Mobile Hydraulics

Workbook
TP 800

With CD-ROM

C (X1)

D (X2)

LS
P
T

T
C

LS
LS1

LS2

Festo Didactic
574166 en

Order no.
Revision level:
Authors:
Editor:
Graphics:
Layout:

574166
03/2013
Ulrich Schedel, Levent Unan
Christine Lffler
Doris Schwarzenberger
03/2013, Susanne Durz, Christine Lffler

Festo Didactic GmbH & Co. KG, 73770 Denkendorf, 2013

Internet: www.festo-didactic.com
e-mail: did@de.festo.com

The purchaser shall receive a single right of use which is non-exclusive, non-time-limited and limited
geographically to use at the purchaser's site/location as follows.
The purchaser shall be entitled to use the work to train his/her staff at the purchaser's site/location and
shall also be entitled to use parts of the copyright material as the basis for the production of his/her own
training documentation for the training of his/her staff at the purchaser's site/location with
acknowledgement of source and to make copies for this purpose. In the case of schools/technical colleges
and training centres, the right of use shall also include use by school and college students and trainees at
the purchaser's site/location for teaching purposes.
The right of use shall in all cases exclude the right to publish the copyright material or to make this available
for use on intranet, Internet and LMS platforms and databases such as Moodle, which allow access by a
wide variety of users, including those outside of the purchaser's site/location.
Entitlement to other rights relating to reproductions, copies, adaptations, translations, microfilming and
transfer to and storage and processing in electronic systems, no matter whether in whole or in part, shall
require the prior consent of Festo Didactic GmbH & Co. KG.

Contents
Intended use ___________________________________________________________________________ VIII
Preface
______________________________________________________________________________ IX
Introduction _____________________________________________________________________________ XI
Work and safety instructions ______________________________________________________________ XII
Mobile hydraulics training package (TP 800) _________________________________________________ XIV
Learning objectives ______________________________________________________________________ XV
Allocation of learning objectives to exercises_________________________________________________ XVII
Equipment set __________________________________________________________________________ XX
Allocation of components to exercises ____________________________________________________ XXVII
Notes for the teacher/trainer______________________________________________________________ XXX
Structure of the exercises ________________________________________________________________ XXXI
Component designations _________________________________________________________________ XXXI
CD-ROM contents _______________________________________________________________________ XXXI

Exercises and solutions: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1:
Exercise 1-2:
Exercise 1-3:
Exercise 1-4:
Exercise 1-5:
Exercise 1-6:
Exercise 1-7:
Exercise 1-8:
Exercise 1-9:

Examining performance for a controller using constant displacement pump

and fixed pressure limitation ____________________________________________________3
Examining performance for a controller using constant displacement pump
and adjusted pressure limitation using open-centre load-sensing pressure balance _____ 13
Examining performance of speed control using a 6/3-way proportional valve ___________ 23
Examining energy efficiency of speed control in an open-centre load-sensing system ____ 31
Moving and holding a load with a 6/3-way proportional valve _______________________ 41
Moving and holding a load with a piloted non-return valve __________________________ 51
Moving and holding a load with a pressure-relief valve as counter pressure ____________ 59
Moving and holding a load with a counterbalancing valve___________________________ 69
Examining parallel, series and tandem configurations ______________________________ 79

Exercises and solutions: Mobile hydraulics, advanced level steering system (TP 802)
Exercise 2-1:
Exercise 2-2:
Exercise 2-3:
Exercise 2-4:
Exercise 2-5:

Examining the steering valve in a hydrostatic steering system _______________________ 91

Examining steering when external forces are exerted ______________________________ 99
Examining overload protection for steering _____________________________________ 107
Examining a steering system with priority function _______________________________ 115
Designing a steering system for centre-pivot steering _____________________________ 123

Festo Didactic GmbH & Co. KG 574166

III

Exercises and solutions: Mobile hydraulics, advanced level working hydraulics (TP 803)
Exercise 3-1: Examining a hydraulic system with load-sensing-controlled variable displacement pump
Exercise 3-2: Examining the load hold function _____________________________________________
Exercise 3-3: Remotely controlling proportional directionalcontrol valves using a hydraulic joystick __
Exercise 3-4: Setting a (volumetric) flow rate independent of load ______________________________
Exercise 3-5: Setting the volumetric flow rate using a load-sensing-controlled pump unit ___________
Exercise 3-6: Examining a load-sensing system with upstream pressure balance __________________
Exercise 3-7: Examining a load-sensing system with downstream pressure balance ________________

133
143
151
159
169
179
191

Exercises and worksheets: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1:
Exercise 1-2:
Exercise 1-3:
Exercise 1-4:
Exercise 1-5:
Exercise 1-6:
Exercise 1-7:
Exercise 1-8:
Exercise 1-9:

Examining performance for a controller using constant displacement pump

and fixed pressure limitation ____________________________________________________3
Examining performance for a controller using constant displacement pump
and adjusted pressure limitation using open-centre load-sensing pressure balance _____ 13
Examining performance of speed control using a 6/3-way proportional valve ___________ 23
Examining energy efficiency of speed control in an open-centre load-sensing system ____ 31
Moving and holding a load with a 6/3-way proportional valve _______________________ 41
Moving and holding a load with a piloted non-return valve __________________________ 51
Moving and holding a load with a pressure-relief valve as counter pressure ____________ 59
Moving and holding a load with a counterbalancing valve___________________________ 69
Examining parallel, series and tandem configurations ______________________________ 79

Exercises and worksheets: Mobile hydraulics, advanced level steering system (TP 802)
Exercise 2-1:
Exercise 2-2:
Exercise 2-3:
Exercise 2-4:
Exercise 2-5:

Examining the steering valve in a hydrostatic steering system _______________________ 91

Examining steering when external forces are exerted ______________________________ 99
Examining overload protection for steering _____________________________________ 107
Examining a steering system with priority function _______________________________ 115
Designing a steering system for centre-pivot steering _____________________________ 123

Exercises and worksheets: Mobile hydraulics, advanced level working hydraulics (TP 803)
Exercise 3-1: Examining a hydraulic system with load-sensing-controlled variable displacement pump
Exercise 3-2: Examining the load hold function _____________________________________________
Exercise 3-3: Remotely controlling proportional directional control valves using a hydraulic joystick __
Exercise 3-4: Setting a (volumetric) flow rate independent of load ______________________________
Exercise 3-5: Setting the volumetric flow rate using a load-sensing-controlled pump unit ___________
Exercise 3-6: Examining a load-sensing system with upstream pressure balance __________________
Exercise 3-7: Examining a load-sensing system with downstream pressure balance ________________

IV

133
143
151
159
169
179
191

Festo Didactic GmbH & Co. KG 574166

Basics of mobile hydraulics

1

Introduction _____________________________________________________________________ I-5

2
2.1
2.2
2.3

Fundamentals of hydraulics ________________________________________________________ I-7

Basic principles of pressure and flow control valves _____________________________________ I-7
Pressure drop ___________________________________________________________________ I-10
Heat generation due to the pressure drop ____________________________________________ I-13

3
3.1
3.2
3.2.1
3.2.2
3.3
3.4
3.5

Closed hydraulic circuit (hydrostatic system) _________________________________________

Setting up a closed hydraulic circuit _________________________________________________
Hydraulic pumps for closed hydraulic circuits _________________________________________
Mechanically resetting the hydraulic pump ___________________________________________
Hydraulically resetting the hydraulic pump ___________________________________________
Feed pumps_____________________________________________________________________
Flushing valves __________________________________________________________________
Shock valves ____________________________________________________________________

I-15
I-15
I-17
I-17
I-18
I-20
I-20
I-21

4
4.1
4.1.1
4.1.2
4.2
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.2.6

Load-sensing systems ____________________________________________________________

Attributes of load-sensing systems __________________________________________________
Open-centre load-sensing systems __________________________________________________
Closed centre load-sensing systems _________________________________________________
Energy efficiency of the hydraulic pressure supply _____________________________________
Loss of energy ___________________________________________________________________
Pressureless pump recirculation circuit ______________________________________________
Flow rate control in systems with constant displacement pump ___________________________
Flow rate control in systems with variable displacement pump ___________________________
Flow rate control in open-centre load-sensing systems __________________________________
Flow rate control in closed centre load-sensing systems _________________________________

I-23
I-23
I-23
I-25
I-30
I-30
I-32
I-34
I-36
I-38
I-40

5
5.1
5.2
5.3

Variable-displacement pumps _____________________________________________________

Types of variable displacement pumps _______________________________________________
Vane pump _____________________________________________________________________
Axial piston pump ________________________________________________________________

I-42
I-42
I-42
I-44

6
6.1
6.2

Two-pump system with shut-off valve _______________________________________________ I-46

Requirements of a pump system for mobile machines ___________________________________ I-46
Example of a two-pump system with shut-off valve _____________________________________ I-47

7
7.1
7.2
7.3
7.4

Flow dividers ___________________________________________________________________

