Pneumatic Circuit Design

Pneumatic Circuit Design

Uma Devi Nadarajah

Pneumatic Circuit Design

by

Uma Devi Nadarajah

Mechanical Engineering Department
Politeknik Banting Selangor

https://pbs.mypolycc.edu.my
1st Edition 2022

Uma Devi Nadarajah

PNEUMATIC CIRCUIT DESIGN

Declaration
Pneumatic Circuit Design
All right reserved. No part of this publication may be reproduced
or transmitted in any form or by any electronic or mechanical
including photocopy, recording, or any information storage and
retrieval system without permission from Politeknik
Banting Selangor and Bahagian Instruksional dan Pembelajaran

Digital JPPKK.

Author
Uma Devi Nadarajah

Editor
Zalaida Binti Talib
1st Published 2022

Published by:
Politeknik Banting Selangor,
Persiaran Ilmu, Jalan Sultan Abdul Samad,
42700 Banting, Selangor Darul Ehsan.
Telephone : 03-3120 1657 / 03-3120 1625

Fax: 03-3120 1706
Website : https://pbs.mypolycc.edu.my/

E-mel : [email protected]

i

ACKNOWLEDGEMENT

We would like to thank Politeknik Banting Selangor for providing us with
the wonderful opportunity to write this e-book. We would like to thank
everyone who gave us the opportunity to discover the hidden talent
within us to become authors, which may have been hidden deep within
us and unknown to the rest of the world.
We are grateful to the PBS e-Learning Unit for consistently sharing
knowledge on e-book writing, encouraging us, and being our companion
in e-book writing discussions.
We would like to thank our colleagues, contributors, and information
source authors who have directly or indirectly inspired us to complete this
e-book.
A special thanks to our cherished family for their unwavering support and
for allowing us the time to write this e-book. Last but not least, we want to
thank God for keeping us positive and hopeful while we were writing this
e-book.

Thank you

ii Uma Devi Nadarajah

PREFACE

This ebook was written as part of an e-learning activity and to improve digital
learning, which is useful during any outbreak in addition to supporting the Go
Green initiative; going paperless. This ebook explains the fundamentals of
pneumatic circuit design for both types of linear actuators using various types of
pneumatic valves. By providing examples for each subtopic, this ebook was
created to help polytechnic students better understand pneumatic circuit design.
The steps for developing multiple cylinder circuits have been shown in detail and
thoroughly explained with examples of the questions. This topic was chosen
because students frequently struggle with designing circuits when asked
questions in class. The benefit of using this book is that it includes plenty of
exercises and answers for each question, allowing students to practise the
questions during the lesson and use them as a revision for their exam or even as
a reference while working or studying. Almost all the circuits in the examples of
this ebook have been included in its simulation video using Automation Studio
6.1 Educational Edition software to help students understand how a pneumatic
circuit works. This would improve understanding and learning experience,
especially for students who use this book for self-study or revision. This
interactive e-book would appeal to Y-generation students who prefer to use
technology for teaching and learning rather than traditional book formats.

iiI Uma Devi Nadarajah

PNEUMATIC CIRCUIT DESIGN TABLE OF CONTENT

Content Page Number

Declaration i

Acknowledgement ii

Preface iii

Table of content iv

Introduction 1

Direct method control 2

Indirect method control 5
7
Pneumatic Circuit Design for One Cylinder – AND 8
valve 9
Pneumatic Circuit Design for One Cylinder – OR 10
valve 11
Pneumatic Circuit Design for One Cylinder – 3/2-way 12
and 5/2-way valves with single and double pilot DCV 14
Pneumatic Circuit Design for One Cylinder – One-way 14
flow control valve
Pneumatic Circuit Design for One Cylinder – Pressure
sequence valve
Pneumatic Circuit Design for One Cylinder – Time
delay valve

Development of Multiple Cylinder Circuits

Classic method

Elimination of signal conflict 22

Cascade method 24

Pneumatic circuit design - Tutorial 30

Answers 34
References 42

iv POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

PNEUMATIC
CIRCUIT DESIGN

Introduction

1. Pneumatic control systems can be designed 4. To be able to design pneumatic circuits, one
in the form of pneumatic circuits. should have basic knowledge of designing simple
pneumatic circuits. With this foundation, one
2. A pneumatic circuit is formed by various would be able to move on to designing more
pneumatic components, such as cylinders, complicated circuits involving many more
directional control valves, flow control cylinders.
valves, pressure regulators, signal
processing elements such as shuttle valves, Movement of the Cylinder
two-pressure vales etc.
In this section, we will learn the basic circuit
3. Pneumatic circuits have the following for one cylinder based on
functions:
a. Direct method for single acting and
 To control the entry and exit of double acting cylinder
compressed air in the cylinders.
b. Indirect method for single acting and
 To use one valve to control another double acting cylinder
valve

 To control actuators or any other
pneumatic devices.

1 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

i. Direct Method Control a. Single-acting Cylinder Control

1. A direct control signal is used in the 1. Pneumatic cylinder can be directly controlled by
simplest level of control for a single or the actuation of the final directional control valve
double-acting cylinder. This method as shown in figure 1. These valves can be
directs cylinder actuation through a controlled manually or mechanically.
manually or mechanically actuated valve,
with no intermediate switching of the 2. This circuit can be used for small cylinders and
additional directional control valve. cylinders operating at low speeds with less flow
rate requirements.

Initial / 3. When the directional control valve is actuated by
retracting the push button, the valve switches over to the
open position, communicating the working source
to the cylinder volume. This results in the forward
motion of the piston.

4. When the push button is released, the reset
spring of the valve restores the valve to the initial
position [closed].

Extending 5. The cylinder space is connected to the exhaust
port thereby piston retracts either due to spring or
supply pressure applied from the other port.

Note: When drawing a schematic circuit, draw the circuit in
the initial / retract position only.

Figure 1: Direct control of a single-acting
cylinder

Example 1: Draw a pneumatic circuit for the following pneumatic punching machine.
Solution

Figure 2.: Pneumatic punching machine Figure 3: Pneumatic clamping machine
2
POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

Example 2: Draw a pneumatic circuit for the following pneumatic application

A small single-acting cylinder has to extend
and clamp a workpiece when a push button is
pressed as shown in Figure 4. As long as the
push button is activated, the cylinder should
remain in the clamped position. If the push
button, S1 is released, the clamp is to retract.
The power source for S1 is obtained from an
additional push button, S2. Draw the
pneumatic circuit.

