Introduction to Industrial Automation

position pneumatic circuit and components (a), and its automation circuit (b).

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Elements of Electro-Pneumatic Components 

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retraction of the piston rods), then the description of the automation (especially the steps that 

every cylinder should execute for completing the overall automation task) is problematic. Thus, in 

these cases, it is suggested to utilize diagrams that can represent the movements for every cylinder 

in a simplified way, including possible combinations for combined tasks. In general, there exist 

two types of such diagrams: the diagram of “position-steps” and the diagram “position-time”. The 

word “position” is referring to the position that the piston has (in or out), the word “steps” is refer-

ring to the application steps that concerns the operation of the cylinders, while the word “time” is 

referring to the time that a step lasts in the application. In the following example, the usefulness of 

these diagrams in complex industrial automations is presented, as well as the need for using them 

together with the pneumatic and electric circuit.

In Figure 5.20, a change in the translation level of goods is achieved from the conveyor belt M

A

 

to the conveyor belt M

B

, with the help of the corresponding cylinders A and B. For the proper opera-

tion of this process, the A cylinder should be retained in extension, while the piston B will push the 

object toward the conveyor belt M

B

. In a different case, the object will most likely either fall down 

or collapse by the piston and the fixed parts of the conveyor belt M

B

. This condition can be very 

easily expressed during the design stage of the automation with the diagram “position-steps” (shown 

in Figure 5.21) and more especially from Step 2 to Step 3. All the desired movements of the two 

cylinders that are described in this diagram in a very simple way also helps the design of the overall 

automation circuit. Another important desire in this automation is the fact that the conveyor belt 

M

A

 should not send objects while the piston A is still in extension, because the object will fall to 

Cylinder A 

1

2

3

Cylinder B

M

A

M

B