Synchronicity of drives ____________________________________________________________
Flow divider (50/50 slide valve) _____________________________________________________
Rotation flow valve _______________________________________________________________
Rotation flow valve for pressure boosting_____________________________________________

Festo Didactic GmbH & Co. KG 574166

I-48
I-48
I-48
I-50
I-51

VI

8
8.1
8.2
8.3
8.4
8.4.1
8.4.2
8.5
8.5.1
8.5.2
8.5.3
8.6

Valve manifold for mobile hydraulics _______________________________________________

Setup of valve blocks _____________________________________________________________
Circuit symbol of proportional directional control valves in valve modules __________________
Setup of valve modules ___________________________________________________________
Valve slides of proportional directional constant valves _________________________________
Design of valve slides _____________________________________________________________
Influence of control notches on flow rate characteristics _________________________________
Input module of a valve manifold ___________________________________________________
Design of an input module _________________________________________________________
Input module in combination with an open-centre valve module __________________________
Input module in combination with a closed-centre valve module __________________________
Shock and anti-cavitation valve _____________________________________________________

I-49
I-53
I-55
I-56
I-57
I-57
I-58
I-59
I-59
I-60
I-61
I-62

9
9.1
9.2
9.3
9.4
9.5

Circuits with open-centre valves ____________________________________________________

Open-centre valves _______________________________________________________________
Design of an open-centre 6/3-way valve ______________________________________________
Parallel connection _______________________________________________________________
Tandem configuration ____________________________________________________________
Series connection ________________________________________________________________

I-64
I-64
I-66
I-69
I-70
I-71

10
10.1
10.2
10.3

Load-independent flow rate control with proportional valves ____________________________

Proportional flow control valve _____________________________________________________
Upstream pressure balance ________________________________________________________
Downstream pressure balance _____________________________________________________

I-72
I-72
I-74
I-78

11
11.1
11.2
11.3
11.4

Holding and safe lowering of load __________________________________________________

Application example ______________________________________________________________
Piloted non return valve ___________________________________________________________
Pressure-relief valve ______________________________________________________________
Counterbalancing valve ___________________________________________________________

I-82
I-82
I-83
I-84
I-85

12
12.1
13.2
13.3

Hydraulic pilot control ____________________________________________________________

Hydraulic pilot control with a joystick ________________________________________________
Hydraulic joystick (manually-operated pilot control) ____________________________________
Electronic joystick (electro-hydraulic pilot control) _____________________________________

I-88
I-88
I-88
I-90

13
13.1
13.2
13.3
13.4
13.5
13.6
13.7

Prioritising consuming devices _____________________________________________________

Necessity of prioritising consuming devices ___________________________________________
Pressure sequence valve __________________________________________________________
Circuit prioritisation ______________________________________________________________
Way valves with prioritisation ______________________________________________________
Static prioritity valve______________________________________________________________
Dynamic priority valve ____________________________________________________________
3-way flow control valve ___________________________________________________________

I-92
I-92
I-92
I-93
I-94
I-94
I-95
I-96

Festo Didactic GmbH & Co. KG 574166

14
14.1
14.2
14.2.1
14.2.2
14.3
14.3.1
14.3.2
14.3.3
14.3.4
14.4
14.4.1
14.4.2

Hydrostatic steering _____________________________________________________________ I-98

Design and characteristics of hydrostatic steering ______________________________________ I-98
Design of steering valves __________________________________________________________ I-98
Rotary slide valve and bush ________________________________________________________ I-99
Proportioning pump (Orbitrol pump) ________________________________________________ I-100
Versions of steering valves _______________________________________________________ I-101
Open-centre steering valves ______________________________________________________ I-101
Closed-centre steering valves _____________________________________________________ I-102
Load-sensing steering valves ______________________________________________________ I-103
Reaction and non-reaction steering valves ___________________________________________ I-103
Types of steering systems ________________________________________________________ I-104
Ackermann steering system with axle journal steering _________________________________ I-105
Articulated steering system _______________________________________________________ I-105

Picture credits ________________________________________________________________________ I-107

Festo Didactic GmbH & Co. KG 574166

VII

Intended use
The mobile hydraulics basic and advanced level training packages are only to be used:
for the intended purpose in teaching and training applications
when their safety functions are in flawless condition
The components in the training packages are designed in accordance with the latest technology as well as
recognised safety rules. However, life and limb of the user and third parties may be endangered, and the
components may be impaired, if they are used incorrectly.
The learning system from Festo Didactic has been developed and produced exclusively for training and
continuing vocational education in the field of automation technology. The training companies and/or
trainers must ensure that all trainees observe the safety instructions described in this workbook.
Festo Didactic hereby excludes all liability for damage suffered by the trainee, the training company and/or
any other third parties as a result of use of these equipment sets outside a purely training situation, unless
Festo Didactic has caused this damage wilfully or through gross negligence.

Festo Didactic GmbH & Co. KG 574166

VIII

Preface
Festo Didactics training system for automation and technology is geared towards various educational
backgrounds and vocational requirements. The learning system is therefore broken down as follows:
Technology oriented training packages
Mechatronics and factory automation
Process automation and control technology
Mobile robotics
Hybrid learning factories
The training system for automation and technology is continuously updated and expanded in accordance
with developments in the field of education, as well as actual professional practice.
The training packages deal with various technologies including pneumatics, electro-pneumatics,
servopneumatics, hydraulics, electro-hydraulics, proportional hydraulics, servohydraulics, mobile
hydraulics, programmable logic controllers, sensor technology, electrical engineering, electronics and
electric drives.

The modular design of the training system allows for applications which go above and beyond the
limitations of the individual training packages. For example, PLC actuation of pneumatic, hydraulic and
electric drives is possible.

Festo Didactic GmbH & Co. KG 574166

IX

All training packages feature the following elements:

Hardware
Media
Seminars
Hardware
The hardware in the training packages is comprised of industrial components and systems that are specially
designed for training purposes. The components contained in the training packages are specifically
designed and selected for the projects in the accompanying media.
Media
The media provided for the individual topics consist of a mixture of teachware and software. The teachware
includes:
Technical literature and textbooks (standard works for teaching basic knowledge)
Workbooks (practical exercises with supplementary instructions and sample solutions)
Lexicons, manuals and technical books
(which provide technical information on groups of topics for further exploration)
Transparencies and videos (for easy-to-follow, dynamic instruction)
Posters (for presenting information in a clear-cut way)
Within the software, the following programmes are available:
Digital training programmes (learning content specifically designed for virtual training)
Simulation software
Visualisation software
Software for acquiring measurement data
Project engineering and design engineering software
Programming software for programmable logic controllers
The teaching and learning media are available in several languages. They are intended for use in classroom
instruction, but are also suitable for self-study.
Seminars
A wide range of seminars covering the contents of the training packages round off the system for training
and vocational education.

Do you have suggestions or criticism regarding this manual?

If so, send us an e-mail at did@de.festo.com.
The authors and Festo Didactic look forward to your comments.

Festo Didactic GmbH & Co. KG 574166

Introduction
This workbook is part of the training system for automation technology from Festo Didactic GmbH & Co. KG.
The system provides a solid basis for practice oriented training and vocational education. The mobile
hydraulics workbook communicates the basics and fundamental knowledge on the hydraulic systems of
mobile work machines.
The contents of the workbook are project exercises on the basic level of working hydraulics (TP 801),
advanced level steering systems (TP 802) and advanced level working hydraulics (TP 803). The workbook
also contains a basic information section on mobile hydraulics.
The basic level working hydraulics (TP 801) is suitable for basic training in mobile hydraulics.
Using practice-related problem descriptions, the energy balances of different hydraulic systems (also while
loaded) will be examined and evaluated. Control systems with multiple consuming devices are set up in
parallel, tandem and series connections and examined in relation to priority, flow rate distribution, and
pressure dependency. Further course topics are the behaviour of consuming devices while under loads and
the options for safely holding and lowering a load. Basic knowledge of hydraulic device technology is a
prerequisite.
The advanced level steering system (TP 802) communicates the basics of hydrostatic steering systems with
suitable hydraulic controls. The controllers contain typical components of a steering system like steering
valve, shock and anti-cavitation valve, steering cylinder and, if required, a secondary consuming device.
In the project exercises for advanced level working hydraulics (TP 803), details of the working hydraulics are
expanded upon and hydraulic controls with load-sensing controlled variable displacement pump will be set
up and examined.
Technical prerequisites for setting up the controllers include:
A Learnline or Learntop-S workstation equipped with Festo Didactic slotted profile plates.
A hydraulic power unit with constant displacement pump (volumetric flow rate: 4 l/min) for TP 801 and
TP 802, a hydraulic power unit with constant displacement pump (volumetric flow rate: 4 l/min) and
load-sensing controlled variable displacement pump for TP 803.
A power pack with short-circuit protection (input: 230 V, 50 Hz, output: 24 V, max. 5 A).
Laboratory safety cables
The practical execution of the nine project exercises for TP 801 requires a TP 801 equipment set. One TP 801
and TP 802 equipment set is required for the practical execution of each of the five project exercises for
TP 802. An additional TP 803 equipment set is necessary for the practical execution of the seven project
exercises for TP 803.
The theoretical fundamentals for understanding these exercises can be found in the following textbooks:
Hydraulics, basic level
Electro-hydraulics, basic level
as well as in the appendix to this workbook.
Data sheets for the individual components are also available (cylinders, valves, sensors etc.).

