Hydraulics Workbook

8/3/2019 Hydraulics Workbook

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Learning System for Automation

094468(04/01)

Hydraulics

Workbook Basic Level


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TP501 Festo Didactic

Authorised applications and liability

The Learning System for Automation and Communication has been de-veloped and prepared exclusively for training in the field of automationand communication. The training organization and / or trainee shall en-sure that the safety precautions described in the accompanying Techni-cal documentation are fully observed.

Festo Didactic hereby excludes any liability for injury to trainees, to thetraining organization and / or to third parties occurring as a result of theuse or application of the station outside of a pure training situation, un-less caused by premeditation or gross negligence on the part of FestoDidactic.

Order no.: 094468Description: TEACHW. HYDRAUL.Designation: D.S501-C-SIBU-GBEdition: 04/01Layout: 30.04.2001, OCKER Ingenieurbro

Graphics: OCKER IngenieurbroAuthor: D. Waller, H. Werner

Copyright by Festo Didactic GmbH & Co., D-73770 Denkendorf 2001

The copying, distribution and utilization of this document as well as thecommunication of its contents to others without expressed authorizationis prohibited. Offenders will be held liable for the payment of damages.

All rights reserved, in particular the right to carry out patent, utility modelor ornamental design registrations.

Parts of this training documentation may be duplicated, solely for train-

ing purposes, by persons authorised in this sense.


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Preface

Festo Didactics Learning System for Automation and Communicationsis designed to meet a number of different training and vocational re-quirements. The Festo Training Packages are structured accordingly:

T Basic Packages provide fundamental knowledge on a wide range oftechnologies.

T Technology Packages deal with important areas of open-loop andclosed-loop control technology.

T Function Packages explain the basic functions of automation sys-tems.

T Application Packages provide basic and further training closely ori-ented to everyday industrial practice.

Technology Packages deal with the technologies of pneumatics, elec-tropneumatics, programmable logic controllers, automation with PCs,hydraulics, electrohydraulics, proportional hydraulics and applicationtechnology (handling).

Fig. 1:

Hydraulics 2000 i.e. mobile workstation

Mounting frame

Profile plateU = 230V~

p = 6 MPa

Storage tray


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The modular structure of the Learning System permits applications to beassembled which go beyond the scope of the individual packages. It ispossible, for example, to use PLCs to control pneumatic, hydraulic andelectrical actuators.

All training packages have an identical structure:

T Hardware

T Courseware

T Software

T

Courses

The hardware consists of industrial components and installations,adapted for didactic purposes.

The courseware is matched methodologically and didactically to thetraining hardware. The courseware comprises:

T Textbooks (with exercises and examples)

T Workbooks (with practical exercises, explanatory notes, solutions anddata sheets)

T OHP transparencies and videos (to bring teaching to life)

Teaching and learning media are available in several languages. Theyhave been designed for use in classroom teaching but can also be usedfor self-study purposes.

In the software field, computer-based training programs and program-ming software for programmable logic controllers are available.

Festo Didactics range of products for basic and further training is com-pleted by a comprehensive selection of courses matched to the contentsof the technology packages.


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Latest information about the technology package TP501.

New in Hydraulic 2000:

T Industrial components on the profile plate.

T Exercises with exercise sheets and solutions, leading questions.

T Fostering of key qualifications:Technical competence, personal competence and social competenceform professional competence.

T

Training of team skills, willingness to co-operate, willingness to learn,independence and organisational skills.

Aim Professional competence

Content

Part A Course Exercises

Part B Fundamentals Reference to the text book

Part C Solutions Function diagrams, circuits, descriptions ofsolutions and quipment lists

Part D Appendix Storage tray, mounting technologyand datasheets


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Table of contents

Introduction 11

Notes on safety 13

Notes on operation 13

Technical notes 14

Training contents 17

Equipment set for Hydraulics Basic Level 19

Component / exercise table for TP 501 24

Section A Course

Exercise 1: Automatic lathePump characteristic A-3

Exercise 2: Package lifting devicePressure relief valve characteristic A-7

Exercise 3: Drawing pressHydraulic resistances A-11

Exercise 4: Calender feeding deviceSingle-acting cylinder (basic circuit) A-15

Exercise 5: Hardening furnaceSingle-acting cylinder(measurement and calculation) A-19

Exercise 6: Furnace door controlDouble-acting cylinder A-23

Exercise 7: Conveyor tensioning device4/3-way valve with bypass to pump A-29

Exercise 8: Cold-store doorAccumulator A-33

Exercise 9: Rotary machining stationFlow control valve and counter-holding A-37

Exercise 10: Painting boothFlow control valve characteristic A-41


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Exercise 11: Embossing machineOne-way flow control valve and counter-holding A-45

Exercise 12: Surface grinding machineDifferential circuit A-49

Exercise 13: Drilling machinePressure regulator A-55

Exercise 14: Bulkhead doorHydraulic clamping of a cylinder A-59

Exercise 15: Ferry loading rampFlow control valve in inlet and outlet lines A-63

Exercise 16: Skip handlingVarying load A-69

Exercise 17: Bonding pressComparison of pressure regulator and pressure relief valve A-73

Exercise 18: Assembly devicePressure sequence circuit,displacement-step diagram A-77

Exercise 19: Assembly deviceCalculation of pressure and time A-81

Exercise 20: Tipping containerElectrohydraulics A-85

Section B - Fundamentals


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Section C Solutions

Solution 1: Automatic lathe C-3

Solution 2: Package lifting device C-7

Solution 3: Drawing press C-11

Solution 4: Calender feeding device C-15

Solution 5: Hardening furnace C-19

Solution 6: Furnace door control C-23

Solution 7: Conveyor tensioning device C-27

Solution 8: Cold-store door C-33

Solution 9: Rotary machining station C-37

Solution 10: Painting booth C-41

Solution 11: Embossing machine C-45

Solution 12: Surface grinding machine C-49

Solution 13: Drilling machine C-59

Solution 14: Bulkhead door C-65

Solution 15: Ferry loading ramp C-69

Solution 16: Skip handling C-73

Solution 17: Bonding press C-77

Solution 18: Assembly device C-79

Solution 19: Calculation for an assembly device C-83

Solution 20: Tipping container C-85

Section D Appendix

Storage tray D-3

Mounting systems D-4

Sub-base D-6

Coupling system D-7

Data sheets ...


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Introduction

This workbook forms part of Festo Didactics Learning System forAutomation and Communications. The Technology Package Hydrau-lics, TP500, is designed to provide an introduction to the fundamentalsof hydraulic control technology. This package comprises a basic leveland an advanced level. The basic level package TP501 teaches basicknowledge of hydraulic control technology, while the advance levelpackage TP502 builds on this.

The basic level hydraulic exercises are designed to be carried out with

manual actuation. It is, however, also possible to use electrical actua-tion. The hydraulic components have been designed to provide the fol-lowing:

T Easy handling

T Secure mounting

T Environmentally-friendly coupling system

T Compact component dimensions

T Authentic measuring methods

We recommend the following for the practical execution of the exer-cises:

T Hydraulic components: Equipment set TP501

T One hydraulic power pack

T A number of hose lines

T A profile plate or a suitable laboratory trolley

T A measuring set with the appropriate sensors


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This workbook provides knowledge of the physical interrelationships andthe most important basic circuits in hydraulics. The exercises deal withthe following:

T Plotting of characteristics for individual components

T Comparison of the use of different components

T Assembly of various basic circuits

T Use of basic hydraulics equations

The following technical equipment is required for safe operation of thecomponents:

T A hydraulic power pack providing an operating pressure of 60 barand a flow rate of 2 l/min

T An electrical power supply of 230V AC for the hydraulic power pack

T A power supply unit with an output of 24V DC for solenoid-actuatedvalves

T A Festo Didactic profile plate for mounting the components

The theoretical background is described in the Hydraulics Basic Leveltextbook TP501. Technical descriptions of the components used aregiven in the data sheets in Part D of this workbook.

