Bosch Rexroth A4VG 35 Series User manual

Instruction manual
RE 92035-01-B/04.2018
Replaces: –.–
English
Axial piston variable pump
A4VG
Series 35

© Bosch Rexroth AG 2018. 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.
The cover shows an example application.
The product delivered may differ from the
image on the cover.
The original instruction manual was created in
the German language.

Contents 3/64
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1 About this documentation 5
1.1 Applicability 5
1.2 Required and supplementary documentation 5
1.3 Representation of information 6
1.3.1 Safety instructions 6
1.3.2 Symbols 7
1.3.3 Designations 7
1.3.4 Abbreviations 8
2 Safety instructions 9
2.1 About this chapter 9
2.2 Intended use 9
2.3 Improper use 9
2.4 Personnel qualifications 10
2.5 General safety instructions 11
2.6 Product-specific safety instructions 12
2.7 Personal protective equipment 15
3 General instructions regarding property and product damage 16
4 Scope of delivery 19
5 About this product 20
5.1 Performance description 20
5.2 Product description 20
5.2.1 Axial piston unit layout 20
5.2.2 Functional description 21
5.3 Bypass function 22
5.3.1 Activating and deactivating the bypass function 22
5.4 Product identification 24
6 Transport and storage 25
6.1 Transporting the axial piston unit 25
6.1.1 Transporting by hand 25
6.1.2 Transporting with a lifting device 25
6.2 Storing the axial piston unit 28
7 Installation 30
7.1 Unpacking 30
7.2 Installation conditions 30
7.3 Installation position 31
7.3.1 Below-reservoir installation (standard) 32
7.3.2 Above-reservoir installation 33
Contents

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7.4 Installing the axial piston unit 34
7.4.1 Preparation 34
7.4.2 Dimensions 34
7.4.3 General instructions 34
7.4.4 Installation with a clutch 35
7.4.5 Installation on a gearbox 36
7.4.6 Installation with cardan shaft 36
7.4.7 Completing installation 37
7.4.8 Hydraulically connecting the axial piston unit 38
7.4.9 Electrically connecting the axial piston unit 42
7.5 Performing flushing cycle 43
8 Commissioning 44
8.1 Initial commissioning 44
8.1.1 Filling the axial piston unit 45
8.1.2 Testing the hydraulic fluid supply 46
8.1.3 Performing a functional test 46
8.2 Running-in phase 47
8.3 Recommissioning after standstill 47
9 Operation 48
10 Maintenance and repair 49
10.1 Cleaning and care 49
10.2 Inspection 50
10.3 Maintenance 50
10.4 Repair 51
10.5 Spare parts 51
11 Removal and replacement 52
11.1 Required tools 52
11.2 Preparing for removal 52
11.3 Removal 52
11.4 Preparing the components for storage or further use 52
12 Disposal 53
13 Extension and conversion 54
14 Troubleshooting 55
14.1 How to proceed for troubleshooting 55
14.2 Malfunction table 56
15 Technical data 60
16 Alphabetical index 61
Contents

