Bosch Rexroth A10VGT User manual

Instruction manual
RE 92770-01-B/11.2016
Replaces: –.–
English
Axial piston variable pump
A10VGT
Series 11

© Bosch Rexroth AG 2016. 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.

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1 About this documentation 5
1.1 Validity of the documentation 5
1.2 Required and supplementary documentation 5
1.3 Display of information 6
1.3.1 Safety instructions 6
1.3.2 Symbols 7
1.3.3 Designations 7
1.3.4 Abbreviations 7
2 Safety instructions 8
2.1 About this chapter 8
2.2 Intended use 8
2.3 Improper use 8
2.4 Personnel qualifications 9
2.5 General safety instructions 10
2.6 Product-specific safety instructions 11
2.7 Personal protective equipment 14
3 General instructions on damage to property and theproduct 15
4 Scope of delivery 18
5 About this product 19
5.1 Performance description 19
5.2 Product description 19
5.2.1 Layout of the axial piston unit 19
5.2.2 Functional description 20
5.3 Product identification 21
6 Transport and storage 22
6.1 Transporting the axial piston unit 22
6.1.1 Transporting by hand 22
6.1.2 Transporting with a lifting device 22
6.2 Storing the axial piston unit 24
7 Installation 26
7.1 Unpacking 26
7.2 Installation conditions 26
7.3 Installation position 28
7.3.1 Below-reservoir installation (standard) 28
7.3.2 Above-reservoir installation 29
7.4 Installing the axial piston unit 30
7.4.1 Preparation 30
7.4.2 Dimensions 30
7.4.3 General instructions 31
7.4.4 Installation with coupling 31
7.4.5 Installation on a gearbox 32
7.4.6 Installation with cardan shaft 33
7.4.7 Completing installation 33
7.4.8 Changing the lever position of the HW control 34
7.4.9 Hydraulically connecting the axial piston unit 35
7.4.10 Electrically connecting the axial piston unit 39
7.5 Performing flushing cycle 40
Contents

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8 Commissioning 41
8.1 Initial commissioning 41
8.1.1 Filling the axial piston unit 41
8.1.2 Testing the hydraulic fluid supply 43
8.1.3 Performing functional test 43
8.2 Running-in phase 44
8.3 Recommissioning after a standstill 44
9 Operation 45
9.1 Manual override of the electrical control 45
10 Maintenance and repair 46
10.1 Cleaning and care 46
10.2 Inspection 47
10.3 Maintenance 47
10.4 Repair 48
10.5 Spare parts 48
11 Removal and replacement 49
11.1 Required tools 49
11.2 Preparing for removal 49
11.3 Performing removal 49
11.4 Preparing the components for storage or further use 49
12 Disposal 50
13 Extension and conversion 51
14 Troubleshooting 52
14.1 How to proceed for troubleshooting 52
14.2 Malfunction table 53
15 Technical data 57
16 Alphabetical index 58
Contents

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1 About this documentation
1.1 Validity of the documentation
This documentation is valid for the following products:
•Axial piston variable pump A10VGT Series 11
This documentation is intended for machine/system manufacturers, assemblers and
service engineers.
This documentation contains important information on the safe and appropriate
transport, installation, commissioning, operation, maintenance, removal and simple
troubleshooting of the axial piston unit.
▶ Read this documentation completely and in particular the chapter2 “Safety
instructions” on page8 and chapter3 “General instructions on damage to
property and theproduct” on page15 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 of your Axial piston variable pump
A10VGT.
– Order confirmation
Installation drawing
Contains the outer dimensions, all connections and the hydraulic circuit
diagram for your Axial piston variable pump A10VGT.
Please request the
installation drawing
from your contact at
Bosch Rexroth.
Installation drawing
Axial piston variable pump A10VGT
Contains the permissible technical data.
92770 Data sheet
Mineral oil-based hydraulic fluids and related hydrocarbons
Describes the requirements on a mineral oil-based hydraulic fluid and related
hydrocarbons for operation with Rexroth hydraulic components, and assists you
in selecting a hydraulic fluid for your hydraulic 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 (HFDU/HFDR)
Describes the requirements on fire-resistant, water-free hydraulic fluids
(HFDU/HFDR) for operation with Rexroth hydraulic components and assists
you in selecting a hydraulic fluid for your hydraulic system.
90222 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