Festo Didactic offers the following further training material for hydraulics:

T Magnetic symbols

T Hydraulics slide rule

T Set of OHP transparencies

T Transparent models

T

Interactive videoT Symbol library


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Notes on safety

Observe the following in the interests of your own safety:

T Exercise care when switching on the hydraulic power pack. Cylindersmay advance unexpectedly!

T Do not exceed the maximum permissible operating pressure (seedata sheets).

T Observe all general safety instructions (DIN 58126 and VDE 100).

Notes on operation

Always work in the following sequence when assembling a hydrauliccircuit.

1. The hydraulic power pack and electrical power supply must beswitched off during the assembly of the circuit.

2. All components must be securely fitted to the profile plate, i.e. se-curely snap-fitted or bolted down.

3. Check that all return lines are connected and all hose lines are se-curely fitted.

4. Switch on the electrical power supply first and then the hydraulicpower pack.

5. Before dismantling the circuit, ensure that pressure in hydraulic com-ponents has been released:

Couplings must be connected and disconnected only underzero pressure!

6. Switch off the hydraulic power pack first and then the electricalpower supply.


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Technical notes

Observe the following in order to ensure safe operation.

T The hydraulic power pack PN 152962 incorporates an adjustablepressure relief valve. In the interests of safety, the pressure is limitedto approx. 60 bar (6 MPa).

T The maximum permissible pressure for all hydraulic components is120 bar (12 MPa).

The operating pressure should not exceed 60 bar (6 MPa).

T In the case of double-acting cylinders, the pressure intensificationeffect may produce an increased pressure proportional to the arearatio of the cylinder. With an area ratio of 1:1.7 and an operatingpressure of 60 bar (6 MPa), this increased pressure may be over100 bar (10 MPa)!

T If connections are detached under pressure, the non-return valve inthe coupling may cause pressure to become trapped in the valve orother component concerned. The pressure relieving device PN152971 can be used to release this pressure. Exception: This is notpossible in the case of hose lines and non-return valves.

T All valves, other components and hose lines are fitted with self-closing quick-release couplings. This prevents the accidental spillage

of hydraulic fluid. In the interests of simplicity, these couplings are notshown in circuit diagrams.

Throttle valve Hose Shut-off valve

Fig. 2:Pressure intensification

Fig. 3:Simplified drawing of

self-closing couplings


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T It is frequently necessary when assembling a control circuit to modifythe given circuit diagram. Within the scope of the equipment set inthis Training Package, the following alternative solutions are possible:

T Plugs can be used to change the function of directional control valves(Figs. 4 and 5).

T Directional control valves with different normal positions can be used(Fig. 6).

T Solenoid-actuated valves can be used in place of hand lever valves(Fig. 7).

2/2-way valve 3/2-way valve

4/2-way valve 4/2-way valve

Circuit diagram Practical assembly

Fig. 4:Circuit diagram

Fig. 5:Practical assembly

Fig. 6:Directional control valveswith variousnormal positions

Fig. 7:Solenoid-actuateddirectional control valve


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Flow rate sensor

The flow rate sensor consists of:

T A hydraulic motor, which converts the flow rate q into a rotary speedn.

T A tachogenerator, which produces a voltage V proportional to therotary speed n.

T A universal display unit, which converts the flow rate q into l/min. Theuniversal display should be set to sensor no. 3 for this purpose.

q Hydraulicmotor

n Tacho-generator

V Universaldisplay

qFig. 8:Block circuit diagram

Fig. 9:Circuit diagrams,

hydraulic and electrical

Fig. 10:Connecting up the

universal display

Battery operation

External power supply


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Training contents

T Characteristics of valves and other components.

T Uses of individual valves and other components.

T Comparison of uses and functions of different valves and other com-ponents.

T Measurement of variables such as pressure, flow rate and time.

T Control of pressure and speed.

T Calculations of area ratios, forces, power and speed.

T Basic physical principles of hydraulics.

T Use of basic hydraulics equations.

T Understanding and drafting of circuit diagrams.

T Drafting of displacement/step diagrams.

T Use of symbols in accordance with DIN/ISO 1219.

T Assembly and commissioning of control circuits, including fault-finding.

T

Assessment of energy consumption.T Basic hydraulic circuits such as a pressure sequence circuit, a by-

pass circuit to the pump, a differential circuit, circuits with flow controlvalves in the inlet, outlet and bypass, circuits with counter-holdingand bypass circuits with a non-return valve.


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Exercise Training aims

1 Drawing a pump characteristic.

2 Drawing a characteristic for a pressure relief valve.

3 Measuring flow resistances.

4 Application of a non-return valve.Use of a 2/2-way valve to control a single-acting cylinder.

5 Application of a 3/2-way valve.Determination of times

6 Application of a 4/2-way valve.

Determination of times

7 Application of a 4/3-way valve.Use of a pilot-operated non-return valve.

8 Use of a hydraulic accumulator as a power source.Use of accumulator to power advance and return strokes of cylinder afterpump is switched off.

9 Application of a 2-way flow control valve.Assembly of a counter-pressure circuit.

10 Plotting of characteristic for a 2-way flow control valve.Comparison between this valve and a throttle valve.

11 Application of a one-way flow control valve.

Difference between flow control valve and throttle valve on the basis of aconcrete application.

12 Design and mode of operation of a differential circuit.Influence of piston areas on pressures

13 Design of a control circuit with reduced output pressure.Explanation of mode of operation of a 3-way pressure regulator.

14 Hydraulic clamping with a double-acting cylinder.Comparison of circuits with and without counter-holding.

15 Speed control circuit with tractive load.Comparison of circuits with flow control valves in the inlet line and outletline respectively.

16 Circuit for a double-acting cylinder with a varying load.

17 Specification of pressure for a double-acting cylinder.Choice of either a pressure relief valve or a pressure regulator

18 Pressure sequence circuit.Drawing of a displacement/step diagram

19 Calculation of forces associated with a double-acting cylinderCalculation of advance-stroke time of a cylinder piston.

20 Electrohydraulic control circuit.

List of training aims


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Equipment set for Hydraulics Basic Level

Description Order No. Qty.

Pressure gauge 152841 3

Throttle valve 152842 1

One-way flow control valve 152843 1

Shut-off valve 152844 1

Non-return valve, opening pressure 1 bar 152845 1

Non-return valve, opening pressure 5 bar 152846 1

Branch tee 152847 7

Pressure relief valve 152848 1

Pressure relief valve, piloted 152849 1

Pressure regulator 152850 1

Flow control valve 152851 1

Non-return valve, hydraulically piloted 152852 1

Double-acting cylinder 152857 1

Hydraulic motor 152858 1

Diaphragm accumulator 152859 1

Loading weight, 9 kg 152972 1

4/2-way hand lever valve 152974 1

4/3-way hand lever valve, recirculation mid-position 152977 1

TP501, PN 080246


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Stop-watch 151504 1

4/3-way hand lever valve, closed in mid-position 152975 1

4/3-way hand lever valve, relieving mid-position 152976 1

Relay, 3-fold 162241 1

Signal input unit, electrical 162242 1

Flow-rate sensor 183736 1

4/2-way solenoid valve 167082 1

4/3-way solenoid valve, closed in mid-position 167083 1

4/3-way solenoid valve, relieving mid-position 167084 1

4/3-way solenoid valve, recirculating mid-position 167085 1

Universal display 183737 1

Pressure sensor 184133 1


Profile plate, large 159411 1

Schlauchleitung, 600 mm 152960 12

Hydraulik-Aggregat 152962 1

Hose line, 1000 mm 152970 4

Pressure relieving device 152971 1

Protective cover (for weight, 9kg) 152973 1

Power supply unit, 24 V, 4.5 A 162417 1

Cable set with safety plugs 167091 1

Additional equipment

Accessories


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Description Symbol

Pressure gauge

Throttle valve

One-way flow control valve

Shut-off valve

Non-return valve

Branch tee

Pressure relief valve

Pilot-operated pressure relief valve

Pressure regulator

Flow control valve

Piloted non-return valve

Double-acting cylinder

Symbols forequipment set TP501


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Description Symbol

Hydraulic motor

Diaphragm accumulator, detailed

Diaphragm accumulator, simplified

Weight

4/2-way hand lever valve

4/2-way solenoid valve

4/3-way hand lever valve, closed in mid-position

4/3-way hand lever valve, relieving mid-position

4/3-Wege-Handhebelventil mit Umlaufstellung



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Description Symbol

4/3-way solenoid valve, closed in mid-position

4/3-way solenoid valve, relieving mid position

4/3-way solenoid valve, recirculating mid-position

Hose line

Hydraulic-power pack, detailed

Hydraulic power pack, simplified

Pressure sensor

Flow rate sensor

Hydraulic motor with tachogenerator



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Component / exercise table for TP 501