Festo Didactic GmbH & Co. KG 574166

XI

Work and safety instructions

General
Trainees should only work with the circuits under the supervision of a trainer.
Electrical devices (e.g. power supply units, compressors and hydraulic power units) may only be
operated in laboratory rooms which are equipped with residual current devices (RCDs).
Observe specifications included in the technical data for the individual components, and in particular all
safety instructions!
Malfunctions which may impair safety must not be generated in the training environment, and must be
eliminated immediately.
Wear personal safety gear (safety glasses, safety shoes) when working on circuits.
Mechanical system
Only reach into the setup when it is at a complete standstill.
Mount all of the components securely onto the slotted profile plate.
Limit switches may not be actuated frontally.
Danger of injury during troubleshooting!
Use a tool to actuate the limit switches, for example a screwdriver.
Set all components up so that activation of switches and disconnectors is not made difficult.
Adhere to the instructions regarding positioning of the components.
Always set up cylinders together with the appropriate cover.
Electrical functions
Use extra-low voltage only (max. 24 V DC).
Establish or interrupt electrical connections only in the absence of voltage!
Use only connecting cables with safety plugs for electrical connections.
When disconnecting connector cables, only pull by the plug, never by the cable.
Hydraulics
Limit system pressure to 6 MPa (60 bar).
Maximum permissible pressure for all devices included in the training package is 12 MPa (120 bar).
In the case of double-acting cylinders, pressure could be increased relative to the surface area ratio due
to pressure boosting. With a surface area ratio of 1:1.7 and a system pressure of 6 MPa (60 bar), it may
amount to more than 10 MPa (100 bar).
Danger of injury due to oil temperatures of greater than 50 C!
Hydraulic fluid with an oil temperature of greater than 50 C may result in burns or scalding.

XII

Festo Didactic GmbH & Co. KG 574166

Danger of injury when switching on the hydraulic power unit!

Cylinders may extend and retract automatically.
Connecting tubing lines
Never connect or disconnect tubing lines when the hydraulic power unit is running, or while under
pressure!
Couplings must be connected in the unpressurised state.
Set the coupling socket vertically onto the coupling nipple!
The coupling socket and the coupling nipple must not be fitted askew.
After each disconnection, make sure that the couplings have closed themselves!
Hydraulic circuit assembly
The hydraulic power unit and the electrical power pack
must be switched off when assembling the circuit.
Before commissioning, make sure that all tank lines have been connected
and that all couplings have been securely fitted.
Make sure that tubing lines connected to the cylinder are rinsed with hydraulic fluid,
if the volume of oil accommodated by the cylinder is less than the volume which can
be contained by the tubing lines.
Commissioning
Cylinders may only be commissioned with their covers in place.
Switch on the electrical power pack first, and then the hydraulic power unit.
Dismantling hydraulic circuits
Assure that pressure has been relived before dismantling the circuit.
Switch off the hydraulic power unit first, and then the electrical power pack.
If connections are decoupled while under pressure, pressure is trapped in the device by the non-return
valve in the coupling. This pressure can be vented with the pressure relief unit.

Mounting technology
The mounting boards for the components are equipped with mounting variant A, B or C:
Variant A, snap-in system
Lightweight devices which cannot be subjected to loads (e.g. directional control valves and sensors).
Simply clip the components into the slots on the slotted profile plate. Release the components from the
slots by actuating the blue lever.
Variant B, rotary system
Components with medium load capacity (e.g. hydraulic cylinders). These components are clamped to
the slotted profile plate with T-head bolts. The blue knurled nut is used for clamping and loosening.
Make sure that the T-head bolts have been turned 90 after tightening.
Variant C, screw system
For devices with high load capacity and devices which are seldom removed from the slotted profile plate
(e.g. the hydraulic power unit). These devices are fastened with socket head screws and T-head nuts.
Required accessories
Two digital multimeters are required to evaluate exercises which make use of the flow sensor.
The output voltage of the flow sensor is measured with the multimeter.

Festo Didactic GmbH & Co. KG 574166

XIII

Mobile hydraulics training package (TP 800)

The TP 800 training package consists of a multitude of individual training materials. This package refers to
components and basic circuits of the hydraulic systems of working machines. Individual components from
training package TP 800 may also be included in other packages.
Important TP 800 components
Permanent workstation with Festo Didactic profile plate
Equipment sets or individual components (e.g. cylinders, valves and pressure gauges)
Complete set of laboratory equipment
Media
The teachware for the training package TP 800 consists of one workbook. The contents of the workbook are
the project exercises on the basic level of working hydraulics (TP 801), advanced level steering systems
(TP 802) and advanced level working hydraulics (TP 803). The theoretical fundamentals for understanding
the exercises are described in the textbook attachment.
The workbook includes the exercise sheets and worksheets for the project exercise, the solutions to each
individual worksheet and a CD-ROM. A set of ready-to-use exercise sheets and worksheets is included in
each workbook for all of the exercises.
Data sheets for the hardware components are made available along with the equipment set.
Media
Textbooks

Hydraulics, basic level

Electro-hydraulics, basic level

Workbooks

Mobile hydraulics (TP 800)

Set of posters

Hydraulics

Simulation programme

FluidSIM Hydraulic

TP 810

Diagnostic system FluidLab M

Digital training programme

Web-based training, hydraulics Basics of hydraulics principles

Web-based training electro-hydraulices Basics of electro-hydraulics principles

Overview of media for training package TP 800

The media are offered in several languages. Further training materials can be found in our catalogues and on
the Internet.

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Festo Didactic GmbH & Co. KG 574166

Learning objectives

Mobile hydraulics: Basic level working hydraulics (TP 801)

To know the relationship between pressure, flow rate and power output.
To be able to calculate the power consumption of a hydraulic system.
To know that flow division can lead to energy losses in a hydraulic system.
To know that when using a constant displacement pump, non-decreasing volume flow leads to energy
loss.
To know how a constant displacement pump with an open-centre load-sensing pressure balance works.
To know the power-relevant advantages of a constant displacement pump with pressure regulation by
an open-centre load-sensing pressure balance over a constant displacement pump without an opencentre load-sensing pressure balance.
To be familiar with the mode of operation of a 6/3-way proportional valve.
To know that proportional directional control valves restrict inflow and outflow.
To know that a 6/3-way proportional valve with mid-position tank recirculation only generates minor
energy loss in mid-position.
To know how a shuttle valve works and how to use it.
To understand the control circuit of an open-centre load-sensing system.
To know that a proportional directional control valve in connection with an open-centre load-sensing
pressure balance represents a flow control valve.
To be able to use the cylinder load simulator (loading unit).
To understand the behaviour of the cylinders under load.
To know how to use a delockable double non-return valve for the purpose of secure holding.
To know the advantages and disadvantages of a delockable double non-return valve.
To be able to use a pressure-relief valve as a counter-pressure valve for secure holding and lowering.
To know the advantages and disadvantages of counter-pressure valves.
To be able to use a counterbalancing valve for the secure holding and lowering of a load.
To know the main difference between a counterbalancing valve and a pressure-relief valve.
To know that using a counterbalancing valve can reduce energy when lowering a load.
To know how series, parallel and tandem configurations of 6/3-way proportional valves work.
To be able to describe the advantages and disadvantages of these configuration types for an
application.

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XVI

Mobile hydraulics: Advanced level steering system (TP 802)

To understand how the steering valve works.
To know the properties of a non-reaction steering valve.
To understand the behaviour of the steering system under the influence of external forces.
To explain how a shock valve works.
To know for which applications shock valves are to be used.
To understand why it is necessary that one drive in a hydraulic system with multiple drives must
preferably be supplied by oil (priority function).
To know the effects of the priority function.
To know the setup of a centre-pivot steering.

Mobile hydraulics: Advanced level working hydraulics (TP 803)

To be able to explain the load-sensing function of valve manifolds.
To understand how the load-dependent pump pressure regulation (load-sensing) works.
To know the power-relevant advantages of hydraulic systems with load-sensing-controlled variable
displacement pumps.
To know how valve manifolds in mobile hydraulics work and how to use them.
To know the properties of a hydraulic joystick.
To be able to control proportional directional control valves with a hydraulic joystick.
To know the relationship between load changes and speed changes when using a flow control valve.
To know the properties of a 2-way flow control valve.
To know how to maintain a constant speed despite changing loads.
To be able to regulate flow rate with a load-sensing controlled pump unit.
To know the limits of a load-sensing system.
To understand the advantages and disadvantages of the upstream pressure balance in load-sensing
systems.
To be familiar with the mode of operation of the downstream pressure balance.
To know the advantages and disadvantages of the downstream pressure balance in load-sensing
systems.