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1 About this documentation
1.1 Applicability
This documentation applies to the following products:
•Axial piston variable pump A4VG Series 35
This manual is intended for machine/system manufacturers, assemblers and service
engineers.
It contains important information on the safe and proper transport, installation,
commissioning, operation, maintenance, removal and simple troubleshooting of the
axial piston unit.
▶ Read this documentation completely, in particular Chapter 2 “Safety instructions”
on page 9 and Chapter 3 “General instructions regarding property and
product damage” on page 16 before you start work with the axial piston unit.
1.2 Required and supplementary documentation
▶ Only commission the axial piston unit 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
Order confirmation
Contains the order-related technical data for your axial piston variable
pump A4VG.
– Order confirmation
Installation drawing
Contains the outer dimensions, all ports and the hydraulic circuit diagram
for your axial piston variable pump A4VG.
Please request the
installation drawing
from your contact at
Bosch Rexroth.
Installation drawing
Axial piston variable pump A4VG
Contains the permissible technical data.
92035 Data sheet
Hydraulic fluids based on mineral oils and related hydrocarbons
Describes the requirements on a hydraulic fluid based on mineral oil and
related hydrocarbons for operation with Rexroth hydraulic components, and
assists you in selecting a hydraulic fluid for your system.
90220 Data sheet
Environmentally acceptable hydraulic fluids
Describes the requirements on an environmentally acceptable hydraulic fluid
for operation with Rexroth hydraulic components and assists you in selecting
a hydraulic fluid for your hydraulic system.
90221 Data sheet
Fire-resistant, water-free hydraulic fluids (HFDR/HFDU)
Describes the requirements on fire-resistant, anhydrous hydraulic fluids
(HFDR/HFDU) for operation with Rexroth hydraulic components and assists
you in selecting a hydraulic fluid for your hydraulic system.
90222 Data sheet
Axial piston units for operation with fire-resistant hydraulic fluids –
anhydrous and hydrous (HFDR, HFDU, HFA, HFB, HFC)
Describes the requirements on fire-resistant, anhydrous and hydrous
hydraulic fluids (HFDR, HFDU, HFA, HFB, HFC) and contains the technical
data for operation with Rexroth hydraulic components.
90225 Data sheet

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Table 1: Required and supplementary documentation
Title Document number Document type
Component class: 92003-CC-0011_ETPump
The component class specification explains what data is available, how this
data was obtained, and what else should be observed.
92003-CC-0011_ETPump Component class
specification
BODAS-drive eDA application software
BODAS-drive eDA is a software solution integrated in the Rexroth SRC-
eDA1/31 control unit for controlling the hydrostatic drive train in wheeled
vehicles.
95315 Data sheet
Information on the use of hydrostatic drives at low temperatures
Contains additional information on the use of Rexroth axial piston units at
low temperatures.
90300-03-B Manual
Storage and preservation of axial piston units
Contains additional information on storage and preservation.
90312 Data sheet
1.3 Representation 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. For clarification, they are explained in the sections below.
1.3.1 Safety instructions
This documentation includes safety instructions in chapter2.6 “Product-specific
safety instructions” on page12 and in chapter3 “General instructions regarding
property and product damage” on page16 and before a sequence of actions or
an instruction for action involving a risk of personal injury or damage to property.
Always follow the instructions on avoiding the dangers associated with the use of
this product.
Safety instructions are set out as follows:
SIGNAL WORD
Type and source of danger!
Consequences of noncompliance
▶ Measures to prevent danger
•Warning sign: draws attention to the danger
•Signal word: identifies the degree of the danger
•Type and source of danger: indicates the type and source of the danger
•Consequences: describes what occurs if safety instructions are not complied with
•Precautions: states how the danger can be avoided

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Table 2: Danger classes as defined in ANSI Z535.6
Warning sign, signal word Meaning
DANGER Identifies a dangerous situation that will result in death or
serious injury if it is not avoided.
WARNING Identifies a dangerous situation that may result in death or
serious injury if it is not avoided.
CAUTION Identifies a dangerous situation that may result in minor to
moderate injury if it is not avoided.
NOTICE Property damage: The product or the environment may get
damaged.
1.3.2 Symbols
The following symbols indicate information that is not safety-relevant but increases
understanding of the documentation.
Table 3: Meaning of symbols
Symbol Meaning
If this information is disregarded, the product cannot be used and/or
operated to its full extent.
▶ Single, independent action
1.
2.
3.
Numbered instruction:
The numbers indicate that the actions must be completed in order.
1.3.3 Designations
This documentation uses the following designations:
Table 4: Designations
Designation Meaning
A4VG Axial piston variable pump and closed circuit
Threaded plug Metal screw, pressure-resistant
Protective plug Made out of plastic, not pressure-resistant, only for transportation
As umbrella term for “axial piston variable pump A4VG” the designation “axial piston
unit” will be used in the following.