Exercises

Description 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Pressure gauge 1 1 3 1 3 1 1 2 5 3 5 3 4 3 3 3 3 2

Throttle valve 1 1

One-way flow control valve 1 1 1 1

Shut-off valve 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Non-return valve, 1 bar 1 1 1 1 1 1 1 1Non-return valve, 5 bar 1 1 1 1 1 1

Branch tee 2 3 4 3 2 3 3 6 2 4 4 5 4 4 4 5 7 2

Pressure relief valve *) 1 2 1 1 1 1 1 2 2 2 1 1 2 2 3 2 3 1

Pressure relief valve, piloted (1) (1) (1) (1) (1) (1) (1) (1) (1) (1)

Pressure regulator 1 1

Flow control valve 1 1 1 1 1 1

Piloted non-return valve 1 1

Cylinder, double-acting 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Hydraulic motor 1

Diaphragm accumulator 1

Weight 1 1 1 1

4/2-way hand lever valve 1 1 1 1 1 1 1

4/3-way hand lever valverecirculating mid-position 1 1 1 1 1 1 1 1

Hydraulic power pack 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Hose line, 600 mm 3 5 5 6 5 4 7 5 9 4 12 5 12 10 11 8 5 12 4

Hose line, 1000 mm 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 4 2

Stop-watch 1 1 1 1 1 1 1 1

Pressure sensor (2) 2 2

Flow-rate sensor 1 1 1 1 1

Universal display 1 1 1 1 1

Power supply unit 1 1 1 1 1 1

*) If a sufficient number of directly-controlled pressure relief valves is not available,the pilot-operated pressure relief valve can also be used.


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Electrical equipment for exercise 20


4/3-way solenoid valve, relieving mid-position 167084 1

Signal input unit, electrical 162242 1

Relay, 3-fold 162241 1

Cable set 167091 1

The exercises appear in Section A of the workbook, with solutions tothese in Section C. The methodological structure is the same for all ex-ercises.

The exercises in Section A are structured as follows:

T Subject

T

Title

T

Training aim(s)

T

Problem definition

T

Exercise

T

Positional sketch

A worksheet then follows for use in carrying out the exercise.

The solutions in Section C contain the following:

T Hydraulic circuit diagram

T

Practical assembly

T

Component list

T

Solution description

T

Evaluation

T

Conclusions

Methodologicalstructure of exercises


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A-1

Section A Course

Exercise 1: Automatic lathePump characteristic A-3

Exercise 2: Package lifting devicePressure relief valve characteristic A-7

Exercise 3: Drawing pressHydraulic resistances A-11

Exercise 4: Calender feeding device

Single-acting cylinder (basic circuit) A-15

Exercise 5: Hardening furnaceSingle-acting cylinder(measurement and calculation) A-19

Exercise 6: Furnace door controlDouble-acting cylinder A-23

Exercise 7: Conveyor tensioning device4/3-way valve with bypass to pump A-29

Exercise 8: Cold-store doorAccumulator A-33

Exercise 9: Rotary machining stationFlow control valve and counter-holding A-37

Exercise 10: Painting boothFlow control valve characteristic A-41

Exercise 11: Embossing machineOne-way flow control valve and counter-holding A-45

Exercise 12: Surface grinding machineDifferential circuit A-49

Exercise 13: Drilling machine

Pressure regulator A-55

Exercise 14: Bulkhead doorHydraulic clamping of a cylinder A-59


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A-2

Exercise 15: Ferry loading rampFlow control valve in inlet and outlet lines A-63

Exercise 16: Skip handlingVarying load A-69

Exercise 17: Bonding pressComparison of pressure regulator and pressure relief valve A-73

Exercise 18: Assembly devicePressure sequence circuit,

displacement-step diagram A-77Exercise 19: Assembly device

Calculation of pressure and time A-81

Exercise 20: Tipping containerElectrohydraulics A-85


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A-3Exercise 1

Hydraulics

Automatic lathe

T To teach the student how to draw the characteristic curve for a pump

T Drawing the hydraulic circuit diagram

T Practical assembly of the circuit

T Determining the various measured values and entering them into thetable

T Drawing the characteristic curve for the pump

T Drawing conclusions

Subject

Title

Training aim

Problem definition


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A-4Exercise 2

The main spindle on an automatic lathe is driven by a hydraulic motor,while a hydraulic cylinder is used to execute a feed movement of theworkpiece slide. It has been established that the specified speed is nolonger reached during the processing cycle. The pump characteristiccurve is therefore to be evaluated.

Exercise

Positional sketch


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A-5Exercise 1

EXERCISE SHEET

System pressure p 15 20 25 30 35 40 45 50 bar

Flow rate q l/min

How does the flow rate change as the pressure increases?

Evaluation

Pump characteristic

Conclusion


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A-6Exercise 2


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A-7Exercise 2

Hydraulics

Package lifting device

T To teach the student how to draw the characteristic for apressure relief valve



T Setting a maximum pressure of 50bar

T Establishing the opening pressure of the pressure relief valve

T Determining the various measured values and entering theminto the table

T Drawing the pressure/flow rate characteristic


Subject

Title

Training aim

Problem definition


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A-8Exercise 2

Owing to a change in the production process, a package lifting device isnow required to lift heavier packages than those for which it was origi-nally designed. It has been observed that the stroke speed is now lower.Using the pressure/flow rate characteristic for the pressure relief valve,determine the pressure at which flow diversion of the pump output be-gins.

Exercise

Positional sketch

1A


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A-9Exercise 2

EXERCISE SHEET

Working pressure p 35 40 42.5 45 47.5 50 bar

Flow rate q l/min

How great is the difference between the opening pressure and maxi-mum pressure?

Evaluation

Characteristic forpressure relief valve

Conclusion


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A-10Exercise 2


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A-11Exercise 3

Hydraulics

Drawing press

T To teach the student how to measure flow resistances



T Setting a constant flow rate

T Measuring the flow resistances


Subject

Title

Training aim

Problem definition


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A-12Exercise 3

A drawing press is used to shape metal workpieces. Following modifica-tion of the hydraulic system, the workpieces are no longer dimensionallyaccurate. The reason for this may be that the required press pressure isnot being reached. Use a special test set-up to measure the hydraulicresistance of the components used.

Exercise

Positional sketch


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A-13Exercise 3

EXERCISE SHEET

p0Z3 = Pressure upstream of component

p0Z4 = Pressure downstream of component

Component Flow rate q

l/min

Pressurep0Z3bar

Pressurep0Z4bae

Pressuredifference

pbar

Pressure reliefvalve,fully open

2

1

Throttle valve,fully open

2

1

4/2-way valve,P > A

2

1

4/3-way valve,

P > A

2

1

How does the pressure difference change when the flow rate is dou-bled?