Solution Figure 4: Pneumatic clamping machine

2. Figure 6 shows the direct control of a double-acting
cylinder. In this circuit, whenever the operation
button is pushed manually, the double-acting
cylinder will move back and forth once.

Figure 5: Solution for Example 2 Figure 6: Direct control of a double-
acting cylinder
b. Double-acting Cylinder Control
1. The only difference between a single-acting POLITEKNIK BANTING SELANGOR

cylinder and a double-acting cylinder is that a
double-acting cylinder uses a 5/2 directional
control valve instead of a 3/2 directional control
valve (figure 6).

3

PNEUMATIC CIRCUIT DESIGN

Example 3: Draw a pneumatic circuit for the following question using direct method.

A pneumatic system is to be designed to
operate the door of public transport vehicles.
(Figure 7). Assuming that the opening and
closing of the doors are controlled by two push
button switches ON and OFF. When the push
button switch ON is pressed, the door will
open. When the push button switch OFF is
pushed, the door will close.

Solution Figure 7.: Pneumatic punching machine

Note:
Door open (ON): Cylinder extends
Door closed (OFF): Cylinder retracts

Figure 8: Solution for Example 3

Explanation for circuit in Figure 8:
When the push button ON is pressed, the compressed air will flow from port
1 to port 2, thus the cylinder retracts and the door is open.
To close the door, the cylinder has to extend. This could be done by pressing
the push button OFF where the compressed air will flow from port 1 to port 2
and cause the cylinder to extend.

4 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

ii. Indirect Method 4. When the push button is released, pilot air
from the final valve is vented to the
a. Single-acting Cylinder control atmosphere through 3/2 NC – DCV.

1. This type of circuit (figure 9) is suitable for 5. The signal pressure required can be around
large double-acting cylinders as well as 1-1.5 bar. The working pressure passing
cylinders operating at high speeds. through the final control valve depends on
the force requirement which will be around
2. The final pilot control valve is actuated by a 4-6 bar.
normally closed 3/2 push button operated
valve. The final control valves handle a 6. Indirect control permits the processing of
large quantity of air. input signals. Single piloted valves are
rarely used in applications where the piston
3. When the push button is pressed, the 3/2- has to retract immediately after taking out
way normally closed valve generates a pilot the set pilot signal.
signal 12 which controls the final valve
thereby connecting the working medium to
the piston side of the cylinder to advance
the cylinder.

Indirect method for single acting
cylinder

single-acting cylinder

2

1 3/2-way NC single pilot
3 DCV, spring return

2
13

air service unit

Figure 9: Indirect control of single acting cylinder

5 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

b. Double-acting Cylinder control 5. When the S1 push button is released, the 5/2-
way DCV remain in actuated position until a
1. This type of circuit (figure 10) is using 5/2- signal presents at pilot 12 of the DCV.
way double pilot DCV to control the
movement of the cylinder. 6. The double-acting cylinder retracts when the
S2 push button is pressed. The output of S2
2. The pilot 14 and 12 of the 5/2-way DCV generates signals at pilot 12 of the 5/2-way
are actuated by the normally closed 3/2- double pilot DCV. Thus the DCV is de-
way push button operated DCV, S1 and actuated and back to its initial position (i.e.
S2. The final control valves handle a large right control box). This makes the compressed
quantity of air. air to the rod side and the cylinder retracts.

3. When the push button DCV, S1 is 7. The signal pressure required can be around 1-
pressed, the 3/2-way normally closed 1.5 bar. The working pressure passing through
valve generates an output signal which is the final control valve depends on the force
connected to pilot signal 14. This signal requirement which will be around 4-6 bar.
actuates the 5/2-way double pilot DCV,
connecting the working medium to the 8. Indirect control permits the processing of input
piston side of the cylinder to advance the signals. Single piloted valves are rarely used
cylinder. in applications where the piston has to retract
immediately after taking out the set pilot
signal.

Figure 10: Indirect control of double-acting cylinder POLITEKNIK BANTING SELANGOR
using 5/2-way double pilot DCV

6

PNEUMATIC CIRCUIT DESIGN

Pneumatic Circuit Design for One 4. If signals are applied to both inputs X and y, the
Cylinder compressed air flows through the valve, and the
signal appears at the output.
In this subtopic, we will learn how to
construct pneumatic circuits for one cylinder 5. AND function is also known as interlock control
using the following valves: which means control is possible only when two
conditions are satisfied.
a. Dual pressure valve (AND function)
b. Shuttle valve (OR function) 6. A classic example is a pneumatic system that
c. 3/2-way and 5/2-way valves with works only when its safety door is closed and its
manual control valve is operated. The flow
single and double pilot DCV passage will open only when both control valves
d. One-way flow control valve are operated.
e. Pressure sequence valve
f. Time delay valve

a. Circuit using dual pressure
valve (AND function)

1. This valve is the pneumatic AND valve. It is a
derivation from the non-return valve.

2. A two-pressure valve requires two pressurised
inputs to allow output from itself.

3. Figure 11 shows the working principle of this
valve. It has two inputs; X and Y and one output
2. When the compressed air is applied to either
X or input Y, the spool moves to block the flow,
and no signal appears at output 2.

2 22

X YX Y

Figure 11: Working principle of AND valve (Image sources: Virtual Labs)
7 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN Exercise 2: A double-acting cylinder is to
advance if two pushbuttons are pressed.
7. Figure 12 shows the circuit diagram of an The cylinder will retract if one of the
AND function circuit. The cylinder will work pushbuttons is released. Draw the
only when both pushbuttons valves are pneumatic circuit.
operated.

Figure 12: Control of a single-acting Figure 13: Shuttle valve (OR valve)
cylinder using AND valve

b. Circuit using shuttle valve (OR function)

1. Shuttle valve is a three-ported valve which has
two inlets and one outlet. When compressed air
enters port P1, the poppet will be pushed to port
P2 and it is blocked, thus compressed air flows
from port P1 to port A. Refer to figure 13 for the
working principle of the shuttle valve.

