Introduction to Industrial Automation

Figure 5.20  A two-cylinder arrangement for level changing in a production line.

1

2

3

4

5 = 1

Cylinder A

Cylinder B

Up

Down

Out

In

Steps

Figure 5.21  Position-step diagram of the two-cylinder arrangement shown in Figure 5.20.

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  Introduction to Industrial Automation

the ground. However, the operation of the M

A

 is not included in the diagram “position-steps” (it is 

relevant only for cylinders) and thus this condition is not expressed elsewhere in this diagram.

In many applications, even if the extension of a cylinder lasts for quite a long time (a few 

seconds), its retraction should be faster in order to keep production cycles to a minimum. As an 

example, the extension of cylinder B in Figure 5.20 should last for a sufficient time, since the 

objects might be heavy and fragile. Thus the piston rod, in this case, should move at quite a slow 

speed, pushing the object gently to the conveyor belt M

B

. However, during the return of the 

piston, a fast movement could be achieved, since there is no reason for delaying this return. In 

the case that this difference in the time execution of the various tasks makes sense for the proper 

implementation of an industrial automation, the diagram’s “position-time” can be utilized, such 

as the one presented in Figure 5.22, related to the application in Figure 5.20.