Evaluation

Values table

Conclusion


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A-14Exercise 3


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A-15Exercise 4

Hydraulics

Calender feeding device

T To familiarise the student with the applications of a non-return valve

T To show the activation of a single-acting cylinder using a 2/2-wayvalve



T Evaluation of this circuit

Subject

Title

Training aim

Problem definition


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A-16Exercise 4

Rolls of paper are lifted into a calender by a lifting device. The liftingdevice is driven by a plunger cylinder (single-acting cylinder). When thehydraulic power pack is switched on, the pump output flows directly tothe cylinder. A 2/2-way valve, which is closed in its normal position, isfitted in a branch line leading to the tank. A non-return valve is used toensure that the pump is protected against the oil back-pressure. A pres-sure relief valve is fitted upstream of the non-return valve to safeguardthe pump against excessive pressures.

Exercise

Positional sketch


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A-17Exercise 4

EXERCISE SHEET

Circuit diagram, hydraulic


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A-18Exercise 4

Item no. Qty. Description

What is the disadvantage of this circuit?

Components list

Conclusion


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A-19Exercise 5

Hydraulics

Hardening furnace

T To familiarise the student with the applications of a 3/2-way valve

T To show how to determine times, pressures and forces during theadvance and return strokes of a single-acting cylinder


T Determining the necessary components


T Measuring the travel pressure and travel time for the advance andreturn strokes

T Calculating the required advance-stroke pressure

T Calculating the advance-stroke speed and time

Subject

Title

Training aim

Problem definition


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A-20Exercise 5

The cover of a hardening furnace is to be raised by a single-acting cyl-inder. The cylinder is activated by a 3/2-way valve. A 9 kg weight is at-tached to the cylinder to represent the load. Measure and calculate thefollowing values:

T Travel pressure, load pressure, resistances and back pressure

T Advance-stroke time and speed

Exercise

Positional sketch


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A-21Exercise 5

EXERCISE SHEET

Direction Travel pressure Travel time

Advance stroke

Return stroke

Characteristic data required for calculation:

Applied load: FG = 90 N

Piston area: APN = 2 cm2

Stroke length: s = 200 mm

Pump output: q = 2 l/min

Load pressure: pF

AL

G

PN

=

pL =

pressureload-pressureTravel=resistanceHydraulic

pres =

How great is the back pressure in relation to the hydraulic resistance?

Evaluation

Conclusion


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A-22Exercise 5

Advance-stroke speed: vq

Aadv

PN

=

vadv =

Advance-stroke time: ts

vadv

adv

=

tadv =

Do the calculated and measured advance-stroke times agree?

Conclusion


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A-23Exercise 6

Hydraulics

Furnace door control


T To show how to determine times, pressures and forces during theadvance and return strokes of a double-acting cylinder



T Practical assembly of circuit

T Measuring the travel and back pressures and transfer time for theadvance and return strokes

T Calculation of advance and return-stroke speeds

T Comparison of calculated and measured values

Subject

Title

Training aim

Problem definition


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A-24Exercise 6

A furnace door is opened and closed by a double-acting cylinder. Thecylinder is activated by a 4/2-way valve with spring return. This ensuresthat the door opens only as long as the valve is actuated. When thevalve actuating lever is released, the door closes again.

Exercise

Positional sketch


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A-25Exercise 6

EXERCISE SHEET



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A-26Exercise 6

Advance stroke Travel pressure p1S1

Back pressurep1S2

Travel timetadv

Return stroke Back pressure p1S1

Travel pressurep1S2

Travel timetret


Piston area: APN = 2.0 cm2

Piston annular area: APR = 1.2 cm2



Area ratio:PR

PN

A

A=

=

Advance-stroke speed.:PN

advA

qv =

=advV


vadv

adv

=

=advt

Return-stroke speed:PR

retA

qv =

=retV

Evaluation


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A-27Exercise 6

Return-stroke time:ret

retv

st =

=rett

Ratio of travel speeds:

=

ret

adv

V

V

Ratio of travel times:

=

ret

adv

t

t

Compare the advance- and return-stroke speeds and times with the

area ratio. What is the relationship between these?

Conclusion


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A-28Exercise 6


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A-29Exercise 7

Hydraulics

Conveyor tensioning device


T To show how to use a piloted non-return valve




T Measuring travel and back pressure and the system pressure in allvalve positions

T Calculating the power balance for circuits with various 4/3-way valveswith different mid-positions

Subject

Title

Training aim

Problem definition


56/204


A-30Exercise 7

Parts are fed through a drying oven on a steel chain conveyor belt. Itmust be possible to correct the tracking of the belt by means of a ten-sioning device to ensure that the belt does not run off its rollers. Thisdevice consists of a steel roller fixed at one end and movable at theother by means of a double-acting cylinder. Hydraulic power must beavailable continuously. The hydraulic system must switch to the recircu-lating (pump bypass) condition when the directional control valve is notactuated. The clamping station causes a continuous counter force to acton the cylinder. A piloted non-return valve is used to prevent creepageof the piston rod of the positioning cylinder as a result of oil leakagelosses in the directional control valve.

For the purposes of comparison, calculate the required drive power forcircuits firstly with a 4/3-way valve, recirculating in mid-position and sec-ondly with a 4/3-way valve, closed in mid-position.

Exercise

Positional sketch


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A-31Exercise 7

EXERCISE SHEET



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A-32Exercise 7

Direction Valve position System pressure

Travel and back pressure

p0Z2 p1S1 p1S2

Advance stroke

Return stroke

Mid-position

Calculation of drive power:: Pp q

DR =


PDR = Required drive power

p = System pressure supplied by pump: Maximum 50 bar

q = Flow rate of pump: Constant 2 l/min

= Pump efficiency: Approx. 0.7

Drive power with closed mid-position:

PDR =

Drive power with recirculating mid-position:

PDR =

What is the advantage of a recirculating (bypass) circuit?

Evaluation

Conclusion


59/204


A-33Exercise 8

Hydraulics

Cold-store door

T To show the use of a hydraulic accumulator as a power source

T To show how to use the accumulator to power advance and returnstrokes of the cylinder after the pump is switched off




T Determining the number of working cycles possible after the pump isswitched off


T Explaining the design and mode of operation of a diaphragm accumu-lator

T Naming possible applications of an accumulator

Subject

Title

Training aim

Problem definition


60/204


A-34Exercise 8

A heavy cold-store door is opened and closed by a hydraulic cylinder. Ahydraulic accumulator is to be installed to allow the door to be closed inthe case of an electrical power failure. This will permit the cold-storedoor to be opened and closed a number of times. A 4/2-way valve is tobe used to activate the cylinder. This valve should be connected up insuch a way that the piston rod is advanced with the valve in its normalposition.

No provision will be made here for the safety cut-out which is essentialto prevent persons from becoming trapped in the door. This cut-outfunction is normally provided by an electrical control device for the hy-

draulic system.

Be sure to follow the operating instructions for the accumulator. Afterswitching off the control system, do not dismantle the hydraulic compo-nents until you have relieved the pressure in the accumulator and iso-lated this from the control system by means of the built-in shut-off valve.

It is essential to relieve the accumulator pressure via a flow controlvalve!

Exercise

Positional sketch


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A-35Exercise 8

EXERCISE SHEET



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A-36Exercise 8

System pressure Opening Closing

20 bar

50 bar

What is the effect of fitting an accumulator to this circuit?

Explain the design and function of a diaphragm accumulator.

Name examples of applications of accumulators.

Evaluation

Conclusion


63/204


A-37Exercise 9

Hydraulics

Rotary machining station

T To familiarise the student with the use of a 2-way flow control valve

T To show how to assemble a counter-holding circuit

T Understanding of a hydraulic circuit diagram


T Commissioning a circuit with a flow control valve and counter-holding

T Adjustment and measurement of inlet and outlet pressures and cylin-der travel time

T Comparison of cylinder advance-stroke times for various inlet andoutlet pressures

Subject

Title

Training aim

Problem definition


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A-38Exercise 9

Several stations on a rotary machining station are driven by a hydraulicpower pack.

As individual stations are switched on and off, they produce pressurefluctuations throughout the hydraulic circuit. This effect will be studiedon a drilling station. The fluctuations in pressure and the tractive forcescreated during drilling must not affect the feed of the drilling station. Aflow control valve is to be used to ensure a smooth adjustable feed rate,while a pressure relief valve is to be used as a counter-holding valve tocompensate for the tractive forces.