2. This valve is also called an OR valve because
port A is able to produce output if the
compressed air is applied to either port P1 or
P2.

3. A shuttle valve may be used, when the cylinder
or valve is to be actuated from two points, which
may be remote from one another.

8 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

4. Figure 14 shows an example of a shuttle c. Circuit using 3/2-way and 5/2-way valves
valve in a pneumatic circuit using a single- with single and double pilot DCV
acting cylinder. This example shows that the
single-acting cylinder can be operated either 1. Most of the pneumatic circuits use 3/2-way or
by manually operated 3/2-way push button 5/2-way single and double pilot DCV to control
DCV or mechanically operated 3/2-way roller the movement of the cylinder.
DCV.
2. For a single-acting cylinder, 3/2-way single
5. When either pushbutton S1 or S2 is pressed, piloted will be used meanwhile, the double-
an output signal will be produced at the OR acting cylinder uses 5/2-way single or double
valve, which causes the single-acting pilot DCV.
cylinder to extend.
3. The usage of 3/2-way and/or 5/2-way single or
double pilot DCV is depending on the
application. These directional control valves are
actuated pneumatically.

S1 S2

Figure 14: Pneumatic circuit control using Exercise 4: Name the components
shuttle valve
a. b.
6. The cylinder only can return if both
pushbuttons S1 and S2 are released. c. d.

Exercise 3: A double-acting
cylinder is to advance if one of two
pushbuttons is pressed. The
cylinder will retract if both
pushbuttons are released. Draw
the pneumatic circuit.

9 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

d. Circuit using one-way flow control valve

1. One-way flow control valve controls air flow only
in one direction which is through the air throttle
(figure15). Generally, this valve used to control
speed of actuator and is installed in the working
pressure line, between the final control valve and
the cylinder ports.

Figure 17: Meter-out method

Figure 15: One-way flow 3. In figure 17, when the 3/2-way NC push button

control valve directional control valve, S1 is pressed, a signal

2. Figure 16 shows an example of a speed control presents at port 14 of the single pilot directional
circuit for a double-acting cylinder. When the 3/2- control valve, 1.1. Air flows to the cylinder without
way NC push button directional control valve, S1 any control, however, when it comes out from the
is pressed, the signal presents at port 14 of the cylinder, air flows through the throttle path since the
single pilot directional control valve, 1.1. Air flows check valve does not allow the airflow. The air
to the cylinder through the one-way flow control coming out of the cylinder is controlled, thus the
valve. At this point, air flows choose the throttle cylinder extends slowly. This flow control method is
path since the check valve does not allow airflow. known as meter-out.

The air going into the cylinder is controlled, thus

the cylinder extends slowly. This flow control

method is known as meter-in.

Exercise 5: Identify whether the following
circuit is a meter-in or meter-out method.

a) b)

Figure 16: Meter-in method POLITEKNIK BANTING SELANGOR
10

PNEUMATIC CIRCUIT DESIGN

e. Circuit using pressure sequence valve

1. Pressure sequence valve is basically can be
used when two operations are in sequence. For
example, Cylinder A extends after Cylinder B.

2. Sequence valve generates a pneumatic signal 3 12
if the sensing pressure (signal input) is more 2 1
than the desired set pressure.
Figure 19: Actuated pressure sequence valve
3. This generated output signal is used to control Image sources: Festo
the movement of a cylinder by using it as a set
signal or reset signal to the final control valve to 8. Figure 20 shows the application that uses a
obtain forward or return motion respectively pressure sequence valve to check whether the
cylinder completes the forward motion. 5/2-way
4. A pressure sequence valve is operated on the double pilot DCV is switched by the start
same principle as operating a pressure relief pushbutton allowing the cylinder in forwarding
valve. The valve is used where a specific motion. Set the operating pressure of the pressure
pressure is needed to switch the control sequence valve higher than the forward pressure of
position in the pneumatic control system. the cylinder to operate the 3/2-way NC single pilot
DCV (combination of pressure sequence valve)
5. Figure 18 shows the structure and the after the cylinder completes the forward motion.
operating principle of a pressure sequence
valve. The port 1, 2 and 3 basically refers to a 9. A pressure sequence valve is less reliable than a
3/2-way NC pilot operated directional control limit switch to control the cylinder position and is
valve. The pilot gets the signal from the only recommendable in a special setup.
pressure signal.

6. If the pressure of the compressed air applied to
port 12 reaches the pressure set by a spring,
the valve is operated to send an output signal
to port 2 as shown in figure 19.

Screw

32 1 12

Figure 18: Pressure sequence valve Figure 20: Application of pressure sequence
Image sources: Festo
valve
11
POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

f. Circuit using time delay valve

1. The purpose of a pneumatic timer is to create a A
time delay in signal for pilot-operated circuits.

2. A time delay valve is operated for a certain Z
period after the control signal has been applied P
to control the valve. A time delay valve consists
of a one-way flow control valve, a tank and a Figure 21: Symbol of NC type time delay
compressed air-operated 3/2-way NC valve.
4. The output signal is obtainable from A in a
3. The time delay function is obtainable by certain period ( t) after the control signal has
controlling the rate of flow control of the air into been applied to z, and no output signal will be
or from the reservoir by adjusting the one-way obtainable from A if no control signal is
flow control valve. applied to Z. The valve is used for where a
certain period of delay is needed.
4. There are two types of time delay valves
depending on the type of the combined 3/2-way
valve;

a. a normally closed (NC) time delay valve
and

b. a normally open (NO) time delay valve.

a. Normally closed (NC) time delay valve Figure 22:Control circuit diagram with NC
time delay valve
1. In the NC time delay valve, the compressed air
control signal applied to Z enters into a tank at
the pressure controlled through a one-way flow
control valve. Once the pressure in the tank
reaches pressure high enough to operate the
valve, a 3/2-way valve is operated to allow the air
to flow from P to A.

2. The output signal from A is delayed for a certain
period after the control signal has been applied
to Z. The delay time is generally within 30
seconds that is adjustable by controlling the flow
rate of a one-way flow control valve.

