Mechanical and Pneumatic Components

What Mechanical and Pneumatic Components covers

Mechanical and Pneumatic Components is examined in Unit AS 1, Paper 2: Option B, Mechanical and Pneumatic Control Systems, one option of three. It covers open and closed loop mechanical and pneumatic control, safe working with compressed air and mechanisms, levers, linkages and moments, gear types and gear trains, pulleys, belts, chains and shaft fixings, cams, cranks and converting motion, compressed air supply and pneumatic valves, cylinders, shuttle valves, restrictors and reservoirs and pneumatic circuits for logic, timing and speed control.

The 9 subtopics

Each one has its own page.

• Open and closed loop mechanical and pneumatic controlInput, control and output in pneumatic circuits, open and closed loop control, feedback from trip valves and float valves, valve symbols and port numbers, and solenoid valves.Open →
• Safe working with compressed air and mechanismsHazards of compressed air, depressurising circuits, rated pressures and relief valves, silencers, eye protection, in-running nips, guards and emergency stops.Open →
• Levers, linkages and momentsMoments and the principle of moments, mechanical advantage, velocity ratio and efficiency with worked levers, the three classes of lever, bell cranks and parallel linkages.Open →
• Gear types and gear trainsSpur, bevel and worm gears, rack and pinion, gear train velocity ratios with worked calculations, idler and compound gears, and the effect of gearing on torque.Open →
• Pulleys, belts, chains and shaft fixingsPulley velocity ratios with worked examples, vee, flat, round and toothed belts, jockey wheels, chain and sprocket drives, grub screws, keys, splines and cotter pins.Open →
• Cams, cranks and converting motionLinear, rotary, oscillating and reciprocating motion, crank and slider, pear, heart, snail, eccentric and plate cams, rise, fall and dwell, and followers.Open →
• Compressed air supply and pneumatic valvesCompressors, receivers and air mains, filter, regulator and lubricator units, 3/2 and 5/2 valves, trip, plunger, solenoid, pilot and diaphragm valves, and valve memory.Open →
• Cylinders, shuttle valves, restrictors and reservoirsSingle-acting and double-acting cylinders, force, pressure and area with worked calculations, shuttle valves, flow restrictors, reservoirs and connecting components.Open →
• Pneumatic circuits for logic, timing and speed controlDirect and indirect control, double-pilot 5/2 circuits, AND, OR and NOT logic, time delays, speed control, air bleed sensors and automatic reciprocation.Open →

What you need to know

Answer each one before you reveal it.

Take Mechanical and Pneumatic Components further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Single-acting cylinder vs Double-acting cylinder

  Single-acting cylinder: a piston unit driven out by air pressure and returned by an internal spring. Double-acting cylinder: a piston unit driven both outwards and back by compressed air.

• Open loop vs Closed loop

  Open loop: a control system that acts without checking its output. Closed loop: a control system that feeds output information back to correct itself.

• Mechanical advantage vs Velocity ratio

  Mechanical advantage: the load divided by the effort. Velocity ratio: the effort distance divided by the load distance.

Questions from this topic

Each one with the model answer underneath.

1. 1

   In a pneumatic circuit that clamps a workpiece, identify the input, control and output components.

   Model answer

   A push-button 3/2 valve is the input. A pilot-operated 5/2 valve is the control stage. A double-acting cylinder is the output that clamps the work.

2. 2

   What is an open loop control system?

   Model answer

   An open loop system acts on its input without checking what the output has done. A cylinder extended by a push button, with nothing confirming it arrived, is open loop.

3. 3

   What is a closed loop control system?

   Model answer

   A closed loop system passes information about its output back to the control stage. The system then corrects itself until the output matches what is wanted.

4. 4

   Define feedback in a control system.

   Model answer

   Feedback is a signal taken from the output and returned to the control stage. The signal lets the system compare what happened with what was wanted.

5. 5

   How does a roller trip valve provide feedback in a pneumatic circuit?

   Model answer

   A roller trip valve at the end of a cylinder's stroke is pressed by the moving piston rod. The valve then signals that the movement is complete and can start the next action.

6. 6

   Explain how the float valve in a water cistern works as a closed loop mechanical system.

   Model answer

   The float senses the water level and lifts a lever arm as the level rises. The lever closes the inlet valve at the set level, so the output controls the input.

What is inside Levo

Six ways to work the same material.

Mechanical and Pneumatic Components revision questions

What does Mechanical and Pneumatic Components cover in CCEA A-Level Technology and Design?

9 subtopics: open and closed loop mechanical and pneumatic control, safe working with compressed air and mechanisms, levers, linkages and moments, gear types and gear trains, pulleys, belts, chains and shaft fixings, cams, cranks and converting motion, compressed air supply and pneumatic valves, cylinders, shuttle valves, restrictors and reservoirs and pneumatic circuits for logic, timing and speed control. Each one has its own page with questions and model answers.

How is Mechanical and Pneumatic Components organised?

By the CCEA 8900 specification, subtopic by subtopic, so it matches the order you are taught it in.