Design and Technology
Unit 1 – Introduction to Pneumatics Energy can be stored by compressing air. 1. Put these sentences into the correct order to make a description of how pneumatics use air to do useful work. Air is taken from the atmosphere by the pump in the compressor The compressed air pushes a piston that is inside the cylinder The pump compresses the air into a strong storage tank called a receiver The moving piston does useful work The compressed air is stored in the receiver until it is needed A control system releases the compressed air into a pneumatic cylinder 2. In air preparation why do you need Dryer Filter Lubricator Gauge 3. What are the four main advantages of pneumatic systems? Write a sentence explaining each one. • . •
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. 4. What are the two main disadvantages of pneumatic systems? Write a sentence explaining each one. • . •
. 5. List 8 safety points when using pneumatic systems • . •
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. 6. Draw the safety symbol used to warn of possible hazard from compressed air. Unit 2 3 Port Valve Circuit Diagrams Three Port Valve This is the circuit diagram for a 3 port valve. It is very often called a 3/2 valve – this is because it has 3 ports and two possible states. It can be Actuated (button pushed) or Unactuated (button not pushed). The symbol is made up of two boxes. One box shows the actuated state with the way open for air to flow from port 1 to port 2. The other box shows the unactuated state with port 1 blocked, and the way open for air to flow from port 2 to port 3. The circuit diagram needs to have the ‘actuators’ added to the symbol to show what type of valve it is and what makes it work. This diagram is for a push button 3/2 valve with spring return These symbols are also drawn onto the valve symbols: Port 1 is always connected to the air supply Port 3 is the exhaust port. This does not always have a connection for attaching a pipe to it.
Actuators These are the different variations of the basic 3 port valve that can be used to switch the air supply on through the valve or to block it. The commonest types of 3/2 valves are Push button/spring return 3/2 valve Solenoid/spring return 3/2 valve Lever/spring return 3/2 valve Unit 2.1 – Single Acting Cylinder and 3 Port Valve Single Acting Cylinder Label the single acting cylinder and circuit diagram symbol. Label the ‘+’ (extended) and ‘ ‐ ’ (retracted) states. The piston is extended when ………………………………………………… The piston retracts when …………………………………………..………. and is pushed back by the force of the ……………………. Three Port Valve
Label the 3 port valve circuit diagram symbol. Build and test these circuits Single Acting cylinder and push button 3/2 valve Single Acting cylinder and lever 3/2 valve Unit 2.2 – Piston Speed Control Flow Control Valve There are two types of flow control valve : – Uni‐directional flow control valves reduce the flow of air in one direction only Bi‐directional flow control valves reduce the flow of air in both directions Uni‐directional flow control valve Bi‐directional flow control valve Build and test the following circuits. Single acting cylinder – speed Single acting cylinder – speed control of control of the outstroke the instroke and outstroke Unit 3.1, 3.2 – Double Acting Cylinder and 5 Port Valve Double Acting Cylinder Draw and label the double acting cylinder and circuit diagram symbol. Label the ‘+’ (extended) and ‘ ‐ ’ (retracted) states. The piston is extended when ………………………………………………… The piston retracts when …………………………………………..………. and is pushed back by …………………………………………. Five Port Valve Draw and label the 5 port valve and the circuit diagram symbol. Build and test the following circuits. Double Acting cylinder and 5/2 valve Double Acting cylinder and pilot/pilot 5/2 valve