3. Figure 21 shows the symbols and the operating
characteristics of the NC-type time delay valve.

12 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

5. Figure 22 shows the control circuit diagram with 3. Figure 24 shows the control circuit with NO time
an NC time delay valve. When the start delay valve. Valve S1 is operated to allow a
pushbutton is pressed, it triggers the operation double-acting cylinder to move forward.
of valve 1.1 through the right pilot and causes
the double-acting cylinder to advance. 4. Once the cylinder reaches the forward end
position and touches valve a1, the cylinder returns
6. When the forward motion of cylinder 1. 0 has back immediately regardless of whether valve S1
been completed, limit switch 1.3 is actuated is operated because the control signal by valve
and sends the signal to port Z of the NC time S1 for the forward motion has already been
delay valve. changed into a pulse signal.

7. When the signal presents at Z, the compressed 5. Figure 25 shows how a NO time delay valve
air enters the tank through a one-way flow produces a pulse signal when a control signal is
control valve in a certain period. Once the applied to Z.
pressure in the tank reaches enough pressure
to actuate the 3/2-way DCV, the output from A
switches the position of valve 1.1. through the
left pilot which allows the cylinder to retract.
This retraction occurs after a certain period
from the actuation of valve 1.3 (limit switch).

8. Once the cylinder starts the backward motion,
valve 1.3 is returned to its normal position, and
causes the time delay valve also returns to its
normal position.

b. Normally Open (NO) Time Delay Valve

1. Normally open time delay valve is operated on Figure 24: Control circuit diagram using
the same principle as operating an NC time NO time delay valve
delay valve. The only difference is that a NO
time delay valve uses a NO 3/2-way valve. A
Z
2. Figure 23 shows the symbol and operating
characteristics of the NO time delay valve. The PR
valve allows the compressed air to flow from P
to A. If the control signal is applied to Z, no
output is obtained from A for a certain period.

A
Z

PR Figure 25: NO time delay valve as a pulse
signal
Figure 23: Symbol of NO type time delay

13 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN
Development of Multiple Cylinder Circuits

1. Multi-cylinder pneumatics circuits can be 3. The position of the cylinder and the resultant
designed in various methods. There is no actuation of the final control element are
universal circuit design method that suits all determined by sensors. The type of sensor
types of circuits. Some methods are commonly used in this method is the mechanical limit
used for compound circuits but would be too switch.
expensive for simple circuits. There are five
common methods used by engineering and they 4. The movement of various cylinders can be
are given below achieved by the activation of limit switches of
a. Classic method or Intuitive method different cylinders where the signal will be
b. Cascade method used to set or reset the signal to the final
c. Step counter method control valves.
d. Karnaugh–Veitch method
e. Combinational circuit design 5. It is important to draw the motion diagram to
understand the sequence of the actuation of
2. In this section, only two methods; the classic various signal input switches, limit switches
method and cascade method are discussed. and sensors.

i. Classic method or intuitive method 6. Motion diagram indicates the status of the
cylinder position in a particular step; whether
1. In the classic method, the circuit can be extended or retracted.
designed by use of pneumatic general
knowledge following the sequence intuitively. In Example 4:
general, the steps are as follows:
Two cylinders are used to transfer parts from a
Step 1: Write down sequences and draw magazine onto a chute. When a push button is
motion diagrams pressed, the first cylinder extends. Pushing the
part from the magazine and positioning it in
Step 2: Draw in cylinders and control valves preparation for transfer by the second cylinder
and complete the circuit intuitively onto the outfeed chute. Once the part is
transferred, the first cylinder retracts, followed by
Step 3: Analyse the circuit to ensure the the second. Confirmation of all extended and
functionality of the circuit. retracted positions is required. Draw the
pneumatic circuit using the classic method.

2. In most pneumatic applications, more than one POLITEKNIK BANTING SELANGOR
cylinder is used. The movement of the
cylinders is automatic and is designed in such
a way as the required sequence.

14

PNEUMATIC CIRCUIT DESIGN

Step 1: Write down sequences and draw motion
diagrams

Step 1a: Identify the sequence

Process Pushing from magazine (First
cylinder) & transferring to
outfeed chute (second cylinder)

Number of 2 Figure 27: Displacement time diagram
cylinders (because 2 processes)
Step 1c: Analyse the input and output signal
Cylinder A First cylinder
Input signals:
Cylinder B Second cylinder Cylinder A – Limit switch at home position a0

Represent First cylinder extends: (A+) Limit switch at home position a1
the process First cylinder retracts: (A-)
in notational Second cylinder extends: (B+) Cylinder B - Limit switch at home position b0
form Second cylinder retracts: (B-) Limit switch at home position b1

Sequence First cylinder extends, second Output Signal
cylinder extends, first cylinder The forward motion of cylinder A ( A+)
retracts, second cylinder retracts The return motion of cylinder A (A-)
The forward motion of cylinder B( B+)
Therefore the sequence for this example is as The return motion of cylinder B( B-)
follows:

A+ B+ A- B-

Step 1b: Draw motion diagram

Note:

Cylinder A, the sensors could be labelled as
a0 and a1 for easy identification.

a0 a1
Cylinder A

Figure 26: Displacement step diagram POLITEKNIK BANTING SELANGOR
15

PNEUMATIC CIRCUIT DESIGN

Step 1d: Sequence flow – link input and output Figure 28b: Sequence flow
signal
Step 2: Draw in cylinders and control valves
a. A+ action generates sensor signal a1, and complete the circuit intuitively
which is used for B+ motion

b. B+ action generates sensor signal b1,
which is used for B- motion

c. B- action generates sensor signal b0,
which is used for A- motion

d. A- action generates sensor signal a0,
which is used for A+ motion

The information above can be represented graphically Step 2a: Draw the power circuit
as shown in figures 28a and 28b (sequence flow).
a. Draw cylinders A and B as shown in Figure 29.
b. Draw directional control valves 1.1 and 2.1 in

unactuated conditions
c. Mark the limit switch positions for cylinders A (a0

and a1) and B (b0 and b1)

Figure 28: Input and output signal link

Figure 29: Power circuit

Step 2b: Draw the control circuit

a. Based on Figure 28b, connect all the
limit switches accordingly, e.g. the Start
pushbutton and limit switch b0 send
signals to A+ and limit switch a1 sends
signals to B+ to extend cylinder B.