Exercise

Positional sketch


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A-39Exercise 9

EXERCISE SHEET



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A-40Exercise 9

Measure the following:

p1Z1 = Pressure upstream of flow control valve

p1Z3 = Pressure downstream of flow control valve

p1Z4 = Pressure at counter-holding valve

t = Advance-stroke time of cylinder

p1Z1 p1Z3 p1Z4 t

50 bar 10 bar

40 bar 10 bar

30 bar 10 bar

20 bar 10 bar

10 bar 10 bar

p1Z1 p1Z3 p1Z4 t

50 bar 10 bar

50 bar 20 bar

50 bar 30 bar

50 bar 40 bar

50 bar 50 bar

How does the travel change as the pressures at the inlet and outletvary?

Evaluation

Fluctuatinginlet pressure

Fluctuatingoutlet pressure

Conclusion


67/204


A-41Exercise 10

Hydraulics

Painting booth

T To show how to plot a characteristic for a 2-way flow control valve

T To show how to make a comparison between a 2-way flow controlvalve and a throttle-type flow control valve



T Measurement of pressure and flow rate

T Plotting the characteristic of the 2-way flow control valve

T Comparison with a throttle valve

Subject

Title

Training aim

Problem definition


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A-42Exercise 10

An endless chain conveyor feeds workpieces through a painting booth.The chain is driven by a hydraulic motor via a right-angle gear unit. Dueto changes in the production process, the weight of the workpiecespassing through the painting booth has changed. The speed of the con-veyor should, however, remain the same as before. It must be deter-mined whether this can be achieved by fitting a flow control valve, and ifso which type is suitable.

Exercise

Positional sketch


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A-43Exercise 10

EXERCISE SHEET


p1Z1 = Pressure upstream of valve

p1Z2 = Pressure downstream of valve

qTWFCV = Flow rate through 2-way flow control valve

qTV = Flow rate through throttle valve

p1Z1 p1Z2 qSRV qDV

50 bar 10 bar 2 l/min 2 l/min

50 bar 20 bar

50 bar 30 bar

50 bar 40 bar

50 bar 50 bar

p1Z1 p1Z2 qSRV qDV

50 bar 10 bar 2 l/min 2 l/min

40 bar 10 bar

30 bar 10 bar

20 bar 10 bar

10 bar 10 bar

Evaluation

Fluctuatingload pressure



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A-44Exercise 10

Which valve is suitable for this application and why?

Flow control valvecharacteristic

Conclusion


71/204


A-45Exercise 11

Hydraulics

Embossing machine

T To familiarise the student with the use of a one-way flow control valve

T To show how to explain the difference between a flow control valveand throttle valve on the basis of a concrete application



T Commissioning a circuit with a one-way flow control valve andcounter-holding

T Adjustment and measurement of inlet and outlet pressures and cylin-der advance-stroke time

T Comparison of advance-stroke times with those in exercise 9

Subject

Title

Training aim

Problem definition


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A-46Exercise 11

A special machine is used to emboss graphic symbols on metal foil. Thefoil is fed through the embossing machine with an adjustable cycle time.The downward motion of the stamp must be capable of being varied inaccordance with the feed speed. The return motion must always beexecuted as a rapid traverse.

A one-way flow control valve is used to control the speed of the stamp,while a pressure relief valve is used to prevent the weight of the stampfrom pulling the piston rod out of the cylinder. A 4/2-way valve is used toswitch between upwards and downwards motion.

Exercise

Positional sketch


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A-47Exercise 11

EXERCISE SHEET



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A-48Exercise 11


p1Z1 = Pressure upstream of one-way flow control valve

p1Z3 = Pressure downstream of one-way flow control valve

p1Z4 = Pressure at counter-holding valve

t = Cylinder advance-stroke time

p1Z1 p1Z3 p1Z4 t

50 bar 10 bar

40 bar 10 bar

30 bar 10 bar

20 bar 10 bar

10 bar 10 bar

p1Z1 p1Z3 p1Z4 t

50 bar 10 bar

50 bar 20 bar

50 bar 30 bar

50 bar 40 bar

50 bar 50 bar

How does the travel time change as the pressures at the inlet and outletvary?

What is the difference between this circuit and the one with the 2-wayflow control valve (see exercise 9) and what is the reason for this?

Evaluation


Fluctuatingoutlet pressure

Conclusion


75/204


A-49Exercise 12

Hydraulics

Surface grinding machine

T To familiarise the student with the design and mode of operation of adifferential circuit

T To show how to explain the influence of pressures, forces, speedsand travel times

T Understanding a hydraulic circuit diagram


T Measuring advance and return stroke times and travel and backpressures

T Calculation of ratios for area and force

T Calculation of the flow rate through the flow control valve

T Comparison of this circuit with the one in exercise 6

Subject

Title

Training aim

Problem definition


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A-50Exercise 12

The grinding table of a surface grinding machine is driven by a hydrauliccylinder. Since the speed is required to be the same in both directions,the hydraulic control circuit must be designed to provide compensationfor the difference in volume of the two cylinder chambers. A differentialcircuit is suggested with a 3/2-way valve and a flow control valve forspeed adjustment.

Exercise

Positional sketch


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A-51Exercise 12

EXERCISE SHEET



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A-52Exercise 12


p1Z1 = Pressure on piston side of cylinder

p1Z2 = Pressure on annular side of cylinder

p0Z2 = System pressure = 50 bar

t = Cylinder advance-stroke time approx. 4 s

Direction p 1Z1 p1Z2 t

Advance stroke

Return stroke

Cylinder dimensions:



Cylinder stroke: s = 0.2 m

Area ratio: ==PR

PNA

A

Time ratio: =ret

adv

t

t

Force ratio: =

=

2Z1PR

1Z1PN

2

1

pA

pA

F

F

Flow rate during advance stroke:

Piston side: ==adv

PNPNt

sAq

Piston annular side: ==adv

PRPRt

sAq

Evaluation

Values table


79/204


A-53Exercise 12

EXERCISE SHEET

Flow control valve component:

== PRPNFCV qqq

Flow rate during return stroke:

Piston annular side: ==ret

PRPRtsAq

When the 3/2-way valve is activated, the same pressure is present atboth cylinder ports. Why does the piston advance?

During the advance stroke, the pressures in the two cylinder chambersare different. Why does the piston advance despite the fact that thetravel pressure is lower than the back pressure?

What force can the cylinder exert during its advance stroke?

Conclusion


80/204


A-54Exercise 12

What is the difference between this differential circuit and a simple cyl-inder control circuit (one connection to each of P and T as, for example,in exercise 6)?

1. What are the factors governing the advance-stroke speed vadv?

2. What is the value of the return-stroke speed vret in comparison withthe advance-stroke speed vadv?

3. What are the factors governing the advance-stroke time tadv?

4. What is the value of the return-stroke time t ret in comparison with theadvance-stroke time tadv?

System Simple cylinder control circuit Differential circuit

1. Advance-stroke speedvadv

2. Return-stroke speed vret

3. Advance-stroke timetadv

4. Return-stroke time

tret

What area ratio results in identical advance and return stroke speeds(using a differential circuit)?

Vergleich

Conclusion


81/204


A-55Exercise 13

Hydraulics

Drilling machine

T To teach the student how to design a control circuit with reduced out-put pressure

T To show how to explain the mode of operation of a 3-way pressureregulator



T Measuring the travel and back pressures

T Setting a counter pressure

T Assessment of the effect of using a pressure regulator

Subject

Title

Training aim

Problem definition


82/204


A-56Exercise 13

A drilling machine is used for work on various hollow workpieces. Theworkpieces are hydraulically clamped in a vice. It must be possible toreduce the clamping pressure to suit the design of the workpiece. Itmust also be possible to vary the closing speed by means of a one-wayflow control valve.