Festo Didactic GmbH & Co. KG 574166

Allocation of learning objectives to exercises

Mobile hydraulics: Basic level working hydraulics (TP 801)
Exercise

1-1

1-2

1-3

1-4

1-5

1-6

1-7

1-8

1-9

Learning objective
To know the relationship between pressure, flow rate and power
output.

To be able to calculate the power consumption of a hydraulic

system.

To know that flow division can lead to energy losses in a hydraulic

system.

To know that when using a constant displacement pump, nondecreasing volume flow leads to energy loss.
To know how a constant displacement pump with an open-centre
load-sensing pressure balance works.

To know the power-relevant advantages of a constant

displacement pump with pressure regulation by an open-centre
load-sensing pressure balance over a constant displacement
pump without an open-centre load-sensing pressure balance.
To be familiar with the mode of operation of a 6/3-way
proportional valve.

To know that proportional directional control valves restrict inflow

and outflow.

To know that a 6/3-way proportional valve with mid-position tank

recirculation only generates minor energy loss in mid-position.

To know how a shuttle valve works and how to use it.

To understand the control circuit of an open-centre load-sensing

system.

To know that a proportional directional control valve in

connection with an open-centre load-sensing pressure balance
represents a flow control valve.

To be able to use the cylinder load simulator (loading unit).

To understand the behaviour of the cylinders under load.

To know how to use a delockable double non-return valve for the

purpose of secure holding.
To know the advantages and disadvantages of a delockable
double non-return valve.

Festo Didactic GmbH & Co. KG 574166

XVII

Exercise

1-1

1-2

1-3

1-4

1-5

1-6

1-7

1-8

1-9

Learning objective
To be able to use a pressure-relief valve as a counter-pressure
valve for secure holding and lowering.

To know the advantages and disadvantages of counter-pressure

valves.

To be able to use a counterbalancing valve for the secure holding

and lowering of a load.

To know the main difference between a counterbalancing valve
and a pressure-relief valve.

To know that using a counterbalancing valve can reduce energy

when lowering a load.

To know how series, parallel and tandem configurations of 6/3-

way proportional valves work.

To be able to describe the advantages and disadvantages of these
configuration types for an application.

Mobile hydraulics: Advanced level steering system (TP 802)

Exercise

2-1

2-2

2-3

2-4

2-5

Learning objective
To understand how the steering valve works.
To know the properties of a non-reaction steering valve.
To understand the behaviour of the steering system under the influence of external
forces.

To explain how a shock valve works.

To know for which applications shock valves are to be used.

To understand why it is necessary that one drive in a hydraulic system with multiple
drives must preferably be supplied by oil (priority function).
To know the effects of the priority function.
To know the setup of a centre-pivot steering.

XVIII

Festo Didactic GmbH & Co. KG 574166

Mobile hydraulics: Advanced level working hydraulics (TP 803)

Exercise

3-1

3-2

3-3

3-4

3-5

3-6

3-7

Learning objective
To be able to explain the load-sensing function of valve manifolds.

To understand how the load-dependent pump pressure regulation (loadsensing) works.

To know the power-relevant advantages of hydraulic systems with loadsensing-controlled variable displacement pumps.
To know how valve manifolds in mobile hydraulics work and how to use
them.
To know the properties of a hydraulic joystick.
To be able to control proportional directional control valves with a
hydraulic joystick.

To know the relationship between load changes and speed changes when
using a flow control valve.

To know the properties of a 2-way flow control valve.

To know how to maintain a constant speed despite changing loads.

To be able to regulate flow rate with a load-sensing controlled pump unit.

To know the limits of a load-sensing system.

To understand the advantages and disadvantages of the upstream

pressure balance in load-sensing systems.

To be familiar with the mode of operation of the downstream pressure

balance.

To know the advantages and disadvantages of the downstream pressure

balance in load-sensing systems.

Festo Didactic GmbH & Co. KG 574166

XIX

Equipment set
The equipment sets TP 801, TP 802 and TP 803 are compiled for the basic and advanced level mobile
hydraulics. Equipment set TP 801 includes all of the components which are necessary for mastering the
learning objectives for TP 801. To master the learning objectives for TP 802, you will require the components
of the three equipment sets TP 801 and TP 802. For the setup of the control units for TP 803, you will require
the components of the three equipment sets TP 801, TP 802 and TP 803. The equipment sets can be
supplemented with other equipment sets as desired.

Equipment set: Mobile hydraulics, basic level working hydraulics (TP 801), order no. 574161

XX

Designation

Order number

Quantity

6/3-way proportional hand lever valve, mid-position with tank recirculation

572141

3-way pressure regulator

544337

Shut-off valve

152844

Double non-return valve, delockable

572151

Flow control valve

152842

Pressure-relief valve

544335

Pressure balance for open-centre load-sensing

572123

Electronic pressure switch

548612

Flow sensor

567191

Hydraulic motor

152858

Diaphragm accumulator with shut-off block

152859

Non-return valve, opening pressure: 0.6 MPa

548618

Delockable counter balance valve (overcentre valve)

572149

T-distributor

152847

4-way manifold plate with pressure gauge

159395

Shuttle valve

572122

Cylinder load simulator (loading unit)

572145

Festo Didactic GmbH & Co. KG 574166

Graphic symbols, equipment set

Component

Graphic symbol

6/3-way proportional hand lever valve,

mid-position with tank recirculation

T1 B

P2

P1 T2

3-way pressure regulator

P T

Shut-off valve

Double non-return valve,

delockable

A2

B2

A1

B1

Flow control valve

Pressure-relief valve

Pressure balance for open-centre

load-sensing

P
0.55 MPa

Festo Didactic GmbH & Co. KG 574166

0.55 MPa
T

XXI

Component
Electronic pressure switch

Graphic symbol
ISO 1219-1

EN 60617-7

RD (1)
BK1 (4), SP1
BK2 (5), SP2
WH (2)
BU (3)

Flow sensor

ISO 1219-1

EN 60617-7

24V (RD)
q

0 10V
(BK)
0V (BU)

Hydraulic motor

Diaphragm accumulator with shutoff block

Non-return valve, opening pressure:

0.6 MPa

Delockable counter balance valve

(overcentre valve)

X (1:3)

T
T-distributor

XXII

Festo Didactic GmbH & Co. KG 574166

Component

Graphic symbol

4-way manifold plate,

with pressure gauge

Shuttle valve

B
A1

A2

Cylinder load simulator

(loading unit)

A1.1

A1.2

A2.1

A2.2

Equipment set: Mobile hydraulics, advanced level steering system (TP 802), order no. 574162
Designation

Order number

Quantity

4/3-way hand lever valve, working lines relieved in mid-position, detenting

544344

Steering valve (Orbitrol)

572146

Shock and replenishing manifold

572148

4-way return header, unpressurised

573026

Tubing line for unpressurised return

573024

Festo Didactic GmbH & Co. KG 574166

XXIII

Graphic symbols, equipment set

Component

Graphic symbol

4/3-way hand lever valve, working lines

relieved in mid-position, detenting

Steering valve (Orbitrol)

Shock and replenishing manifold

B2

A2

A1

B1

4-way return header, unpressurised

Tubing line for unpressurised return

XXIV

Festo Didactic GmbH & Co. KG 574166

Equipment set: Mobile hydraulics, advanced level working hydraulics (TP 803), order no. 5741632
Designation

Order number

Quantity

Flow control valve

152842

Pressure balance, downstream

572741

Pressure balance, upstream

573023

Load-sensing control block

572144

Tubing line for unpressurised return

573024

T-distributor

152847

Pilot controller (joystick), 2x2-channel

572147

Graphic symbols, equipment set

Component

Graphic symbol

Flow control valve

Pressure balance, downstream

A
35 kPa

35 kPa
P

Pressure balance, upstream

A
0.55 MPa

0.55 MPa
P

Load-sensing control block

D (X1.2) A1 B1

D (X2.2) A2 B2

LS
P
T

Festo Didactic GmbH & Co. KG 574166

XXV

Component

Graphic symbol

Tubing line for unpressurised return

T-distributor

Pilot controller (joystick),

X1.1

2x2-channel

X1.2

X2.1

X2.2

P
T

XXVI

Festo Didactic GmbH & Co. KG 574166

Allocation of components to exercises

Equipment set: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise

1-1

1-2

1-3

1-4

1-5

1-6

1-7

1-8

1-9

Component
6/3-way proportional hand lever valve, mid-position with tank
recirculation
3-way pressure regulator
Shut-off valve

Double non-return valve, delockable

Flow control valve

Pressure-relief valve

Pressure gauge
Pressure balance for open-centre load-sensing

1
2

Electronic pressure switch

Flow sensor

Hydraulic motor

Diaphragm accumulator with shutoff block

Non-return valve, opening pressure: 0.6 MPa

Delockable counter balance valve (overcentre valve)

T-distributor

4-way manifold plate with pressure gauge

Shuttle valve

1-6

1-7

1-8

1-9

Cylinder load simulator (loading unit)

Required accessories
Exercise

1-1

1-2

1-3

1-4

1-5

Power pack, 24 V DC

Tubing line

10

13

15

12

15

16

16

16

Component
Digital multimeter
Hydraulic power unit with constant displacement pump
(volumetric flow rate: 4 l/min)

Festo Didactic GmbH & Co. KG 574166

XXVII

Mobile hydraulics equipment set: Advanced level steering system (TP 802)
Exercise

2-1

2-2

2-3

2-4

2-5

Component
4/3-way hand lever valve, working lines relieved in mid-position, detenting
Steering valve (Orbitrol)

Shock and replenishing manifold

4-way return header, unpressurised

Tubing line for unpressurised return

3-way pressure regulator

Shut-off valve

Pressure gauge
Electronic pressure switch

Flow sensor

Hydraulic motor

Diaphragm accumulator with shutoff block

Non-return valve, opening pressure: 0.6 MPa

Delockable counter balance valve (overcentre valve)

T-distributor

4-way manifold plate with pressure gauge

Cylinder load simulator (loading unit)

2-1

2-2

2-3

2-4

2-5

* Components with grey background come from equipment set TP 801.