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1.3.4 Abbreviations
This manual uses the following abbreviations:
Table 5: Abbreviations
Abbreviation Meaning
ATEX EC directive on explosion protection (Atmosphère explosible)
DIN Deutsches Institut für Normung (German Institute for Standardization)
ET Electric control, direct-operated with two pressure reducing valves
(PRV)
ISO International Organization for Standardization
RE Rexroth document in the English language
VDI2230 Standard for the systematic calculation of heavy-duty thread connections
and cylindrical screw joints from the VDI (VereinDeutscherIngenieure -
Association of German Engineers)

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2 Safety instructions
2.1 About this chapter
The axial piston unit has been manufactured to generally accepted engineering
standards. There is still, however, a risk of personal injury or property damage if this
chapter and the safety instructions in this documentation are not observed.
▶ Read this documentation completely and thoroughly before working with the axial
piston unit.
▶ Keep it in a location where it is accessible to all users at all times.
▶ Always include the required documentation when you pass the axial piston unit
on to third parties.
2.2 Intended use
Axial piston units are hydraulic components, meaning that in their application area
they are classified neither as complete nor as partly completed machinery as defined
in the EC Machinery Directive (2006/42/EC). The component is exclusively intended
to form partly completed machinery or complete machinery together with other
components. The component may only be commissioned after it has been installed
in the machine/system for which it is intended and the safety of the entire system
has been established in accordance with the Machinery Directive.
This product is intended for the following use:
The axial piston unit is only approved as a pump for hydrostatic drives in closed
circuit.
▶ Observe the technical data, the application and operating conditions and
the performance limits as specified in data sheet92035 and in the order
confirmation. Information about approved hydraulic fluids can be found in data
sheet 92035.
The axial piston unit is only intended for commercial use and not for private use.
Intended use includes having fully read and understood this documentation,
especially Chapter 2 “Safety instructions” on page 9.
2.3 Improper use
Any use other than that described as intended use is considered improper.
Bosch Rexroth AG is not liable for damages resulting from improper use.
The user is solely responsible for any risks arising from improper use.
The following foreseeable misuses are also considered improper (this list is not
exhaustive):
•Use outside the operating parameters approved in the data sheet or in the order
confirmation (unless specifically approved by the customer)
•Use of non-approved fluids, e.g. water or polyurethane components
•Changes to factory settings by unauthorized persons
•Use of add-ons (e.g., control unit, valves) not in combination with the specified
Rexroth components
•Use of the axial piston unit with assembled parts under water at a depth of
more than 10meters without the necessary additional measures, e.g. pressure
equalization. Units with electrical components (e.g. sensors) generally cannot
come into contact with water.

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•Use of the axial piston unit under a continuous pressure differential between
housing and ambient pressure greater than 2bar, with the ambient pressure always
lower than the case pressure. Momentary (t<0.1s) pressure peaks of up to 10bar
are allowed, but no more than 1000 pressure peaks over the entire service life.
Beyond this, the maximum permissible case pressure specified in the data sheet
should not be exceeded.
•Use of the axial piston unit in explosive environments unless the component
or machine/system has been certified as compliant with the ATEX
directive 2014/34/EC
•Use of the axial piston unit in a corrosive atmosphere
•Use of the axial piston unit in aircraft or spacecraft
2.4 Personnel qualifications
The activities described in this manual require a basic understanding of mechanics,
electricity and hydraulics, as well as familiarity with associated technical terms.
For transporting and handling the product, additional familiarity with the use of
lifting devices and lifting accessories is required. In order to ensure safe use, these
activities should only be performed by skilled personnel or an instructed person
under the direction and supervision of a skilled person.
Qualified personnel refers to persons who possess the professional training,
knowledge and experience, as well as the understanding of the regulations relevant
to the work to be done that are necessary to recognize possible hazards and take the
appropriate safety measures. Qualified personnel must follow the rules relevant to
their field and have the necessary hydraulics expert knowledge.
Hydraulic expert knowledge includes:
•Being able to read and fully understand hydraulic circuit diagrams
•In particular, fully understanding the relationships with regard to safety devices
•Understanding how hydraulic components work and are put together.
Bosch Rexroth offers training support for specialized fields. An overview of the
training contents can be found online at: www.boschrexroth.com/training.