Exercise

Positional sketch

1A


83/204


A-57Exercise 13

EXERCISE SHEET


p1Z1 = Pressure upstream of flow control valve

p1Z2 = Pressure upstream of cylinder

p1Z3 = Pressure downstream of cylinder

Study the following cases:

1. Piston advance stroke

2. Piston advanced to end position with setting p1Z2 = 15 bar.

3. Piston advance stroke with counter pressure setting, p1Z3 = 20 bar.

4. Piston advanced to end position

5. Piston advance stroke with shut-off valve closed

6. Piston advanced to end position with shut-off valve closed

Cases of examination p 1Z1 p1Z2 p1Z3

1. Advance stroke

2. End position

3. Advance stroke with counter pressure

4. End position

5. Advance stroke with pressure regulator

6. End position

Cases of examination p 1Z1 p1Z2 p1Z3

1. Return stroke

2. End position

3. Return stroke with counter pressure

4. End position

5. Return stroke with pressure regulator

6. End position

Evaluation

Advance stroke

Return stroke


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A-58Exercise 13

When is it appropriate to use a pressure regulator?

What possible disadvantage may result from the use of a pressureregulator?

Conclusion


85/204


A-59Exercise 14

Hydraulics

Bulkhead door

T To familiarise the student with a circuit for the hydraulic clamping of abulkhead door

T To demonstrate a comparison of circuits with and without counter-holding



T Measuring the cylinder advance-stroke time with and without a loadand with and without counter-holding

T Comparison and assessment of results

Subject

Title

Training aim

Problem definition


86/204


A-60Exercise 14

A double-acting cylinder is used to open and close a bulkhead door.Closing must be carried out smoothly and at a constant adjustablespeed. The speed is adjusted by means of a one-way flow control valve.A pressure relief valve must be fitted to provide counter-holding andprevent the heavy door from pulling the piston rod out of the cylinderduring the closing operation.

Exercise

Positional sketch


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A-61Exercise 14

EXERCISE SHEET



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A-62Exercise 14



p1Z1 = Cylinder travel pressure

p1Z2 = Cylinder back pressure

p0Z2 = System pressure

The applied load and counter-holding should now be varied. Initial set-tings should be such as to achieve an advance-stroke time of 5 s with asystem pressure of 50 bar but without an applied load or counterholding.

10 bar back pressure should subsequently be set.

When dismantling the circuit, ensure that no pressurised fluid is trapped(p1Z2= 0 bar).

Load and counter-holding p 0Z2 p1Z1 p1Z2 t

Without load or counter-holding 50 bar 5 s

With load without counter-holding

With load and counter-holding10 bar

Without load with counter-holding 10 bar

How does the travel time vary as the load changes?

Which circuit is more suitable?

Evaluation

Values table

Conclusion


89/204


A-63Exercise 15

Hydraulics

Ferry loading ramp

T To familiarise the student with a speed control circuit with a tractiveload

T To compare circuits with flow control valves in the inlet line and outletline respectively



T Measuring the cylinder advance time and travel and back pressureswith flow control valves in the inlet line and outlet line respectively

T Comparison and assessment of results

Subject

Title

Training aim

Problem definition


90/204


A-64Exercise 15

The loading ramp of a car ferry must be capable of being set to differentheights. The ramp is raised and lowered by a hydraulic cylinder. Thismotion must be carried out smoothly and at a constant speed. A flowcontrol valve is to be used to adjust the speed. This must be installed insuch a way as to prevent excessive pressures from developing withinthe system.

Exercise

Positional sketch


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A-65Exercise 15

EXERCISE SHEET



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A-66Exercise 15



p1Z1 = Cylinder travel pressure

p1Z2 = Cylinder back pressure

p0Z2 = System pressure

Vary the following:

T

Applied loadT Counter-holding

T Flow control in inlet and outlet lines

Settings:

T First, without an applied load or counter-holding and with a flow con-trol valve in the inlet line, make settings to obtain an advance-stroketime of t > = 5 s with a system pressure of p0Z2 = 50 bar.

T Then set a counter pressure of p1Z2 = 10 bar.

T Then use a flow control valve in the outlet line to provide counter-holding.

When dismantling the circuit, ensure that no pressurised fluid is trapped(p1Z2= 0 bar).

Evaluation


93/204


A-67Exercise 15

EXERCISE SHEET

Load and counter-holding p 0Z2 p1Z1 p1Z2 t

Without load or counter-holding 50 bar 5 s

With load without counter-holding

With load and counter-holding 10 bar

Without load with counter-holding 10 bar

Load p 0Z2 p1Z1 p1Z2 t

Without load 50 bar 5 s

With load

How does the travel time change as the load is varied?

Which circuit is more suitable?

Flow control valvein inlet line

Flow control valvein outlet line

Conclusion


94/204


A-68Exercise 15


95/204


A-69Exercise 16

Hydraulics

Skip handling

T To develop a hydraulic circuit for a double-acting cylinder subject to avarying load

T Drawing the circuit diagram


T Commissioning of control circuit

T Description of mode of operation of control circuit

Subject

Title

Training aim

Problem definition


96/204


A-70Exercise 16

The loading and unloading of skips from a skip transporter is carried outusing two double-acting cylinders. Each cylinder is subject to varyingloads tractive load during unloading and compressive load duringloading. The skip should be raised and lowered at a slow constantspeed. Each cylinder must therefore be hydraulically clamped on bothsides.

Exercise

Positional sketch


97/204


A-71Exercise 16

EXERCISE SHEET



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A-72Exercise 16

How is hydraulic clamping produced on both sides?

Conclusion


99/204


A-73Exercise 17

Hydraulics

Bonding press

T To teach the student how to specify the pressure for a double-actingcylinder

T

To show how to choose either a pressure relief valve or a pressureregulator



T Measurement and comparison of system pressure, travel pressureand final pressure

T Assessment of the suitability of a pressure relief valve and pressureregulator

Subject

Title

Training aim

Problem definition


100/204


A-74Exercise 17

A bonding press is used to stick pictures or lettering onto wood or plasticpanels. The working pressure must be adjustable to suit the base mate-rial and adhesive used and must be capable of being maintained for along time while the directional control valve is activated.

Develop and compare two circuits. The first should use a 3-way pres-sure regulator to adjust the press pressure, while the second shouldincorporate a pressure relief valve connected into the bypass line for thispurpose. A 4/3-way valve should be used for activation in both cases.

Exercise

Positional sketch


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A-75Exercise 17

EXERCISE SHEET



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A-76Exercise 17

Carry out the following settings:

p0Z2 = System pressure = 50 bar

p1Z2 = Pressure upstream of cylinder = 30 bar

With which circuit does the system pressure vary as the cylinder ad-vances?

When is it advantageous to use the pressure relief valve?

Evaluation

Conclusion


103/204


A-77Exercise 18

Hydraulics

Assembly device

T To familiarise the student with a pressure sequence circuit

T To teach the student how to draw a displacement-step diagram

T Development of hydraulic circuit diagram

T Drawing the displacement-step diagram


T Systematic commissioning with setting of pressure and flow rate

Subject

Title

Training aim

Problem definition


104/204


A-78Exercise 18

An assembly device is used to press workpieces together for drilling.Cylinder 1A1 presses a workpiece into the housing. This operationshould be carried out slowly at a constant speed. When the pressure incylinder 1A1 has reached 20 bar (workpiece pressed into place), a holeis drilled through the workpiece and housing. The drill is driven by a hy-draulic motor. After the drilling operation, the drill is switched off andretracted (1A2). Cylinder 1A1 is retracted only when the drill has with-drawn from the housing.

Exercise

Positional sketch

1A2

1A1


105/204


A-79Exercise 18

EXERCISE SHEET



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A-80Exercise 18

What are the points to note when commissioning the control circuit?

1.

2.

3.

4.

5.

6.