Figure 30: Control circuit (in the red dotted box) POLITEKNIK BANTING SELANGOR
16

PNEUMATIC CIRCUIT DESIGN

Step 3: Analyse the circuit to ensure its
functionality.

Step 3a: Analysis of the pneumatic circuit 4. Again check for the presence of the signal at the
other end, port 12 (B-) of valve 2.1. The signal is
1. Figure 31 shows the complete circuit for not present at port 12 (B-) of valve 2.1 (because
sequence A+ B+ A- B-. When the start button is a0 is not pressed, A is already in an extended
pressed, the signal appears at port 14 (A+) of position now) hence there is no signal conflict.
valve 1.1 through limit switch signal b0.
5. The signal applied to port 14 (B+) of valve 2.1
2. Always check if there is a signal present at the causes the shifting of DCV 2.1 and cylinder B to
other end; i.e. port 12 (A-) of valve 1.1. Notice extend.
that the signal is not present at port 12 (A-) of
valve 1.1. (Because b1 is not pressed by 6. Now, when cylinder B fully extends, it generates
cylinder B). There is no signal conflict and valve a limit switch signal b1, which is applied to port
1.1 is able to move. So cylinder A advances to 12(A-) of valve 1.1. This causes cylinder A to
the forward position. retract and a0 is pressed. There is no signal
conflict, as a0 and a1 are mutually exclusive
3. When cylinder A advances to the forward signals.
position, it generates a signal at limit switch
signal a1, which is applied to port 14 (B+) of 7. When cylinder A is fully retracted, it generates a
valve 2.1, thus cylinder B advances to the limit switch signal a0, which is applied to port 12
forward position. (B-) of valve 2.1 and cylinder B retracts.

Figure 31: Circuit for sequence A+ B+ A- B-
17 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

The following images are screenshots of simulation software for sequence A+ B+ A- B-

Initial state Position when Cylinder A extends

Position when Cylinder B extends Position when Cylinder A retracts

Note: red line indicates the line is
pressurised (signal presents) and the blue
line indicates the line is unpressurised (no
signal)

Figure 32: Simulation for sequence A+
B+ A- B-

Position when Cylinder B retracts

18 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

Example 5: Solution:
In a workshop, a drilling operation is to be
performed using a stamping machine. Before The solution for this method must
drilling, the workpiece has to be clamped under the include all three steps as mentioned
stamping station. Then drilling tool bit comes and earlier. Let’s start.
performs the drilling operation. The workpiece must
be unclamped only after the drilling operation.
Draw the pneumatic circuit using the classic
method.

Step 1: Write down sequences and draw motion Step 1b: Draw motion diagram
diagrams
Figure 33: Displacement step diagram
Step 1a: Identify the sequence
Figure 34: Displacement time diagram
Process Drilling & Clamping
POLITEKNIK BANTING SELANGOR
Number of 2
cylinders (because 2 processes)

Cylinder A Clamping

Cylinder B Drilling

Represent Clamp: cylinder A extends (A+)
the process Unclamp: Cylinder A retracts (A-)
in notational Drill tool bit comes down:
form Cylinder B extend (B+)
Drill tool bit goes up: Cylinder B
retracts (B-)

Sequence 1. Clamp workpiece (A+)
2. Drill tool bit comes down (B+)
3. Drill tool bit goes up (B-)
4. Unclamp (A-)

Therefore the sequence for this
example is as follows:

A+ B+ B- A-

19

PNEUMATIC CIRCUIT DESIGN

Step 1c: Analyse the input and output signal

Input signals: Figure 35b: Sequence flow
Cylinder A – Limit switch at home position ao

Limit switch at home position a1

Cylinder B - Limit switch at home position bo Step 2: Draw in cylinders and control valves
Limit switch at home position b1 and complete the circuit intuitively

Output Signal Step 2a: Draw the power circuit
The forward motion of cylinder A ( A+)
The return motion of cylinder A (A-) a. Draw cylinders A and B as shown in Figure 36
The forward motion of cylinder B( B+) b. Draw directional control valves 1.1 and 2.1 in
The return motion of cylinder B( B+)
unactuated conditions
Step 1d: Sequence flow – link input and output c. Mark the limit switch positions for cylinders A (a0
signal
and a1) and B (b0 and b1)

a. A+ action generates sensor signal a1, Figure 36: Power circuit
which is used for B+ motion Step 2b: Draw the control circuit

b. B+ action generates sensor signal b1,
which is used for B- motion

c. B- action generates sensor signal b0,
which is used for A- motion

d. A- action generates sensor signal a0,
which is used for A+ motion

The information above can be represented
graphically as shown in figure 35a and 35b
(sequence flow).

Figure 35a: Input and output signal Figure 37: Control circuit (in the red dotted box)
link
POLITEKNIK BANTING SELANGOR
20

PNEUMATIC CIRCUIT DESIGN

Step 3: Analyse the circuit to ensure its
functionality.

Step 3a: Analysis of the pneumatic circuit Figure 39: Pneumatic circuit after cylinders A and
B are extended
1. Initially, limit switch a0 is actuated because it
is pressed by Cylinder A. When the start 6. Signal applied to port 14 of valve 2.1 causes
button is pressed, the signal appears at port the DCV 2.1 to switch over its position and
14 of valve 1.1 through limit switch signal a0. causes cylinder B to extend.

2. At the same time, there is a signal present at 7. When cylinder B fully extends, limit switch b1 is
the other end (12) of valve 1.1. This results in actuated and the output signal from limit switch
signal conflict and valve 1.1 is unable to move b1 is applied to port 12 of valve 2.1.
as shown in figure 38.
8. However in figure 40, it can be seen that signal
is also present at port 14 of valve 2.1 because
a1 is also pressed by cylinder A. This results in
signal conflict and valve 2.1 is unable to switch
its control position.

Figure 38: Signal conflict at valve 1.1 Figure 40: Signal conflict at valve 2.1

3. Now, let’s assume b0 is somehow
disengaged for time being, so that valve 1.1
can actuate and consequently cylinder A can
extend when the start button is pressed.

