Hydraulic and Pneumatic Systems: Circuit Design and Operation

SOLUTION TO THE QUESTIONS
1. (a)
1- Sequence valve 1 for retraction
2- Sequence valve 2 for inlet supply
3- Directional control valve 1 (spring-operated)
4- Directional control valve 2
5- Check valve
6-Main supply line
7-Return line
8-Pilot line
6
8
7
1
2
3
3
2
1
4

(b) Directional control valves, check valves, sequence valves
DCV 1: 3 position, 4 way and spring operated
DCV2: 3 position, 4 way and spring operated
(Check figure 1 for ports numbering)
(c) The cylinder section
Control valves constituting directional control valve
Actuator –pneumatic drive
Return line
(d) How system works
-During inlet supply to cylinder, valve 2 is closed while 1 is left opened
-Air rushes through valve 1
-The check valve ensures correct sequencing is followed
-As the plunger pushes forward and the check valve closes line 1 hence valve is closed
-The compressed air exits via valve 2 and is directed to the action centre
(e) Functions of (1) and (2):
1- Regulates flow of air into cylinder for extensions
2-Regulates flow of air out of cylinder in retraction mode
2. (a) -A,+B,+C,-D and the return : +D,-C,-B,+A full cycle
(b) Electronics controller integration
The controller shown is integrated in circuit figure 2 below