Displacement-step diagram

Conclusion

Designation

SignalDescription

Step

TimeComponents


107/204


A-81Exercise 19

Hydraulics

Calculations for an assembly device

T To enable the student to calculate the forces associated witha dou-ble-acting cylinder

T To enable the student to calculate the advance-stroke time of a cylin-der piston

T Writing a problem description

T Calculating the press-fitting force

T Calculating the press-fitting time

Subject

Title

Training aim

Problem definition


108/204


A-82Exercise 19

An assembly device is used to press workpieces together for drilling.The operating sequence is described in exercise 18. Our objective hereis to check the pressing operation of cylinder 1A1 mathematically. De-termine the press-fitting force using the given data. Note that, while thepress-fitting pressure is available as specified, the resistances of thelines and directional control valve cause an opposing pressure to act onthe annular piston side, thus reducing the actual force available.The flowrate is kept constant by a flow control valve. This together with the cylin-der stroke is used to calculate the travel time for the press-fitting opera-tion.

Exercise

Positional sketch

1A1


109/204


A-83Exercise 19

EXERCISE SHEET

Characteristic data of control system:

Cylinder:

Piston diameter D = 50 mm

Piston rod diamete d = 25 mm

Stroke s = 250 mm

Hydraulic system:

Flow rate q = 5 l/min

Press-fitting pressure p1 = 50 bar

Counter pressure p2 = 6 bar

Evaluation

Schematic diagram


110/204


A-84Exercise 19

Piston force:

== 1PN1 pAF

Counter force:

== 2PR2 pAF

Press-fitting force:

F F F= =1 2

Press-fitting time:

tV

q= =


111/204


A-85Exercise 20

Hydraulics

Tipping container

T To familiarise the student with an electrohydraulic circuit

T Development of hydraulic and electrical circuit diagrams

T Assembly of control system

Subject

Title

Training aim

Problem definition


112/204


A-86Exercise 20

A conveyor belt transports metal swarf into a tipping container. Whenthe container is full, it is emptied into a truck. A double-acting cylinder isused for this purpose, activated by a solenoid-actuated 4/3-way valve.The piston rod of the cylinder is advanced while the container is in posi-tion to receive swarf. To enable the hydraulic power pack to be switchedoff during this time, the piston rod of the cylinder must be protected byhydraulic means against undesired retraction (caused by leakage in thevalve). The electrical activation of the valve must be manually controlled,i.e. the cylinder must move only when the Up or Down pushbuttonsare pressed.

Exercise

Positional sketch


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A-87Exercise 20

EXERCISE SHEET



114/204


A-88Exercise 20

What measure ensures that the cylinder maintains its position and doesnot move even if the Up and Down pushbuttons are accidentally

pressed simultaneously?

Circuit diagram,electrical

Conclusion

S1 = Up pushbuttonS2 = Down pushbutton


115/204


B-1Fundamentals

Section B Fundamentals

The theoretical fundamentals for the Hydraulics training package aresummarised in the textbook:

Hydraulics

Basic Level TP501


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B-2Fundamentals


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C-1

Section C Solutions

Solution 1: Automatic lathe C-3

Solution 2: Package lifting device C-7

Solution 3: Drawing press C-11

Solution 4: Calender feeding device C-15

Solution 5: Hardening furnace C-19

Solution 6: Furnace door control C-23

Solution 7: Conveyor tensioning device C-27

Solution 8: Cold-store door C-33

Solution 9: Rotary machining station C-37

Solution 10: Painting booth C-41

Solution 11: Embossing machine C-45

Solution 12: Surface grinding machine C-49

Solution 13: Drilling machine C-59

Solution 14: Bulkhead door C-65

Solution 15: Ferry loading ramp C-69

Solution 16: Skip handling C-73

Solution 17: Bonding press C-77

Solution 18: Assembly device C-79

Solution 19: Calculation for an assembly device C-83

Solution 20: Tipping container C-85


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C-2


119/204


C-3Solution 1

Automatic lathe


Practical assembly,hydraulic


120/204


C-4Solution 1


0Z1 1 Hydraulic power pack

0Z2 1 Pressure gauge

1V 1 Shut-off valve

1S 1 Flow sensor

3 Hose line

Once the hydraulic circuit has been assembled, valve 1V should be fully

opened. Now close this valve slowly to set the first p value as shown onthe pressure gauge 0Z2. The maximum attainable pressure is 60 bar,governed by a pressure relief valve built into the pump which is set tothis value.

System pressure p 15 20 25 30 35 40 45 50 bar

Flow rate q 2.33 2.31 2.29 2.28 2.26 2.24 2.22 2.20 l/min

Components list


Evaluation

Pump characteristic


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C-5Solution 1

As the pressure rises, the pump delivery falls slightly. In theory, thecharacteristic curve for the pump should be a straight line.The decreasein pump delivery is due to internal leakage losses, which becomegreater as the pressure increases The ratio of the measured pump de-livery and theoretical pump delivery is the effective volumetric efficiencyof the pump.

For technical reasons, the actual value recorded in this exercise is thepower consumption of the electric motor or the premature opening of thepressure relief valve. The pump is dimensioned for a maximum pressureof 250 bar (see data sheet). An electric motor with an appropriately highrating would be required to achieve this. This would not, however, bemeaningful, since the exercises are carried out with a maximum pres-sure of 60 bar.

Conclusions


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C-6Solution 1


123/204


C-7Solution 2

Package lifting device



124/204


C-8Solution 2




1V1 1 Shut-off valve

1V2 1 Pressure relief valve

1S 1 Flow sensor

5 Hose line

2 Branch tee


Components list

Measuredvalue

q inl/min

Pump safety valvepmax = 60 bar (6 MPa)

System pressurep = 50 bar (5 MPa)(Shut-off valve 1V1closed)


125/204


C-9Solution 2

Once the hydraulic circuit has been assembled and checked, valve 1V1should be closed and the pressure relief valve 1V2 fully opened. Switchon the hydraulic power pack and close the pressure relief valve until thepressure gauge 0Z2 indicates 50 bar. Now fully open shut-off valve 1V1and close it again in steps to set the pressures specified in the table;evaluate the associated flow rates. At the same time, observe the pres-sure at which the valve begins to open.

If, at 50 bar pressure, a flow rate of 2.3 l/min is not measured at thepressure relief valve, this indicates that the pressure relief valve fitteddirectly to the pump is already starting to open.

Working pressure p 35 40 42.5 45 47.5 50 bar

Flow rate q 0 0 0 0.2 1.17 2.15 l/min


Remark

Evaluation

Pressure reliefvalve characteristic

Opening pressure

Maximum pressure


126/204


C-10Solution 2

Every pressure relief valve has a certain opening pressure at whichpoint diversion of the flow through the valve begins. The difference be-tween opening pressure and maximum pressure is 5 bar in this case.When the preset maximum pressure is reached, the entire pump deliv-ery is discharged via the pressure relief valve.

A piloted pressure relief valve can also be used to record the character-istic. Due to the low flow rate, the same shape of characteristic curvewill be obtained.

Conclusions


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C-11Solution 3

Drawing press



128/204


C-12Solution 3


System pressurep = 50 bar (5 MPa)


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C-13Solution 3



0Z2, 0Z3, 0Z4 3 Pressure gauge


0V2 1 Flow control valve



1V3 1 Throttle valve

1V2 1 4/2-way valve

1V1 1 4/3-way valve

1S 1 Flow sensor

7 Hose line

3 Branch tee

Once the hydraulic circuit has been assembled and checked, the shut-off valve 0V3 should be closed and the pressure relief valve 0V1 fullyopened. Switch on the hydraulic power pack and close the pressurerelief valve until the pressure gauge 0V1 indicates 50 bar. Now carry outthe series of measurements specified in the table. Adjust the flow rateby means of the flow control valve 0V2 and measure it with the flowsensor 1S.

Pressure sensors are recommended for the measurement of pressuresat items 0Z3 and 0Z4.