4. When cylinder A fully extends, it generates a
signal at limit switch a1, which is applied to
port 14 of valve 2.1 as shown in figure 39.

5. This time, no signal is present at the other
end (12) of valve 2.1 hence there is no signal
conflict.

21 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN Elimination of Signal Conflict

9. Let us assume b1 is somehow disengaged for 1. The interference between the control signals in
time being, so that valve 2.1 can switch over and multi cylinders circuit can be eliminated by
consequently cylinder B can retract as in figure using various methods such as:
41.
a. Idle return roller
10. In figure 42, when cylinder B is fully retracted, b. Reversing valves ( memory valves)
limit switch b0 is actuated and the output signal of c. Modules as a combination of valves
limit switch b0 is applied to port 12 of valve 1.1.
2. Cascading method uses the reversing valves
11. Since there is no signal present at port 14 of (also known as group changing valves) and
valve 1.1, thus there is no signal conflict and the step counter method uses modular valves.
valve 1.1 can switch over causing Cylinder A to Both the idle return roller and cascade method
retract. are discussed in a subsequent section of this
chapter.

Figure 41: Position when cylinder B is Use of Idle Return Rollers.
reversing (B -)
1. An idle-return roller limit switch is a
directional control valve that is operated in
one way.

2. If the continued signal has been generated
from a limit switch, an idle return roller valve
is used to eliminate the interference (signal
conflict) between control signals. The two
designs of the idle roller are shown in figure
43

Figure 42: Position when cylinder A has Figure 43: Two designs of Idle return rollers
retracted fully (A-) (Image sources: SlideToDoc.com)

22 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

8. Using the idle return roller valve is the most
simple and economical solution to eliminate
signal conflict.

9. With simple circuit design and wiring, and easy
maintenance of the control system, the solution
is much used for a simple sequence control with
2 or 3 cylinders.

10. The drawback of using idle return rollers valve is
that

a. It is difficult to precisely verify the position
which means the end position cannot be
sensed accurately.

b. It is not reliable because unable to configure
an AND logic circuit with other control signals
because the limit switch only generates a
short pulse signal.

Figure 44: Actions of idle return rollers c. The length of the output pulse signal from the
(Image sources: SlideToDoc.com) idle return roller valve varies depending on
the speed of the cylinder. It is noted that the
3. Figure 44 shows how the idle return roller valve length of the pulse signal may not be enough
operates. The roller lever valve with idle return is for proper operation if the cylinder moves too
actuated when the roller lever is traversed by the fast. (fast control system cannot be set up)
cam of a cylinder in a certain direction (Figure 44a).
When the cylinder is fully extended, the valve is 11. In the previous sequence problem, we have
returned to its initial position by a return spring. identified that roller valves b1 and a1 are
(Figure 44 b) responsible for signal conflicts. To eliminate the
problem of signal conflicts the roller valves b1
4. When traversed in the reverse direction, the roller and a1 are to be replaced by idle return rollers
lever has an idle return and the valve is not as shown in figure 45.
actuated. (Figure 44 c and d)

5. As a result, the valve generates a short output pulse
during the forward motion of the cylinder. The idle
return mechanism also allows the cylinder to retract
without re-activating the valve.

6. Hence, in the end position or during the return
motion of the piston, the valve does not get
actuated, and no output signal is produced.

7. For the generation of short output pulse by the idle- POLITEKNIK BANTING SELANGOR
return roller valve during the return motion of the
cylinder, this valve may be positioned in the
opposite direction as compared to the case during
the forward motion of the cylinder.

23

PNEUMATIC CIRCUIT DESIGN

Figure 45: Solution using idle
return roller valve for sequence A+
B+ B- A- (Example 5)

Figure 45 shows the solution for sequence A+ B+ B- A- using the idle–return rollers valves. The valves
are placed at limit switch b0 and a1 because these are the limit switches that cause signal conflicts.

Cascade method 2. A cascade control circuit uses non-directional
1. Signal elimination by means of a reversing limit switches and memory type 4/2-way
valves or 5/2-way valves, which are generally
valve or bi-stable memory valve is often used. used to control the double-acting cylinders, to
control the traffic of control signals.
Steps to develop cascade circuit

1. Identify the sequence from the given task. 4. Draw the power circuit

2. Draw the motion diagram 5. Draw the pressure lines, group changing
circuit and control valves above and below the
3. Find the following information from the sequence: pressure lines

❑ Number of groups = N; (Note: the same cylinder 6. Analyse the circuit.
cannot be in the same group)

❑ Number of pressure lines = N; (Note: same as
the number of groups)

❑ Number of reversing valves = N – 1; (Note:
Number of groups – 1)

24 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN Figure 46: Sequence flow for A+ B+ A- B-

Example 6a:
Draw the sequence flow for A+ B+ A- B-

Find the following information from the
sequence:
❑ Number of groups = N; (Note: the same

cylinder cannot be in the same group)
❑ Number of pressure lines = N; (Note:

same as the number of groups)
❑ Number of reversing valves = N – 1;

(Note: Number of groups – 1)

Control circuit below the pressure
lines

Note: For 3 groups, 3 Pressure lines Note: For 2 groups, 2 Pressure lines
and 2 Reversing memory valves and 1 Reversing memory valves

Signal 3

Figure 47: Group changing connection
25 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN
Example 6b:
Draw the pneumatic circuit for A+ B+ A- B- using the cascade method based on sequence flow in Example 6a

Solution:

4. Draw the power circuit

Figure 48: Power circuit
5. Draw the pressure lines, group changing circuit and
control valves above and below the pressure lines as shown in Figure 49.

Figure 49: Cascade circuit for sequence A+ B+ A- B- POLITEKNIK BANTING SELANGOR
26

PNEUMATIC CIRCUIT DESIGN
6. Analyse the circuit.