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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 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11 and in chapter3 “General instructions on damage
to property and theproduct” on page15 and before a sequence of actions or an
instruction for action involving a risk of personal injury or property damage. The
described danger prevention measures must be observed.
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 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.
NOTICE Property damage: The product or the environment may
get damaged.

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1.3.2 Symbols
The following symbols indicate information that is not safety-relevant but increases
understanding of the documentation.
Table 3: Meaning of the symbols
Symbol Meaning
If this information is disregarded, the product cannot be used and/or
operated to the optimum extent.
▶ Single, independent action
1.
2.
3.
Numbered instruction:
The numbers indicate that the actions must be completed one after the other.
1.3.3 Designations
This documentation uses the following designations:
Table 4: Designations
Designation Meaning
A10VGT Axial piston variable pump, closed circuit, for use in concrete mixer truck
Threaded plug Metal screw, pressure-resistant
Protective plug Made out of plastic, not pressure-resistant, only for transportation
As a generic term for “Axial piston variable pump A10VGT”, the designation “axial
piston unit” will be used hereinafter.
1.3.4 Abbreviations
This documentation 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)
EP Proportional control, electric
HW Proportional control, hydraulic, mechanical servo
ISO International Organization for Standardization
JIS Japan Industrial Standard
RE Rexroth document in the English language
VDI2230 Directive for the systematic calculation of high duty bolted joints and
joints with one cylindrical bolt 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 according to the generally accepted
rules of current technology. There is, however, still a danger of personal injury or
property damage if this chapter and the safety instructions in this documentation
are not complied with.
▶ Read this documentation completely and thoroughly before working with the
axial piston unit.
▶ Keep this documentation 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 in
the sense of the EC Machinery Directive 2006/42/EC. A component is exclusively
intended to form a partly complete machine or a complete machine 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 A10VGT is only approved as a pump for hydrostatic drum drives
of concrete mixer trucks in a closed circuit. The pump has been specifically designed
and constructed for the load collectives in this particular application.
The performance data given is based on this load collective.
▶ Observe the technical data, the application and operating conditions and
the performance limits as specified in data sheet92770 and in the order
confirmation. Information about approved hydraulic fluids can be found in
data sheet92770.
The axial piston unit is only intended for professional use and not for private use.
Intended use includes having read and understood the complete documentation,
especially chapter2 “Safety instructions” on page8.
2.3 Improper use
Any use other than that described as intended use shall be considered as improper
and is therefore impermissible.
Bosch Rexroth AG is not liable for damages resulting from improper use. The user
bears all risks from improper use.
The following foreseeable faulty usages are also be considered to be improper
(this list does not claim to be 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

