning!
Product can get damaged.
▶ Plug all openings with appropriate protective equipment to prevent cleaning
agents from entering the control block.
▶ Never use solvents or corrosive cleaning agents. Clean the control block using
only water and a mild cleaning agent if necessary.
▶ Do not point the high-pressure cleaner at sensitive components, e.g. Rubber
parts (the bellows), electrical connections (solenoids and sensors), and
actuation elements.
▶ Use fibre-free cloths for cleaning.
Environmental pollution due to improper disposal!
Careless disposal of the control block, the hydraulic fluid and the packaging
material can result in environmental pollution!
▶ Dispose of the control block, hydraulic fluid, and packaging in accordance with
the national regulations in your country.
▶ Dispose of the hydraulic fluid in accordance with the applicable safety data
sheet for the hydraulic fluid.
Danger from chemical or corrosive environmental conditions!
Product can get damaged. If the control block is exposed to chemical or corrosive
environmental conditions, such as sea water, fertilizer or road salt, it can result
in corrosion or, in extreme cases, malfunction. Hydraulic fluid can escape if leaks
occur.
▶ Take appropriate steps to protect the control block from chemical or corrosive
environmental conditions.

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NOTICE
Escaping or spilling hydraulic fluid!
Risk of environmental pollution and contamination of ground water.
▶ When draining the hydraulic fluid, always place a drip tray under the control
block.
▶ Use an oil binding agent if hydraulic fluid is spilled.
▶ Dispose of the hydraulic fluid according to the national regulations in your
country.
Danger from hot components!
Nearby products can get damaged. Components which heat up (e.g., solenoids)
can cause damage to nearby products if they are too close during installation.
▶ When installing the control block, check the distances to nearby products to
ensure that they are not damaged.

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Bosch Rexroth AG, M4-12, RE 64276-01-R/10.2017
4 Product description
4.1 Identification of the product
The control block and control block segments must be identified on the type plate.
1 2
8910
3
4
5
6
7
MNR: R90xxxxxxx
SN: XXXX
708AMade in Germany
M4-G12345-20/5M4-12J_W2_MV01
123456789
FD: 12W20
1 Word mark (manufacturer)
2 Material number
3 Production date
4 Serial number
5 Material description
6 Customer material number
7 Area/plant number
8 Installation stamp
9 Inspection stamp
10 Designation of origin
4.2 Connection designation
Table 6: Connections
Designation Port for
AConsumer
BConsumer
LS LS signal
TTank or return
PPump
YTank or pilot oil return
XPilot oil supply
MA, MBMeasuring port or external LS signal
, , Tension rod bolt hole

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4.3 Flange interface
Fig. 1: Flange interface
4.4 Control block segments
The following control block segments are available:
•IP for fixed displacement pump (FDP)
•IP for variable pump (VP)
•Multiple M4-12 directional valves can be arranged.
•The end plate closes off the control block.
4.4.1 Inlet plate
Table 7: Internal functions
Item Designation
Primary pressure relief valve
Pilot oil supply cartridge
Pressure compensator
Fig. 2: Inlet plate for fixed displacement pump
Inlet plate (IP)
Directional valves M4-12
End plate (EP)

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Fig. 3: Inlet plate for variable pump
4.4.2 Directional valves M4-12 – general
Table 8: External connections
Item Designation Information
Valve side A
Valve side B
Service line port
Service line port
Secondary pressure relief valve hole optional
Secondary pressure relief valve hole optional
LS pressure relief valve hole optional
LS pressure relief valve hole optional
LS port optional
LS port optional
Table 9: Internal functions
Item Designation
Shuttle valve
Pressure compensator
Y LS port
X pilot oil port
X pilot oil supply
Fig. 4: Directional valve

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4.4.3 Directional valves M4-12 with purely mechanical actuation
Table 10: External connections
Item Designation
Guide on the pilot spool
Bearing block
Hand lever
Cover, side B, with adjustable stroke limitation and
setting shaft
Table 11: Internal functions
Item Designation
Cover, side A
Cover, side A, with locking unit
Secondary pressure relief valve, not adjustable, or plug
Secondary pressure relief valve, adjustable
Cover for LS components
Cover, side A, with spring centering and stroke limitation

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4.4.4 Directional valves M4-12 with hydraulic actuation
Table 12: External connections
Item Designation
Cover, side B, with adjustable stroke limitation and
setting shaft/hand lever
Hydraulic actuation port A
Hydraulic actuation port B
Proportional pressure relief valve type KBPS
Table 13: Internal functions
Item Designation
Cover, side B, with adjustable stroke limitation
Cover, side A, with adjustable stroke limitation
Secondary pressure relief valve or plug
Plate for electro-proportional pressure relief
Unloading valve
Plate for switchable directional valves