Required accessories
Exercise
Component
Digital multimeter

XXVIII

Hydraulic power unit with constant displacement pump

(volumetric flow rate: 4 l/min)

Power pack, 24 V DC

Tubing line

13

16

15

Festo Didactic GmbH & Co. KG 574166

Mobile hydraulics equipment set: Advanced level working hydraulics (TP 803)
Exercise

3-1

3-2

3-3

3-4

3-5

3-6

3-7

Component
Flow control valve
Pressure balance, downstream

Pressure balance, upstream

Load-sensing control block

Tubing line for unpressurised return

T-distributor

Pilot controller (joystick), 2x2-channel

4-way return header, unpressurised

Tubing line for unpressurised return

Shut-off valve

Flow control valve

Pressure-relief valve

Pressure gauge
Electronic pressure switch

Flow sensor

Hydraulic motor

T-distributor
4-way manifold plate with pressure gauge

Shuttle valve
Cylinder load simulator (loading unit)

*) Components with light grey background are components from the equipment set TP 802
**) Components with dark grey background are components from the equipment set TP 801

Required accessories
Exercise

3-1

3-2

3-3

3-4

3-5

3-6

3-7

Component
Digital multimeter
Hydraulic power unit with a constant displacement pump (volumetric flow
rate: 4 l/min) and load-sensing-controlled variable displacement pump

Power pack, 24 V DC

Tubing line

10

10

15

16

Festo Didactic GmbH & Co. KG 574166

XXIX

Notes for the teacher/trainer

Learning objectives
The basic learning objective of this workbook is to understand, set up, safely commission and analyse using
measurement technology the basic hydraulic circuits of mobile work machines. This knowledge is gained by
means of theoretical questions and by actually setting up the circuits on the slotted profile plate. Direct
interplay of theory and practice ensures fast progress and long-lasting learning. The more specific learning
objectives are documented in the matrix. Concrete, individual learning objectives are assigned to each
exercise.
Required time
The time required for working through the exercises depends on the learners previous knowledge of the
subject matter. Each exercise should take approximately 1 to 1 hours.
Components of the equipment sets
The project exercises of the workbook and associated equipment sets TP 801, TP 802 and TP 803 are
coordinated with each other. For the nine exercises of basic level working hydraulics (TP 801), you will
require the components of a TP 801 equipment set. For the five exercises of the advanced level steering
system (TP 802), you will require the components of each of the TP 801 and TP 802 equipment sets. For the
seven exercises of advanced level working hydraulics (TP 803), you will require the components of the three
equipment sets TP 801, TP 802 and TP 803.
Standards
The following standards are applied in this workbook:
DIN ISO 1219-1
Fluid power systems and components Graphic symbols and
circuit diagrams
EN 60617-2 to EN 60617-8
Graphic symbols for diagrams
EN 81346-2
Industrial systems, installations and equipment and industrial products;
structuring principles and reference designations
Identification in the workbook
Solutions and supplements in graphics or diagrams appear in red.
Components used to simulate the load for the application have grey backgrounds in the circuit diagram.
Classifications in the set of exercises
Texts which require completion are identified with a grid or grey table cells.
Graphics and diagrams which require completion include a grid.
Notes for the lesson
Additional information is provided here regarding the didactic-methodological procedure, the individual
components and the completed controllers. These notes are not included in the set of exercises.

XXX

Festo Didactic GmbH & Co. KG 574166

Solutions
The solutions specified in this workbook result from test measurements. The results of your measurements
may deviate from these.

Structure of the exercises

All of the project exercises of the basic level TP 801 and the two advanced levels TP 802 and TP 803 have the
same methodical structure. The tasks and are broken down into:
Title
Learning objectives
Problem description
Positional sketch
Project assignments
Work aids
Worksheets
The workbook includes the solutions for all of the worksheets for all exercises.

Component designations
Components are designated in circuit diagrams in accordance with DIN ISO 1219-2. All of the components
included in any given circuit have the same primary identifying number. Letters are assigned depending on
each respective type of component. Consecutive numbers are assigned if several components of the same
type are included within a single circuit.
Cylinders:
Valves:
Sensors:
Signal input:
Accessories:

1A1, 2A1, 2A2 ...

1V1, 1V2, 1V3, 2V1, 2V2, 3V1
1B1, 1B2 ...
S1, S2
0Z1, 0Z2, 1Z1

CD-ROM contents
The workbook is included on the CD-ROM as a PDF file. The CD-ROM also provides you with additional
media.
The CD-ROM contains the following folders:
Operating instructions
Illustrations
Data sheets

Festo Didactic GmbH & Co. KG 574166

XXXI

Operating instructions
Operating instructions are provided for various components included in the training package. These
instructions are helpful when using and commissioning the components.
Illustrations
Photos and graphics of components and industrial applications are made available. These can be used to
illustrate individual tasks or to supplement project presentations.
Data sheets
The data sheets for the components included in the training package are supplied along with the equipment
set, and are additionally available as PDF files.

XXXII

Festo Didactic GmbH & Co. KG 574166

Contents
Exercises and solutions: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1: Examining performance for a controller using constant displacement pump
and fixed pressure limitation ____________________________________________________3
Exercise 1-2: Examining performance for a controller using constant displacement pump
and adjusted pressure limitation using open-centre load-sensing pressure balance ______ 13
Exercise 1-3: Examining performance of speed control using a 6/3-way proportional valve ___________ 23
Exercise 1-4: Examining energy efficiency of speed control in an open-centre load-sensing system _____ 31
Exercise 1-5: Moving and holding a load with a 6/3-way proportional valve________________________ 41
Exercise 1-6: Moving and holding a load with a piloted non-return valve __________________________ 51
Exercise 1-7: Moving and holding a load with a pressure-relief valve as counter pressure ____________ 59
Exercise 1-8: Moving and holding a load with a counterbalancing valve ___________________________ 69
Exercise 1-9: Examining parallel, series and tandem configurations ______________________________ 79

Festo Didactic GmbH & Co. KG 574166

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1
Examining performance for a controller using constant displacement pump
and fixed pressure limitation
Learning objectives
After completing this exercise:
you will be familiar with the relationship between pressure, flow rate and power output.
you will be able to calculate the power consumption of a hydraulic system.
you will know that flow division can lead to energy losses in a hydraulic system.
you will know that when using a constant displacement pump, non-decreasing volume flow leads to
energy loss.

Problem description
The motor speed of a wheel milling cutter is controlled using a flow control valve. The rotation of the motor
is only in one direction. The load acting on the motor changes depending on the soil conditions.
Examine how different load requirements affect the energy balance of the controls.

Positional sketch

Wheel saw, Bobcat, www.bobcat.eu

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

1.
2.
3.
4.
5.
6.

Parameters
When the hydraulic power unit is switched on, the motor will turn.
The load on the motor should be simulated using a proportional pressure-relief valve.

Project assignments
Set up the controller.
Familiarise yourself with the commissioning procedure.
Find out about the procedure when taking measurements in the electrical circuit.
Double check the controller configuration.
Measure the pressure and flow rate at different load pressures.
Calculate the power output of the pump unit; the effective power and the power loss based on the
measured values. Depict the calculated power output in the bar chart and evaluate the results.

Visual inspection
Continuous visual inspection for defects in tubing and hydraulic devices is an essential part of
hydraulic safety standards.

Work aids
Data sheets, operating instructions
Hydraulics textbook
Basics of mobile hydraulics (see attachment)

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

1. Setting up the controller

1B4

p2
P

1V4
1V3

1B3

p1

1B1

1V1
n

LS

P1

P2

q2

T
T

1B2

1A1

1V2

45 bar

q1

0Z1

LA

LA

60 bar

Circuit diagram

Note for the lesson

The shut-off valve is used for switching pump recirculation. This type of commissioning circuit is
used for all of the exercises below as well.
Electronic pressure switches are used to display precise pressure values.
If the hydraulic motor is only used in connection with a flow sensor, the combination of the two will
be given the equipment designation B for a sensor. If the hydraulic motor is an independent driving
component of the control system, it will be given its own designation A (also only in connection with
a flow sensor).

