Question 1.
FIGURE 1 shows a pneumatic circuit diagram used for air supply and exhaust in an automatic control system.
(a) Name all symbols (including pipelines) used in the system.
(b) Number the ports of each DCV.
(c) Classify the sections of the components in the circuit.
(d) State how the system works.
(e) State the functions of valves 1 and 2.
Question 2.
FIGURE 2 shows a pneumatic circuit in which four actuators are controllal.
(a) State the sequence in which the cylinders operate on the operation of the start valve.
(b) Show, with the aid of a schematic diagram, how an electronic controller could be included in the circuit to control the sequence of cylinder operations.
Question 3.
Design and draw a circuit using the cascade system to operate two cylinder (A and B) which, m the operation of a start valve, products the sequence A - B + B - A+. The cylinders should park in the pcsitiorm B -A + when the start s-witdi is in the 'off' position.
Question 4.
Modify the circuit designed fur question 3 to provide an emergency stop which will park both cylinders in the extended position (it. A + B +).
Question 5.
Modify the circuit designed for question 3 to provide a fail safe. The fail safe should:
(a) act in the event of a reduced pressure at inlet to the group selecting value
(b) park the cylinders in the retracted paiition.
Question 6.
FIGURE 3 shows a hydraulic circuit.
(a) State the name and purpase of the aimponents shown in the circuit diagram .
(b) Explain the operation of this circuit. I Explain the limitations of this circuit in terms of 'speed control'.
Question 7.
Modify the design of the circuit shown in FIGURE 3 and draw a circuit diagram to provide rotary actuation in both directions using a single direction pump (to replace the bi-directional pump) and providing a means of pitventing over-speeding in the case of an overhauling load in both directions.