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2.5 General safety instructions
•Observe the applicable accident prevention and environmental protection
regulations.
•Observe the safety regulations and provisions of the country in which the product
is used/operated.
•Use Rexroth products only when they are in good working order.
•Observe all notices on the product.
•Do not install, operate, remove or maintain Rexroth products if under the influence
of alcohol, drugs or medication that may affect your reaction time.
•Only use genuine Rexroth accessories and spare parts to ensure there is no hazard
to persons due to unsuitable spare parts.
•Observe the technical data and ambient conditions specified in the product
documentation.
•If unsuitable products are installed or used in applications that are of relevance to
safety, unexpected operating conditions may occur in the application, which could
result in personal injury or property damage. For this reason, only use the product
in safety-relevant applications if this use is expressly indicated and approved in
the product documentation, e.g. in explosion protection applications or in safety-
related parts of a control system (functional safety).
•Only commission the product if it has been determined that the end product
(e.g. machinery or system) in which the Rexroth products are installed complies
with the country-specific provisions, safety regulations and standards for the
application.
•Use tools appropriate for the work being performed and wear appropriate
protective clothing to prevent punctures and cuts (e.g. when removing protective
covers, disassembly).
•There is a risk of entanglement when operating the axial piston unit with a bare
shaft end. Check whether or not your machine requires additional safety measures
for your application. If necessary, make sure that these are properly implemented.
•Depending on the type of control used, electromagnetic effects can be produced
when using solenoids. When a direct current is applied, solenoids do not cause
electromagnetic interference nor is their operation impaired by electromagnetic
interference. Other behavior can result when a modulated direct current
(e.g. PWM signal) is applied. Potential electromagnetic interference for persons
(e.g. persons with a pacemaker) and other components must be tested by the
machine manufacturer.

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2.6 Product-specific safety instructions
The following safety instructions apply to chapters 6 to 14.
WARNING
Danger from excessively high pressure!
Risk of death or injury, or property damage!
Improperly changing the factory pressure settings can result in a pressure increase
beyond the maximum permissible pressure.
Operating the unit above the maximum permissible pressure can cause
components to burst and hydraulic fluid to escape under high pressure.
▶ Changes to the factory settings should only be made by Bosch Rexroth
specialists.
▶ In addition, a pressure relief valve is required in the hydraulic system as a back-
up. If the axial piston unit is equipped with a pressure cut-off and/or a pressure
controller, this is not an adequate back-up against pressure overload.
Danger from suspended loads!
Risk of death or injury, or property damage!
Improper transportation may cause the axial piston unit to fall down and lead to
injuries e.g. crushing or broken bones or damage to the product.
▶ Make sure that the load bearing capacity of the lifting device is sufficient to
safely bear the weight of the axial piston unit.
▶ 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 occupational health and safety,
and transportation.
System/machine under pressure!
Risk of death or serious injury when working on unsecured machines/systems!
Risk of property damage!
▶ Switch off the entire system and secure it against reactivation according to the
parameters provided by the machine/system manufacturer.
▶ Make sure that all relevant components of the hydraulic system are
depressurized. Follow the machine/system manufacturer’s specifications.
▶ 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 as long as the
hydraulic system is under pressure.

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WARNING
Escaping hydraulic fluid mist!
Risk of explosion and fire, health hazard, risk of environmental pollution!
▶ Depressurize the relevant machine/system component and repair the leak.
▶ Only perform welding work when the machine/system is depressurized.
▶ Keep open flames and ignition sources away from the axial piston unit.
▶ If axial piston units 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 injury from electric shock or risk of property damage!
▶ Always disconnect the relevant part of the machine/system before installing the
product or when inserting/removing connectors. Protect the machine/system
against being reactivated.
Danger from unexpected machine movement!
Risk of death or injury! Unintentional or careless actuation of the manual override
of the solenoids can cause unexpected machine movements.
▶ Use the manual override only for functional testing or in the event of technical
malfunctions.
▶ Using the manual override on a permanent basis (e.g. by wedging, blocking) is
not permitted.
▶ The use of the manual override is only permitted with limited technical data
(e.g. 0.25×maximum data).
▶ Check whether or not your machine requires additional safety measures for your
application to avoid unintentional actuation. If necessary, make sure that these
are properly implemented.
▶ Wear suitable protective clothing.
Restriction of control function!
Risk of injury or property damage!
Moving parts in control equipment (e.g.valve spools) can, under certain
circumstances, get stuck in position as a result of contamination (e.g.impure
hydraulic fluid, abrasion, or residual dirt from components). As a result, the
hydraulic fluid flow and the build-up of torque in the axial piston unit can no longer
meet the operator's specifications. Even the use of various filter elements (external
or internal flow filtration) will not rule out a fault but merely reduce the risk.
▶ Check whether your application requires that remedial measures be taken on
your machine in order to bring the driven consumer into a safe position
(e.g. safe stop).
▶ If necessary, make sure that these are properly implemented.