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•Use of add-ons (e.g., control unit, valves) not in combination with the specified
Rexroth components
•Use of the axial piston unit 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.
•Use of the axial piston unit under a continuous pressure differential between case
to ambient pressure greater than 2bar, whereby the ambient pressure must always
be lower than the case pressure. Momentary (t<0.1s) pressure peaks of up to
10bar are allowed. Beyond this, the maximum case pressure specified on the data
sheet cannot 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/EU
•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 documentation require basic mechanical, electrical
and hydraulics expertise, as well as knowledge of the associated technical terms.
For transporting and handling the product, additional knowledge is necessary with
regard to working with lifting devices and their slings. 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 skilled personnel.
Skilled persons are those who can recognize possible dangers and take the
appropriate safety measures due to their professional training, knowledge, and
experience, as well as their understanding of the relevant regulations pertaining to
the work to be done. Skilled personnel must follow the rules relevant to their field
and have the necessary hydraulics expert knowledge.
Hydraulic expert knowledge includes:
•reading and fully understanding hydraulic circuit diagrams,
•especially fully understanding the relationships with regard to safety devices
•and 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.
•Persons who install, operate, remove or maintain Rexroth products may not be under
the influence of alcohol, drugs or medication that may affect their 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 injury to personnel or property damage. For this reason, only use
the product in safety-relevant applications if this use is expressly specified and
permitted in the product documentation, for example in explosion protection
applications or in safety-related parts of a control system (functional safety).
•You may 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 permissible maximum pressure.
Operating the unit above the permissible maximum pressure can cause
components to burst and hydraulic fluid to escape under high pressure.
▶ Changes to the factory settings must 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 work and health protection
and transportation.
System/machine under pressure!
Danger to life or risk of injury, serious injuries when working on machines/systems
not secured! Risk of property damage!
▶ Switch off the entire system and secure it against reconnection according
to parameters provided by the machine/system manufacturer.
▶ Make sure that all relevant components of the hydraulic system are depressurized.
Follow the parameters given by the machine/system manufacturer.
▶ 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 oil 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 set up the relevant part of the machine/system so that it is free of electrical
voltage before you install the product or when connecting and disconnecting
connectors. Protect the machine/system against being re-energized.
Danger from unforeseen machine movement!
Danger to life or risk of 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 additional protective measures are necessary for the application
on your machine in order to avoid unintentional actuation. If necessary, make
sure that these are properly implemented.
▶ Wear suitable protective clothing.
Restriction of the 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
respond correctly to 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
Restriction of the load holding function in lifting winches!
Risk of injury or property damage!
Moving parts in high-pressure relief valves may in certain circumstances become
stuck in an undefined position due to contamination (e.g. contaminated hydraulic
fluid). This can result in restriction or loss of the load holding function in lifting
winches.
▶ Check whether the application on your machine requires additional safety
measures, in order to keep the load in a safe position.
▶ If necessary, make sure that these are properly implemented.
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 when in the vicinity of the operating axial piston unit.
Hot surfaces on the 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 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 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, 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.
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 component and repair the leak.
▶ Never attempt to block or seal the leak or oil jet with a cloth.

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CAUTION
Danger from improper handling!
Risk of slipping! 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 and provisions in your country.
All pieces of personal protective equipment must be intact.

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3 General instructions on damage to
property and theproduct
The instructions below apply to chapters 6 to 14.
NOTICE
Danger from improper handling!
Product can get 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 attachment 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 electro-welding or 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 inadequate lubrication!
Product can get 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; if necessary,
recommission. With above-reservoir installation, the housing area may drain
via the drain line after longer periods of disuse (air enters via the shaft seal)
or via 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 get damaged!
▶ Before installation, remove all fluids from the axial piston unit to prevent mixing
with the hydraulic fluid used in the machine/system.
▶ Any mixing of hydraulic fluids from different manufacturers or different types
from the same manufacturer is generally not permitted.

16/60 General instructions on damage to property and theproduct
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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 axial piston unit must be installed in clean condition.
▶ Use only clean connections, hydraulic lines and assembled parts (e.g. measuring
devices).
▶ 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 plug-in connections 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 fluid during filling to minimize solid
particle contamination and water in the hydraulic system.
Improper cleaning!
Product can get damaged!
▶ Plug all openings with the appropriate protection equipment 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 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 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 collecting pan under the axial piston unit when filling and
draining the hydraulic fluid.
▶ Use an oil binding agent if hydraulic fluid is spilled.
▶ Observe the parameters in the safety data sheet for the hydraulic fluid and
the specifications provided by the system manufacturer.
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 axial piston unit, check the distances to nearby products
to ensure that they do not get damaged.
The warranty only applies to the delivered configuration.
The entitlement to warranty cover will be rendered void 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
Fig. 1: Axial piston unit
The following is included in the scope of delivery:
•Axial piston unit as per order confirmation
The following parts are also assembled prior to delivery:
•Protective covers(1)
•Protective plug/threaded plug(2)