Note
The pressure-relief valve 1V4 is used to set load pressures.

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

Quantity

Labelling

Designation

1B3, 1B4

Electronic pressure switch

1B1, 1B2

Flow sensor, coupled with hydraulic motor

1A1

Hydraulic motor

1V3

Flow control valve

1V1, 1V4

Pressure-relief valve

1V2

Shut-off valve

4-way manifold plate with pressure gauge

Tubing line

0Z1

Hydraulic power unit with constant displacement pump

Equipment list

Note
You will need the following in order to perform the measurements.
1 power pack 24 V DC
2 digital multimeters

Set up the controller.

Observe the following points when setting up the controller:

Set the pressure-relief valve for the constant displacement pump of the hydraulic power unit to a
pressure of 60 bar (6 MPa) before setting up the control.
Use the circuit diagram.
Designate the components.
Connecting tubing lines
Never connect or disconnect tubing lines when the hydraulic power unit is running, or while under
pressure!
Couplings must be connected in the unpressurised state.
Set the coupling socket vertically onto the coupling nipple!
The coupling socket and the coupling nipple must not be fitted askew.
Selecting and laying tubing lines
Select the tubing line length such that adequate leeway is available
in order to accommodate changes in length which result from pressure.
Avoid mechanical stressing of the tubing line.
Do not bend the tubing line into a radius of less than its specified minimum bending radius
of 51 mm.
Do not twist the tubing line during installation.
Make sure that tubing lines do not become kinked.
Mark the completed tubing connections in the hydraulic circuit diagram.

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

2. Becoming familiar with the commissioning procedure

Information
During practice operation and for industrial maintenance purposes, safe commissioning is
undertaken at low pressure which is then increased up to the maximum value. This is possible with
either a pressure-relief valve or a pump recirculation circuit. At low pressure, leaks can be safely
detected after device replacement, for example.
Commissioning procedure with pump recirculation circuit
1. Switch to pump recirculation by opening the shut-off valve.
2. With electro-hydraulic controls, activate the electrical 24 V DC control voltage.
3. Switch the hydraulic pump on.
4. Slowly close the shut-off valve until a circulating pressure of approximately 15 bar prevails.
Immediately set the pump back to recirculation in the event of leaks.
5. Run the sequence once and watch for leaks.
6. Fully close the shut-off valve and set the pressure limit at the pressure-relief valve of the
hydraulic power unit to the specified value.

3. Finding out about the procedure when taking measurements in the electrical circuit

Safety instructions

Before measuring, make sure that the section of the controller in which you intend to take
measurements only works with an electrical voltage of no greater than 24 V DC!
Measurements within sections of the controller which function with higher voltages (e.g. 230 V)
may only be performed by persons who have received appropriate training or instruction.
Incorrect performance of this measurement is life endangering!
Observe the safety precautions for working with electrical power!

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

Information
Procedure for performing measurements in the electrical circuit
1.
2.
3.

Switch off supply power to the electrical circuit.

Select the desired operating mode at the multimeter (e.g. direct current measurement).
Connect the measuring instrument with correct polarity when measuring direct current/
direct voltage.
4. Select the largest measuring range.
5. Switch supply power to the electrical circuit back on.
6. Watch the display and switch to increasingly smaller measuring ranges step-by-step.
7. Read the value from the display after arriving at the smallest possible measuring range.

4. Double checking the controller setup

Observe the following points when commissioning the controller:
Before commissioning, make sure that all tank lines have been connected and that all couplings have
been securely fitted.
Fully close the flow control valve 1V3.
Fully open both pressure-relief valves 1V1 and 1V4.
Switch to pump recirculation by opening shut-off valve 1V2.
Switch off the 24 V DC electrical supply voltage for the flow sensors and pressure switches.
Note
You will find information on the sensors in the operating instructions.
When using the analogue output of the pressure switch, make sure it is set to between 0-10 V.

Switch the hydraulic power unit on.

Slowly close the shut-off valve 1V2. The entire pump unit delivery rate flows at low pressure through the
pressure-relief valve 1V1 to the tank.
Immediately set the pump back to recirculation in the event of leaks.
Set the pressure at the pressure-relief valve 1V1 to 45 bar.
Perform the measurement tasks.

5. Measuring pressure and flow rate at different load pressures

Execution
Set the pressure-relief valve 1V1 to 45 bar. Set the values indicated in the table for the flow control
valve 1V3 and the pressure-relief valve 1V4. Measure the pressure and flow rate for these values.

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

Set the values indicated in the table. Enter the measured pressure and flow rate values into the table.

Load case

Valve specifications

Pump pressure
p1 [bar]

Flow rate
q1 [l/min]

Load pressure
p2 [bar]

Flow rate
q2 [l/min]

1V3: open
1V4: Minimum pressure

15.8

4.14

12.4

4.22

1V3: open

33

4.1

30

4.18

1V4: Minimum pressure

43.8

4.06

3.2

0.5

43.6

4.06

30

0.5

40.6

4.06

25

45

4.06

Measurement log

Notes
Fully open the flow control valve 1V3 before dismantling the controller.
Fully open the pressure-relief valves 1V1 and 1V4 before dismantling.

6. Calculating the pumping power, effective power and power loss

Information
The formula for calculating the power in the hydraulic system when using the indicated physical
units is:

q p
600

P
q
p

Power [kW]
Flow rate [l/min]
Pressure [bar]

Power output of the pump unit: PP

q p
PP 1 1
600
PP Power output of the pump unit [kW]:
q1 Flow volume of the pump unit [l/min]
p1 Pump pressure [bar]

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

Effective power (output of the consuming device): PL

q p
PL 2 2
600
PL Output of the consuming device [kW]
q2 Flow rate to the consuming device [l/min]
p2 Load pressure [bar]
Power loss: PV
PV PP PL
PV Power loss [kW]

a) Calculate the pumping power, effective power and power loss for the load cases a to f (see workbook 4).
Enter the values to the table.
Load case

Pumping power
PP [kW]

Effective power
PL [kW]

Power loss
PV [kW]

0.109

0.087

0.022

0.226

0.209

0.017

0.296

0.003

0.293

0.295

0.025

0.27

0.275

0.083

0.192

0.305

0.305

Performance for the load cases a to f

10

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

b) Transfer the performance values for load cases a to f to a bar chart.

0.35
kW
0.25
0.2
0.15
0.1
PP
0.05
0

PL
PV
PP PL PV
a

PP PL PV
b

PP PL PV
c

PP PL PV
d

PP PL PV
e

PP PL PV
f

PP Pumping power
PL Effective power
PV Power loss
Performance of the system with constant displacement pump and pressure limitation with different load cases a to f

c)

When is power loss PV particularly high? Give reasons for your answer.
Power loss (PV) is particularly high when the flow rate of the consuming device (q2) is low. In this case,
almost the entire delivery rate of the pump unit must discharge at maximum pressure through the
pressure-relief valve.

Festo Didactic GmbH & Co. KG 574166

11

Contents
Exercises and worksheets: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1:
Exercise 1-2:
Exercise 1-3:
Exercise 1-4:
Exercise 1-5:
Exercise 1-6:
Exercise 1-7:
Exercise 1-8:
Exercise 1-9:

Examining performance for a controller using constant displacement pump

and fixed pressure limitation ____________________________________________________3
Examining performance for a controller using constant displacement pump
and adjusted pressure limitation using open-centre load-sensing pressure balance _____ 13
Examining performance of speed control using a 6/3-way proportional valve ___________ 23
Examining energy efficiency of speed control in an open-centre load-sensing system ____ 31
Moving and holding a load with a 6/3-way proportional valve _______________________ 41
Moving and holding a load with a piloted non-return valve __________________________ 51
Moving and holding a load with a pressure-relief valve as counter pressure ____________ 59
Moving and holding a load with a counterbalancing valve___________________________ 69
Examining parallel, series and tandem configurations ______________________________ 79

Exercises and worksheets: Mobile hydraulics, advanced level steering system (TP 802)
Exercise 2-1:
Exercise 2-2:
Exercise 2-3:
Exercise 2-4:
Exercise 2-5:

Examining the steering valve in a hydrostatic steering system _______________________ 91

Examining steering when external forces are exerted ______________________________ 99
Examining overload protection for steering _____________________________________ 107
Examining a steering system with priority function _______________________________ 115
Designing a steering system for centre-pivot steering _____________________________ 123

Exercises and worksheets: Mobile hydraulics, advanced level working hydraulics (TP 803)
Exercise 3-1: Examining a hydraulic system with load-sensing-controlled variable displacement pump
Exercise 3-2: Examining the load hold function _____________________________________________
Exercise 3-3: Remotely controlling proportional directional control valves using a hydraulic joystick __
Exercise 3-4: Setting a (volumetric) flow rate independent of load ______________________________
Exercise 3-5: Setting the volumetric flow rate using a load-sensing-controlled pump unit ___________
Exercise 3-6: Examining a load-sensing system with upstream pressure balance __________________
Exercise 3-7: Examining a load-sensing system with downstream pressure balance ________________

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133
143
151
159
169
179
191

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1
Examining performance for a controller using constant displacement pump
and fixed pressure limitation
Learning objectives
After completing this exercise:
you will be familiar with the relationship between pressure, flow rate and power output.
you will be able to calculate the power consumption of a hydraulic system.
you will know that flow division can lead to energy losses in a hydraulic system.
you will know that when using a constant displacement pump, non-decreasing volume flow leads to
energy loss.

