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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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.

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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.