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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 as a pump for hydrostatic drum drives of concrete mixer trucks in
a closed circuit. The pump has been specifically designed and constructed for the
load collectives in this particular application. The performance data given is based
on this load collective.
Refer to data sheet 92770 and the order confirmation for the technical data,
operating conditions and operating limits of the axial piston unit.
5.2 Product description
The A10VGT is an Axial piston variable pump with swashplate design for hydrostatic
drives in closed circuits. The flow is proportional to the drive speed and displacement.
The flow can be steplessly changed by controlling the cradle (11).
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 Layout of the axial piston unit
1
2
34
5
6
7
89101112
Fig. 2: Layout of the A10VGT Series 11
1 Drive shaft
2 Retaining plate
3 Stroking piston
4 Control unit
(here HW as example)
5 Suction port
6 Control plate
(distributor plate)
7 Boost pump
8 Cylinder
9 Piston
10 Slipper pad
11 Cradle
12 Coupling flange
(optional)
Closed circuit

20/60 About this product
Bosch Rexroth AG, A10VGT Series 11, RE 92770-01-B/11.2016
5.2.2 Functional description
Torque and rotational speed are applied to the drive shaft(1) by a drive motor.
The drive shaft is connected by splines to the cylinder(8) to set this in motion. With
every revolution, the pistons (9) execute a stroke in the cylinder bores, the size of
which depends on the pitch of the cradle (11). The slipper pads(10) are held on with
the pistons and guided along the glide surface of the cradle by the retaining plate(2).
The pitch of the swashplate during a rotation causes each piston to move over the
bottom and top dead centers and back to its initial position. Here, hydraulic fluid is
fed in and drained out through the two control slots in the control plate(5) according
to the stroke displacement. On the high-pressure side the hydraulic fluid is pushed
out of the cylinder chamber and into the hydraulic system by the pistons. At the same
time, hydraulic fluid flows into the growing piston chamber on the low-pressure side.
In a closed circuit, supported by the return and boost pressure.
The two high-pressure relief valves protect the hydrostatic transmission (pump and
motor) from overloading. They limit the maximum pressure in the respective
high-pressure line and serve simultaneously as boost valves. High-pressure relief
valves are not working valves and are only suitable for pressure peaks or high rates
of pressure change.
The boost pump (7) continuously supplies a sufficient volume of fluid (boost volume)
from a small reservoir to the low-pressure side of the closed circuit via a check valve
to replenish the internal leakage of the variable pump and consumer. The boost
pump is an internal gear pump which is driven directly via the drive shaft.
Actuation of the sequence valve establishes pressure equilibrium in the stroking
chambers. The spring in the stroking chamber moves the stroking piston towards
the central position (neutral position). The reset function is influenced by the
current working pressure and the rotational speed.
▶ Use an appropriate emergency-off device to ensure that the drive can be brought
to a safe position at any time. The machine or system manufacturer is responsible
for the installation of a proper emergency-off device.
The swivel angle of the cradle(11) is infinitely variable. Adjusting the swashplate
swivel angle controls the piston stroke and, therefore, the displacement. Adjusting
the swashplate through the neutral position will change the direction of flow
(making reversing operation possible). The swivel angle is controlled hydraulically
by means of the stroking piston. The cradle is mounted in swivel bearings for easy
motion and the neutral position is spring-centered. Increasing the swivel angle
increases the displacement; reducing the angle results in a corresponding reduction
in displacement.
Various control devices are available depending on requirements. Information
about this can be found in data sheet 92770.
Pump
High-pressure safeguarding
Boost pump
Sequence valve (optional)
Control