Components list



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C-14Solution 3

p0Z3 = Pressure upstream of component

p0Z4 = Pressure downstream of component

Component Flow rate q

l/min

Pressurep0Z3bar

Pressurep0Z4bar

Pressure difference

pbar

Pressure reliefvalve,fully open

2

1

4.6

1.9

2.5

1.0

2.1

0.9

Throttle valve,fully open

2

1

4.3

1.9

2.5

1.2

1.8

0.7

4/2-way valve,P > A

2

1

4.0

1.9

2.5

1.2

1.5

0.7

4/3-way valve,P > A

2

1

4.3

1.8

2.5

1.1

1.8

0.7

When the flow rate doubles, the pressure difference increases by evenmore than this. The hydraulic resistance increases. This pressure lossmeans a loss of power.

Evaluation

Values table

Conclusions


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C-15Solution 4

Calender feeding device



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C-16Solution 4


Pump safety valvepmax = 60 bar (6 MPa)

Systempressurep = 50 bar(5 MPa)


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C-17Solution 4



0V1 1 Non-return valve (5 bar)



1V 1 Shut-off valve

1A 1 Cylinder, double-acting

1Z 1 Loading weight

8 Hose line

4 Branch tee

For this exercise, the cylinder is bolted onto the base plate on the left ofthe profile plate and loaded with the weight. When the cylinder is con-nected up, it is essential that the upper connection is connected to thetank. Once the circuit has been assembled, the PRV 0V2 should first befully opened. The hydraulic power pack should then be switched on andthe PRV 0V2 slowly closed. The piston rod will then travel to its upperend position. Continue to close the PRV until the pressure gauge 0Z2

indicates 50bar. Now switch off the hydraulic power pack. It can bedemonstrated by briefly opening the shut-off valve that the non-returnvalve prevents the weight from lowering further and that return flow ofhydraulic fluid during the return stroke can take place only via the 2/2-way valve 1V.

The piston rod can retract only when the pump is switched off. This isarranged intentionally in systems like the one shown here. This ensuresthat the hydraulic power pack is switched off during lengthy standstillperiods.

Components list


Conclusions


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C-18Solution 4


135/204


C-19Solution 5

Hardening furnace



136/204


C-20Solution 5


Pumpsafety valve

pmax = 60 bar(6 MPa)



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C-21Solution 5



0Z2, 0Z3, 1Z1 3 Pressure gauge

0V1 1 Non-return valve


1V 1 4/2-way valve, manually operated

1A 1 Cylinder, double-acting

1Z2 1 Loading weight

7 Hose line

3 Branch tee

1 Stop-watch

For this exercise, the cylinder is bolted onto the base plate on the left ofthe profile plate and loaded with the weight. When the cylinder is con-nected up, it is essential that the upper connection is connected to thetank. In place of a 3/2-way valve, a 4/2-way valve is now used, with oneconnection blanked off. Once the circuit has been assembled, the PRV0V2 should first be fully opened. The hydraulic power pack should then

be switched on and the PRV 0V2 slowly closed until the pressure gauge0Z3 indicates 50 bar. The 4/2-way valve 1V can now be slowly reversed,which will cause the piston rod of the cylinder to advance. The design ofthe valve means that, as this is slowly reversed, the full cross-section ofthe valve is not immediately opened. Initially, the pump delivery to thecylinder will be throttled. As soon as the valve is returned to its initialposition, the piston rod of the cylinder will return to its lower end posi-tion.

The values specified in the tables can now be measured.

Direction Travel pressure Travel time

Advance stroke 8 bar 1.1 s

Return stroke 0 bar 1.4 s

Components list


Evaluation


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C-22Solution 5


Applied load:: FW = 90 N

Piston area: APN = 2 cm2


Pump delivery: q = 2 l/min

Load pressure: pF

A

N

cm

N

cm

barLW

PN

= = = =90

2

454 5

2 2.

Hydraulic resistance = Travel pressure - load pressure

pres = 8 bar - 4.5 bar = 3.5 bar

The back pressure is considerably lower than the hydraulic resistance. Acylinder motion can take place only if this case applies. The value of theback pressure depends on the hydraulic resistances. These are very lowwhen fluid is discharged into the tank.


A

l

cm

cm

s

cmadv

PN

= = =

2

2

2000

60

22

3

2

min

vcm

s

m

sadv = =16 67 017. .


v

m

m

s

sadvadv

= = =0 2

01712

.

..

The measured advance-stroke time, 1.1 s., is slightly less than the cal-culated time. The reason for this may be that the delivery of a new pumpis somewhat greater than 2 l/min.

Conclusions

Conclusions


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C-23Solution 6

Furnace door control



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C-24Solution 6



0Z2 1 Pressure gauge1S1, 1S2 2 Pressure sensor

0V 1 Pressure relief valve

1V 1 4/2-way valve, manually operated

1A 1 Cylinder

6 Hose line

2 Branch tee

1 Stop-watch


Components list

Pumpsafety valve




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C-25Solution 6

Once the circuit has been assembled and checked, the hydraulic powerpack should be switched on and the system pressure set on the pres-sure relief valve 0V to 50 bar. Pressure sensors should be used tomeasure the travel and back pressures. Pressure gauges are sluggishin operation and would give incorrect readings.

When the hand lever of the 4/2-way valve is actuated, the piston rod ofthe cylinder will advance until the lever is released or the piston rod runsagainst the stop. When the lever is released, the piston rod will imme-diately return to its retracted end position. Before the pressures andtimes are measured, the piston rod should be advanced and retracted

several times to expel any air which may have entered the piston-rodchamber during the previous exercises.

Advance stroke Travel pressure p1S1

Back pressurep1S2

Travel timetadv

2.4 bar 2 bar 1.2 s

Return stroke Back pressure p1S1

Travel pressurep1S2

Travel timetein

5.3 bar 11 bar 0.8 s






Area ratio: = = =A

A

cm

cm

PN

PR

2

12 1667

2

2. .


A

l

cm

cm

s

cmadv

PN

= = =

2

2

2000

60

22

3

2

min

Vcm

s

m

sadv = =16 67 017. .


Evaluation


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C-26Solution 6


v

m

m

s

sadvadv

= = =2

017

12

.

.

Return-stroke speed: vq

A

l

cm

cm

s

cmret

PR

= = =

2

12

2000

60

122

3

2

min

. .

v cms

ms

ret = =27 78 0 28. .

Return-stroke time: ts

v

m

m

s

sretret

= = =0 2

0 28

0 7.

.

.

Travel speed ratio:V

V

m

s

ms

adv

ret

= =

017

0 28

0 6

.

.

.

Travel time ratio:t

t

s

s

adv

ret

= =12

0 717

.

..

The travel speed ratio is equal to the area ratio of the cylinder. Thespeed ratio is equal to the reciprocal of the area ratio.

Conclusions


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C-27Solution 7

Conveyor tensioning device



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C-28Solution 7


Pump safetyvalve




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C-29Solution 7




1S1, 1S2 2 Pressure sensor



1V1 1 4/3-way valve, manually operated, Recirculating mid-position

1V2 1 Pilot-operated non-return valve

1A 1 Cylinder

9 Hose line

3 Branch tee

1 Stop-watch

After the circuit has been assembled and tested, the shut-off valve 0V2should be closed and the pressure relief valve 0V1 opened. Switch onthe hydraulic power pack and close the PRV 0V1 until the pressuregauge 0Z1 indicates 50 bar.

The shut-off valve 0V2 can now be opened. Observe when doing thisthat the pressure gauge 0Z1 shows an immediate drop from the setpressure of 50 bar to approx. 3 bar, since in its mid-position the 4/3-wayvalve 1V1 discharges the flow of hydraulic fluid to the tank. The pistonrod can be brought into any desired position by actuating the 4/3-wayvalve. When this valve is brought into its mid-position, the piston rodimmediately halts.

The non-return valve prevents the piston rod from being pushed back bya counter force.

Components list



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C-30Solution 7

In conjunction with the pilot-operated non-return valve, a 4/3-way valvewith a mid-positi

Documents

Hydraulics Workbook