Problem description
The motor speed of a wheel milling cutter is controlled using a flow control valve. The rotation of the motor
is only in one direction. The load acting on the motor changes depending on the soil conditions.
Examine how different load requirements affect the energy balance of the controls.

Positional sketch

Wheel saw, Bobcat, www.bobcat.eu

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

1.
2.
3.
4.
5.
6.

Parameters
When the hydraulic power unit is switched on, the motor will turn.
The load on the motor should be simulated using a proportional pressure-relief valve.

Project assignments
Set up the controller.
Familiarise yourself with the commissioning procedure.
Find out about the procedure when taking measurements in the electrical circuit.
Double check the controller configuration.
Measure the pressure and flow rate at different load pressures.
Calculate the power output of the pump unit; the effective power and the power loss based on the
measured values. Depict the calculated power output in the bar chart and evaluate the results.

Visual inspection
Continuous visual inspection for defects in tubing and hydraulic devices is an essential part of
hydraulic safety standards.

Work aids
Data sheets, operating instructions
Hydraulics textbook
Basics of mobile hydraulics (see attachment)

Name: __________________________________ Date: ____________

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

1. Setting up the controller

1B4

p2
P

1V4
1V3

1B3

p1

1B1

1V1
n

LS

P1

P2

q2

T
T

1B2

1A1

1V2

45 bar

q1

0Z1

LA

LA

60 bar

Circuit diagram

Note
The pressure-relief valve 1V4 is used to set load pressures.

Festo Didactic GmbH & Co. KG 574166

Name: __________________________________ Date: ____________

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

Quantity

Labelling

Designation

1B3, 1B4

Electronic pressure switch

1B1, 1B2

Flow sensor, coupled with hydraulic motor

1A1

Hydraulic motor

1V3

Flow control valve

1V1, 1V4

Pressure-relief valve

1V2

Shut-off valve

4-way manifold plate with pressure gauge

Tubing line

0Z1

Hydraulic power unit with constant displacement pump

Equipment list

Note
You will need the following in order to perform the measurements.
1 power pack 24 V DC
2 digital multimeters

Set up the controller.

Observe the following points when setting up the controller:

Set the pressure-relief valve for the constant displacement pump of the hydraulic power unit to a
pressure of 60 bar (6 MPa) before setting up the control.
Use the circuit diagram.
Designate the components.
Connecting tubing lines
Never connect or disconnect tubing lines when the hydraulic power unit is running, or while under
pressure!
Couplings must be connected in the unpressurised state.
Set the coupling socket vertically onto the coupling nipple!
The coupling socket and the coupling nipple must not be fitted askew.
Selecting and laying tubing lines
Select the tubing line length such that adequate leeway is available
in order to accommodate changes in length which result from pressure.
Avoid mechanical stressing of the tubing line.
Do not bend the tubing line into a radius of less than its specified minimum bending radius
of 51 mm.
Do not twist the tubing line during installation.
Make sure that tubing lines do not become kinked.
Mark the completed tubing connections in the hydraulic circuit diagram.

Name: __________________________________ Date: ____________

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

2. Becoming familiar with the commissioning procedure

Information
During practice operation and for industrial maintenance purposes, safe commissioning is
undertaken at low pressure which is then increased up to the maximum value. This is possible with
either a pressure-relief valve or a pump recirculation circuit. At low pressure, leaks can be safely
detected after device replacement, for example.
Commissioning procedure with pump recirculation circuit
1. Switch to pump recirculation by opening the shut-off valve.
2. With electro-hydraulic controls, activate the electrical 24 V DC control voltage.
3. Switch the hydraulic pump on.
4. Slowly close the shut-off valve until a circulating pressure of approximately 15 bar prevails.
Immediately set the pump back to recirculation in the event of leaks.
5. Run the sequence once and watch for leaks.
6. Fully close the shut-off valve and set the pressure limit at the pressure-relief valve of the
hydraulic power unit to the specified value.

3. Finding out about the procedure when taking measurements in the electrical circuit

Safety instructions

Before measuring, make sure that the section of the controller in which you intend to take
measurements only works with an electrical voltage of no greater than 24 V DC!
Measurements within sections of the controller which function with higher voltages (e.g. 230 V)
may only be performed by persons who have received appropriate training or instruction.
Incorrect performance of this measurement is life endangering!
Observe the safety precautions for working with electrical power!

Festo Didactic GmbH & Co. KG 574166

Name: __________________________________ Date: ____________

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

Information
Procedure for performing measurements in the electrical circuit
1.
2.
3.

Switch off supply power to the electrical circuit.

Select the desired operating mode at the multimeter (e.g. direct current measurement).
Connect the measuring instrument with correct polarity when measuring direct current/
direct voltage.
4. Select the largest measuring range.
5. Switch supply power to the electrical circuit back on.
6. Watch the display and switch to increasingly smaller measuring ranges step-by-step.
7. Read the value from the display after arriving at the smallest possible measuring range.

4. Double checking the controller setup

Observe the following points when commissioning the controller:
Before commissioning, make sure that all tank lines have been connected and that all couplings have
been securely fitted.
Fully close the flow control valve 1V3.
Fully open both pressure-relief valves 1V1 and 1V4.
Switch to pump recirculation by opening shut-off valve 1V2.
Switch off the 24 V DC electrical supply voltage for the flow sensors and pressure switches.
Note
You will find information on the sensors in the operating instructions.
When using the analogue output of the pressure switch, make sure it is set to between 0-10 V.

Switch the hydraulic power unit on.

Slowly close the shut-off valve 1V2. The entire pump unit delivery rate flows at low pressure through the
pressure-relief valve 1V1 to the tank.
Immediately set the pump back to recirculation in the event of leaks.
Set the pressure at the pressure-relief valve 1V1 to 45 bar.
Perform the measurement tasks.

5. Measuring pressure and flow rate at different load pressures

Execution
Set the pressure-relief valve 1V1 to 45 bar. Set the values indicated in the table for the flow control
valve 1V3 and the pressure-relief valve 1V4. Measure the pressure and flow rate for these values.

Name: __________________________________ Date: ____________

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

Set the values indicated in the table. Enter the measured pressure and flow rate values into the table.

Load case

Valve specifications

Pump pressure
p1 [bar]

Flow rate
q1 [l/min]

Load pressure
p2 [bar]

Flow rate
q2 [l/min]

1V3: open
1V4: Minimum pressure

1V3: open

1V4: Minimum pressure

30

0.5

25

30
0.5

Measurement log

Notes
Fully open the flow control valve 1V3 before dismantling the controller.
Fully open the pressure-relief valves 1V1 and 1V4 before dismantling.

6. Calculating the pumping power, effective power and power loss

Information
The formula for calculating the power in the hydraulic system when using the indicated physical
units is:

q p
600

P
q
p

Power [kW]
Flow rate [l/min]
Pressure [bar]

Power output of the pump unit: PP

q p
PP 1 1
600
PP Power output of the pump unit [kW]:
q1 Flow volume of the pump unit [l/min]
p1 Pump pressure [bar]

Festo Didactic GmbH & Co. KG 574166

Name: __________________________________ Date: ____________

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

Effective power (output of the consuming device): PL

q p
PL 2 2
600
PL Output of the consuming device [kW]
q2 Flow rate to the consuming device [l/min]
p2 Load pressure [bar]
Power loss: PV
PV PP PL
PV Power loss [kW]

a) Calculate the pumping power, effective power and power loss for the load cases a to f (see workbook 4).
Enter the values to the table.
Load case

Pumping power
PP [kW]

Effective power
PL [kW]

Power loss
PV [kW]

a
b
c
d
e
f

Performance for the load cases a to f

10

Name: __________________________________ Date: ____________

Festo Didactic GmbH & Co. KG 574166

Exercise 1-1 Examining performance for a controller using constant displacement pump and fixed pressure limitation

b) Transfer the performance values for load cases a to f to a bar chart.

0.35
kW
0.25
0.2
0.15
0.1
PP
0.05
0

PL
PV
PP PL PV
a

PP PL PV
b

PP PL PV
c

PP PL PV
d

PP PL PV
e

PP PL PV
f

PP Pumping power
PL Effective power
PV Power loss
Performance of the system with constant displacement pump and pressure limitation with different load cases a to f

c)

When is power loss PV particularly high? Give reasons for your answer.