Figure 50: Cascade circuit for sequence A+ B+ A- B-

1. Initially, limit switches a0 and b0 are actuated 3. When cylinder B touches limit switch b1, a
because cylinders are pressing them. When the
start push button is pressed, the signal is present signal is present at Signal 2 of the group
at signal 1 of the group changing valve and it is changing valve. Now, the group changing valve
actuated since there is no signal present at signal switches its position to the right control box and
2. pressure line L2 is powered up. The components
connected to L2 are now getting the pressure
2. This causes all the components (A+, a1 and b1) source and cylinder A retracts and actuates limit
connected to the pressure line L1 to be powered switch a0. This actuation causes cylinder B to
up. At this point, cylinder A extends first and retract and actuates b0 (Note: b1 is de-actuated,
actuates a1 (note: a0 is de-actuated). This no signal at Signal 2)
actuation makes cylinder B extends.

27 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN
Example 6
Cylinder A extends to clamp the workpiece before cylinder B extends to perform the stamping job. Cylinder A
can return back only after cylinder B has retracted fully. Design the pneumatic circuit using the cascade method.

Solution:

Figure 51: Solution for sequence A+ B+ B- A-
28 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN
Example 7
Design pneumatic circuit for A+ C+ C- B+ A- B- using cascade method. Show steps to develop the circuit.
Include sequence flow and step diagram in the solution.

Solution:

Motion diagram

Figure 52: Solution for Example 7
29 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

PNEUMATIC
CIRCUIT DESIGN
TUTORIAL

Single cylinder circuit design

1. The allocating device supplies aluminium valve
blanks to a machining station. The piston rod of
the single-acting cylinder (1.0) is made to
advance by operating a push button. After
releasing the actuating button, the piston rod
returns. Draw the pneumatic circuit using direct
and indirect methods.

Figure 54: Sorting device for metal stampings

Figure 53: Allocating device 3. With the help of the vertical switching point, soft
cool (lignite) briquettes are to be fed to an upper
2. Figure 2 shows a sorting device for metal or lower conveyor, according to selection. The
stampings. When the push button on the actuating destination of the swivelling slide (upper or lower)
valve is pressed, metal stampings lying in random is decided by means of a valve with a selector
positions are sorted out and transferred to a switch. The upward motion of the double-acting
second conveyor belt. The forward motion of the cylinder (1.0) is to take place in t1 = 3 seconds;
piston rod of a single-acting cylinder (1.0) takes t = the downward motion in t2 = 2.5 seconds.
0.4 seconds. When the push button is released, Pressure on both sides of the piston is indicated.
the piston rod travels to the retracted end position. In the initial position, the cylinder assumes the
A pressure gauge is fitted before and after the one- retracted end position. [Lignite briquettes are the
way flow control valve. Draw the pneumatic circuit classic fuel for
using direct and indirect methods. traditional solid-fuel appliances like automatic
stoves, cooking stoves and stand-alone stoves.
Frequently used in combination with wood in
modern solid-fuel appliances.]
Draw the pneumatic circuit using direct and
indirect methods.

30 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

The return stroke, also started by a push button,
can only take place when the double-acting
cylinder (1.0) has reached its forward end position.
Draw the pneumatic circuit using the indirect
method.

Figure 55: Vertical switching point for
briquettes

4. Operation of two identical valves by push Figure 57: Marking machine
button causes the forming tool of an edge
folding device to thrust downwards and fold 6. A plastic component is to be embossed by using
over the edge of a flat sheet of cross-sectional a die which is powered by a double-acting
area 40 x 5. If both – or even just one – push cylinder. When a pushbutton, S1 is pressed, the
button is released, the double-acting cylinder cylinder extends to perform the embossing
(1.0) slowly returns to the initial position. The process. The return of the die is to occur only
cylinder pressures are indicated. Draw the when the cylinder rod has fully extended to the
pneumatic circuit using the indirect method. embossing position and the preset pressure is
reached. A roller lever valve, S2 is to be used to
Figure 56: Edge folding device confirm the full extension. The signal for
retracting must only be generated when the
piston rod has reached the embossing position.
The pressure in the piston chamber is indicated
by a pressure gauge. Construct the pneumatic
circuit using the indirect method. The circuit
should be labelled clearly.

5. Surveyor’s measuring rods in 3 or 5 m length
are marked in red with 200 mm graduations.
There is a choice of two push buttons to start
the forward movement of the measuring rods
via cylinder (1.0), which has the exhaust air
throttled.

31 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

7. A double-acting cylinder guides cylinder pins 10. Sheet metals are to be U-formed using a
towards a measuring device. The pins are bending machine which uses a double-acting
separated by means of a continuous to-and-fro cylinder as shown in Figure 1. By pressing a
movement. The oscillating motion (use limit switch push button S1, the cylinder thrust forward to
a0 and start pushbutton, S1 to extend meanwhile bend the sheet metal. By pressing another push
limit switch, a1 to retract) can be started by means button, S2, the cylinder is returned to its initial
of a valve with selector switch, S1. The duration of position. Construct the pneumatic circuit using
the forward stroke of the cylinder is to be t1= 0.6 s, the indirect method.
and the return stroke t3 = 0.4 s. The cylinder is to
remain in the forward end position for t2 = 1.0 s, 11. Sheet metals are to be U-formed using a
resulting in a cycle time of t4 = 2.0 s. Construct bending machine which uses a double-acting
the pneumatic circuit. cylinder. By pressing a push button S1, the
cylinder thrust forward to bend the sheet metal.
8. An electrically heated rail is pressed onto a The cylinder is returned to its initial position after
rotatable cold drum by a double-acting cylinder it reaches the end position which is confirmed
and welds a continuous plastic sheet into pieces by a roller limit switch. Construct the pneumatic
of tubing. The forward stroke is triggered by circuit using the indirect method.
means of a push button. The maximum cylinder
force is set at 4 bar via a pressure regulator with a 12. Parts are accumulating on a conveyor belt and
pressure gauge. (This prevents the welding rail waiting to be released and transferred to the
from damaging the metal drum). The return stroke next phase of assembly. Technicians at three
is not initiated until the forward end position has (3) stations need to control the gate release
been acknowledged and the pressure in the piston mechanism to have parts sent to their assembly
area has reached 3 bar. The supply air is station. You are required to design the
restricted for the movement of the cylinder. The pneumatic circuit where there are three
flow control should be adjusted so that the pushbuttons (each at a station). When any of
pressure increase to 3 bar only takes place after t1 the push buttons is pressed, the single-acting
= 3 seconds after the cylinder has reached the cylinder is advanced to open the gate and
forward end position (the foil edges which are release the part to the assembly station. The
overlapped are welded by the heated welding rail cylinder retracts when all the push buttons are
as increased pressure is applied). Restarting is released.
only possible when the retracted end position has
been reached and a time of t2 = 2 seconds has 13. The allocating device supplies aluminium valve
elapsed. Reversing a 3/2-way valve with a blanks to a machining station. By operating any
selector switch causes the control to be switched two identical push buttons, the piston rod of the
to a continuous cycle. double-acting cylinder (1.0) is made to advance.
The piston rod is made to retract by pressing
9. Bulk loose material is to be emptied from a dump another pushbutton and the cylinder only
hopper by means of a double-acting cylinder. By retracts once it has reached the forward end
pressing a push button S1, the dump hopper is position. Design the pneumatic circuit.
tilted and the bulk loose materials are emptied out.
By pressing another push button, S2, the dump
hopper is returned to its initial position. Construct
the pneumatic circuit using the indirect method.