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WARNING
Risk of pressurized hydraulic fluid leaking or flying components!
Risk of death or injury! If connecting elements without sufficient high pressure
resistance are used, they can cause rupturing and leakage of hydraulic fluid and/
or flying components. The ports and fastening threads of the axial piston unit are
designed for the specified maximum pressure.
▶ Only ever connect connecting elements and lines that match the ports of the
axial piston unit and can resist the intended application conditions
(e.g. pressure level, flow, hydraulic fluid, temperature) with the necessary
safety factors.
CAUTION
High noise development during operation!
Risk of hearing damage or hearing loss!
The noise emission of axial piston units depends on, among other factors,
rotational speed, working pressure and installation conditions. The sound pressure
level may rise above 70dB(A) in certain application conditions.
▶ Always wear hearing protection in the vicinity of the operating axial piston unit.
Hot surfaces on axial piston unit!
Risk of burning!
▶ Allow the axial piston unit to cool down sufficiently before touching it.
▶ Wear heat-resistant protective clothing, e.g. gloves.
Improper cable and line routing!
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.,
due to lines and connectors being torn off.
▶ Always lay 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, toxication 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 leakage from machine/system components!
Risk of burning and risk of injury due to escaping hydraulic fluid jet!
▶ Depressurize the relevant machine/system component and repair the leak.
▶ Never attempt to block or seal the leak or hydraulic fluid jet with a cloth.
Danger from improper handling!
Slip hazard! Risk of slipping on wet surfaces when climbing on the axial piston unit.
▶ Never grab or climb onto the axial piston unit.
▶ Check how to safely get on top of the machine/system.
2.7 Personal protective equipment
Personal protective equipment is the responsibility of the user of the axial piston
unit. Observe the safety regulations in your country.
All pieces of personal protective equipment should be intact.

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3 General instructions regarding property
and product damage
The following notices apply to chapters 6 to 14.
NOTICE
Danger from improper handling!
Product can be damaged!
▶ Do not expose the product to excessive mechanical loads.
▶ Never grab or climb onto the product.
▶ Do not place/lay any objects on the product.
▶ Do not strike the drive shaft of the axial piston unit.
▶ Do not set/place the axial piston unit on the drive shaft or assembled parts.
▶ Do not strike assembled parts (e.g. sensors or valves).
▶ Do not strike sealing surfaces (e.g. working ports).
▶ Leave the protective covers on the axial piston unit until you connect the lines.
▶ Disconnect all electrical connectors before arc welding or painting.
▶ Make sure that the electronic components (e.g. sensors) do not build up
electrostatic charges (e.g. during painting).
Risk of property damage due to inadequate lubrication!
Product can be damaged or destroyed!
▶ Never operate the axial piston unit with insufficient hydraulic fluid. Specifically,
make sure that the rotary group has sufficient lubrication.
▶ When commissioning a machine/system, make sure that the housing area and
the working lines of the axial piston unit are filled with hydraulic fluid and
remain filled during operation.
▶ Check the hydraulic fluid level in the housing area regularly and recommission,
if necessary. For above-reservoir installation, the housing area may drain out
through the drain line after prolonged standstill periods (air enters through the
shaft seal) or through the working line (gap leakage). This means the bearings
are insufficiently lubricated when the system is turned on.
▶ Make sure that the suction line is always filled with hydraulic fluid during
commissioning and operation.
Mixing of hydraulic fluids!
Product can be damaged!
▶ Before installation, remove all fluids from the axial piston unit to prevent mixing
with the hydraulic fluid used in the machine/system.
▶ Never mix hydraulic fluids from different manufacturers or different types from
the same manufacturer.