Festo Didactic GmbH & Co. KG 574166

Name: __________________________________ Date: ____________

11

Contents
Fundamentals of mobile hydraulics
1

Introduction _____________________________________________________________________ I-5

2
2.1
2.2
2.3

Fundamentals of hydraulics ________________________________________________________ I-7

Fundamentals of pressure and flow control valves ______________________________________ I-7
Pressure drop ___________________________________________________________________ I-10
Heat generation due to pressure drop _______________________________________________ I-13

3
3.1
3.2
3.2.1
3.2.2
3.3
3.4
3.5

Closed hydraulic circuit (hydrostatic system) _________________________________________

Structure of a closed hydraulic circuit ________________________________________________
Hydraulic pumps for closed hydraulic circuits _________________________________________
Mechanical adjustment of hydraulic pump ____________________________________________
Hydraulic adjustment of hydraulic pump _____________________________________________
Feed pumps_____________________________________________________________________
Flushing valves __________________________________________________________________
Shock valves ____________________________________________________________________

I-15
I-15
I-17
I-17
I-18
I-20
I-20
I-21

4
4.1
4.1.1
4.1.2
4.2
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.2.6

Load-sensing systems ____________________________________________________________

Features of load-sensing systems ___________________________________________________
Open-centre load-sensing systems __________________________________________________
Closed centre load sensing systems:_________________________________________________
Energy efficiency of hydraulic pressure supply system __________________________________
Energy loss _____________________________________________________________________
Pressureless pump recirculation circuit ______________________________________________
Volumetric flow control in systems with a constant-displacement pump ____________________
Volumetric flow control in systems with a variable-displacement pump ____________________
Volumetric flow control in open-centre load-sensing systems_____________________________
Volumetric flow control in closed-centre load-sensing systems ___________________________

I-23
I-23
I-23
I-25
I-30
I-30
I-32
I-34
I-36
I-38
I-40

5
5.1
5.2
5.3

Variable-displacement pumps _____________________________________________________

Types of variable-displacement pumps _______________________________________________
Vane pump _____________________________________________________________________
Axial piston pump ________________________________________________________________

I-42
I-42
I-42
I-44

6
6.1
6.2

Two-pump system with shut-off valve _______________________________________________ I-46

Requirements for a pump system for mobile machines __________________________________ I-46
Example of a two-pump system with shut-off valve _____________________________________ I-47

Festo Didactic GmbH & Co. KG 574166

I-1

I-2

7
7.1
7.2
7.3
7.4

Flow-dividing valves _____________________________________________________________

Synchronous running of drives _____________________________________________________
Flow divider valve (50/50 slide valve) ________________________________________________
Rotary flow divider valve __________________________________________________________
Rotary flow divider valve for pressure boost ___________________________________________

I-48
I-48
I-48
I-50
I-51

8
8.1
8.2
8.3
8.4
8.4.1
8.4.2
8.5
8.5.1
8.5.2
8.5.3
8.6

Valve manifolds for mobile hydraulics_______________________________________________

Structure of valve manifolds _______________________________________________________
Circuit symbols for proportional directional control valves in valve modules _________________
Structure of valve modules ________________________________________________________
Valve slides of proportional directional control valves___________________________________
Design of valve slides _____________________________________________________________
Influence of control notches on flow characteristics ____________________________________
Input module of a valve manifold ___________________________________________________
Structure of an input module _______________________________________________________
Input module in conjunction with an open-centre valve module ___________________________
Input module in conjunction with a closed-centre valve module ___________________________
Shock and replenishing valve ______________________________________________________

I-49
I-53
I-55
I-56
I-57
I-57
I-58
I-59
I-59
I-60
I-61
I-62

9
9.1
9.2
9.3
9.4
9.5

Circuits with open-centre valves ____________________________________________________

Open-centre valves _______________________________________________________________
Structure of an open-centre 6/3-way valve ____________________________________________
Parallel circuit ___________________________________________________________________
Tandem circuit __________________________________________________________________
Series circuit ____________________________________________________________________

I-64
I-64
I-66
I-69
I-70
I-71

10
10.1
10.2
10.3

Non-load-dependent volumetric flow control with proportional valves ____________________

Proportional flow control valve _____________________________________________________
Upstream pressure balance valve ___________________________________________________
Downstream pressure balance valve _________________________________________________

I-72
I-72
I-74
I-78

11
11.1
11.2
11.3
11.4

Holding and safe lowering of loads _________________________________________________

Example of application ____________________________________________________________
Piloted non-return valve ___________________________________________________________
Pressure-relief valve ______________________________________________________________
Counterbalance valve _____________________________________________________________

I-82
I-82
I-83
I-84
I-85

12
12.1
13.2
13.3

Hydraulic piloting _______________________________________________________________

Hydraulic piloting with a joystick ____________________________________________________
Hydraulic joystick (manually-operated piloting) ________________________________________
Electronic joystick (electrohydraulic piloting) __________________________________________

I-88
I-88
I-88
I-90

Festo Didactic GmbH & Co. KG 574166

13
13.1
13.2
13.3
13.4
13.5
13.6
13.7

Prioritisation of load devices ______________________________________________________

Necessity for prioritisation of load devices ____________________________________________
Pressure sequence valve __________________________________________________________
Prioritisation through circuit design _________________________________________________
Directional control valve with prioritisation ___________________________________________
Static priority valve _______________________________________________________________
Dynamic priority valve ____________________________________________________________
3-way flow control valve ___________________________________________________________

I-92
I-92
I-92
I-93
I-94
I-94
I-95
I-96

14
14.1
14.2
14.2.1
14.2.2
14.3
14.3.1
14.3.2
14.3.3
14.3.4
14.4
14.4.1
14.4.2

Hydrostatic steering _____________________________________________________________ I-98

Structure and features of hydrostatic steering _________________________________________ I-98
Structure of steering valves ________________________________________________________ I-98
Rotary slide valve and bushing _____________________________________________________ I-99
Metering pump (Orbitrol pump)____________________________________________________ I-100
Types of steering valves __________________________________________________________ I-101
Open-centre steering valves ______________________________________________________ I-101
Closed-centre steering valves _____________________________________________________ I-102
Load-sensing steering valves ______________________________________________________ I-103
Reaction and non-reaction steering valves ___________________________________________ I-103
Types of steering systems ________________________________________________________ I-104
Ackermann steering system with steering knuckles ____________________________________ I-105
Articulated steering system _______________________________________________________ I-105

Picture credits ________________________________________________________________________ I-107

Festo Didactic GmbH & Co. KG 574166

I-3

I-4

Festo Didactic GmbH & Co. KG 574166

1 Introduction

Example of a vehicle with mobile hydraulics

There are a number of special conditions which occur in mobile hydraulics but not in industrial hydraulics:
No regular working cycle
In industrial hydraulic systems, the force acting on the drive is normally constant. With mobile systems,
on the other hand, the operative force is extremely variable. For hydraulic applications with variable
force and speed, the use of a constant-displacement pump and a maximum pressure safety valve is not
an economic solution.
Generally no external energy supply
Harsh environmental conditions
These may include large temperature differences, dust and impacts.
Limited installation space
Limited weight
From the above we derive the requirements for mobile hydraulic systems:
Efficiency in energy consumption
The most important consideration in mobile systems is efficiency: As mobile machines generally move
independently from any power source, the power supply is limited. In most cases, the only power
source is an internal combustion engine with a limited fuel supply.
Compact design
The individual components of mobile machines, such as tanks, pumps, motors, cylinders and valves
should be kept as small and light as possible. In order to achieve the desired performance with small
components, it is necessary to increase the pressure. Higher pressure in turn demands valves with close
tolerances in order to minimise leakage losses. Close-tolerance valves and the high performance
density make it necessary to pay more attention to filtering and cooling the hydraulic fluid.
Robust design
The components are subjected to wide temperature fluctuations. Moreover, the drives are frequently
subject to wide and rapid fluctuations in force. External drives and supply-line hoses are directly
exposed to dirt and collisions, for example with excavated material. This means that the hydraulic
components must be of robust design.

Festo Didactic GmbH & Co. KG 574166

I-5

1 Introduction

The following hydraulic systems are used in mobile machines:

Closed hydrostatic transmission, e.g. for travel operation
Working hydraulics
Steering system
Braking system
Two types of hydraulic circuits are used in mobile machines
Open circuit
In an open circuit, a pump delivers fluid from a tank to load devices. From the load devices, the fluid
then flows back to the tank. Open circuits are used above all for working hydraulics.
Closed circuit
In a closed circuit, a pump delivers fluid to load devices. There are generally no flow control or
directional control valves between the pump and the load devices. From the load devices, the fluid then
flows back directly to the pump..
Often the pump acts as a controller for both the volume and direction of the flow of fluid. Closed circuits
are used mostly for travel drives
There are of course also combinations of the two types of circuit within one machine. In these cases, the
vehicle engine drives several pumps. The main pump in this case is the pump for the closed drive circuit,
while the auxiliary pumps operate with open circuits and supply the working hydraulic systems.

I-6

Festo Didactic GmbH & Co. KG 574166