32 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

Multi cylinders circuit design

1. Two clips are to be riveted together on a semi- 5. Two cylinders are used to transfer parts from a
automatic press. Components and rivets are magazine onto a chute. When a push button is
positioned by hand and then removed by hand on pressed, the first cylinder extends, pushing the
completion of the riveting operation. The automated part from the magazine and positioning it in a
part of the working cycle consists of the holding chute. Then the cylinder retracts. Next, the
and clamping of the components by cylinder A and second cylinder pushes the part from the chute to
also the riveting by cylinder B. The clamp must be a box. Once the part is transferred to the box, the
activated before the riveting cycle begins and second cylinder retracts. Design a pneumatic
deactivated at the end of the riveting cycle. The circuit for the given problem using the classic
operation is started by pressing a pushbutton, method.
Start. Design a pneumatic circuit for the given
problem using the classic method. 6. In a press shop, stamping operation is to be
performed using a stamping machine. Before
2. In a production line, parts need to be clamped for stamping, the workpiece has to be clamped under
drilling operations. The technician needs to activate the stamping station. Then stamping tool comes
and deactivate the pneumatic clamp that holds the and performs the stamping operation. The
part in a fixture on the drilling machine. The clamp workpiece must be unclamped only after the
must be activated before the drilling cycle begins stamping operation.
and deactivated at the end of the drilling cycle. The a. Design a pneumatic circuit for the given
operation is started by pressing a pushbutton, problem using the classic method. Your
Start. Design a pneumatic circuit for the given solution must include the following
problem using the classic method. i. Sequence flow diagram.
ii. Displacement-step diagram.
3. In a production line, parts need to be clamped for
stamping operation. The technician needs to b. For the above questions, is there any signal
activate and deactivate the pneumatic clamp that conflict? If yes, at which point does it occur,
holds the part in a fixture on the stamping machine. analyse the occurrence of the signal conflict
The clamp must be activated before the stamping clearly.
cycle begins and deactivated at the end of the
stamping cycle. The operation is started by c. Redesign the above circuit using the
pressing a pushbutton, Start. Design a pneumatic cascade method. The solution must be
circuit for the given problem using the classic shown clearly.
method.

4. Two cylinders are used to transfer parts from a
magazine onto a chute. When a push button is
pressed, the first cylinder extends, pushing the part
from the magazine and positioning it in preparation
for transfer by the second cylinder onto the outfeed
chute. Once the part is transferred, the first cylinder
retracts, followed by the second cylinder. Design a
pneumatic circuit for the given problem using the
classic method.

33 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN PNEUMATIC CIRCUIT
Exercise 1 DESIGN EXERCISE

Answers

Exercise 3

Exercise 2 Exercise 4
34 a. 3/2-way NC single pilot, spring return

DCV
b. 5/2-way double pilot DCV
c. 3/2-way NC double pilot DCV
d. 5/2-way single pilot, spring return DCV

Exercise 5
a. Meter-in method controls retract
b. Meter-out method controls retract

POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN

PNEUMATIC CIRCUIT
DESIGN TUTORIAL

Answers

Single cylinder circuit design - Answers Question 3

Question 1

Question 2 Question 4

Indirect method

0 bar
0 bar

35 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN Question 6
Question 5

Question 7

Question 9

Question 10 & 11 Question 12
36
POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN
Question 8

Multi cylinders circuit design - Answers Classic circuit

Question 1, 2 and 3
Sequence flow

Displacement step diagram

However, this circuit creates signal conflicts at roller
limit switches b0 and a1. To eliminate the signal
conflict, use the idle return roller limit switch or
cascade method as shown below.

37 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN
Classic circuit using idle return roller valve
Cascade method

38 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN Classic circuit
Question 4

Sequence flow

Displacement step diagram

Cascade method

39 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN Classic circuit
Question 5

Sequence flow

Displacement step diagram

Question 6 Question 6a (ii)
Question 6a (i)
Question 6a (iii) Question 6b

40 There is a signal conflict occurring in
the circuit. The first signal conflict
occurs he DCV 1.1 at pilot 12. The
presence of the signal is due to the
limit switch b0, which is pressed by
Cylinder B. The second signal conflict
occurs at DCV 2.1 at pilot 14. This is
because the signal present at limit
switch a1 is pressed by Cylinder A
which is in the extended position.

POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN
Question 6c

41 POLITEKNIK BANTING SELANGOR

PNEUMATIC CIRCUIT DESIGN
References
1. SMC Pneumatics Inc. (1997). Basic pneumatics (Rev. 0100 ed.) [E-book].
2. FESTECH Factory Automation Expert Group. (2007). Practical pneumatics FESTECH.
3. Jainik Makwana (2019). Oil Hydraulics and Pneumatic Chapter 7 Pneumatic Circuit. Department of
Mechanical Engineering Darshan Institute of Engineering & Technology, Rajkot
4. P. Croser, F. Ebel (2002). Pneumatics Basic Level (Edition 10). Festo Didactic GmBH & Co.
5. D. Waller, H Werner (2002). Pneumatics Workbook Basic level (Edition 04). Festo Didactic GmBH &
Co.

“Education is one thing no one can take away from
you.”

—Elin Nordegren

42 POLITEKNIK BANTING SELANGOR