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NOTICE
Contamination of 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 completely
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 axial piston unit should be clean
when installed.
▶ Use only clean ports, hydraulic lines and assembled parts (e.g. measuring
devices).
▶ Do not allow any contamination into the ports when they are being plugged.
▶ Before commissioning, make sure that all hydraulic connections are tight and
that all of the seals and plug-in connections are installed correctly to ensure
that they are leak-proof, and fluids and foreign particles cannot enter into the
product.
▶ Use a suitable filter system to filter hydraulic fluid during filling to minimize solid
particle contamination and water in the hydraulic system.
Improper cleaning!
Product can be damaged!
▶ Close all openings with appropriate protective covers in order to prevent
cleaning agents from entering the hydraulic system.
▶ Never use solvents or corrosive cleaning agents. Use only water and, if
necessary, a mild cleaning agent to clean the axial piston unit.
▶ Do not point a high-pressure cleaner at sensitive components, e.g. shaft seal,
electrical connections and components.
▶ Use fiber-free cloths for cleaning.
Environmental pollution due to improper disposal!
Careless disposal of the axial piston unit and its assembled parts, the hydraulic
fluid and the packaging material can result in environmental pollution!
▶ Dispose of the axial piston unit, hydraulic fluid and packaging in accordance
with the 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 be damaged! If the axial piston unit 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 axial piston unit 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!
▶ Always place a drip tray under the axial piston unit when adding and draining
the hydraulic fluid.
▶ Use a suitable binding agent if hydraulic fluid is spilled.
▶ Observe the safety data sheet for the hydraulic fluid and the specifications
provided by the system manufacturer.
Danger from hot components!
Nearby products can be damaged! Components that heat up (e.g. solenoids)
can cause damage to nearby products if they are too close.
▶ When installing the axial piston unit, check the distances to nearby products
to ensure that they are not damaged.
The warranty only applies to the machine as delivered.
The warranty will be voided if the product is incorrectly installed, commissioned
or operated, or if it is used or handled improperly.

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4 Scope of delivery
1
2
2
4
3
Fig. 1: Axial piston unit
Scope of delivery includes the following:
•Axial piston unit as per order confirmation
The following parts come assembled on the unit:
•Protective covers(1)
•Protective plug/threaded plug(2)
•Protective covers for sensors and connectors (3)
•For version with through drive, metallic protective cover and mounting bolts(4)

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5 About this product
5.1 Performance description
The axial piston variable pump generates, controls and regulates a hydraulic-fluid
flow. It is designed for mobile applications such as construction machinery.
Refer to data sheet 92035 and the order confirmation for the technical data,
operating conditions and operating limits of the axial piston unit.
5.2 Product description
The A4VG is a variable pump with an axial piston rotary group in swashplate design for
hydrostatic drives in closed circuits. The flow is proportional to the drive speed and
displacement. The flow can be smoothly changed using the control (cradle)(12). For
axial piston units with swashplate design, the pistons are arranged axially relative to
the drive shaft.
In the closed circuit, the hydraulic fluid flows from the hydraulic pump to the
consumer, e.g. hydraulic motor and from there directly back to the hydraulic pump.
There is a high-pressure side and a low-pressure side which alternate depending on
which side is under load.
5.2.1 Axial piston unit layout
1
2
3 4
5
6
7
891011
12
Fig. 2: Series 35 A4VG layout
1 Drive shaft
2 Retaining plate
3 Stroking piston
4 Control plate
(distributor plate)
5 High-pressure side
6 Boost pump
7 Low-pressure side
8 Suction port
9 Cylinder
10 Piston
11 Slipper pad
12 Cradle
Closed circuit