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Northern IrelandTechnology and Design

A2 1 Mechanical and Pneumatic Control Systems

6 dot points across 6 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do ratchets, clutches and intermittent mechanisms control and direct motion?

Ratchet and pawl, clutches and brakes, the Geneva mechanism and intermittent motion, and screw threads for converting rotary to linear motion.
A CCEA A-Level Technology and Design answer on advanced mechanisms - the ratchet and pawl for one-way motion, clutches and brakes for engaging and stopping drives, the Geneva mechanism for intermittent motion, and screw threads converting rotary to linear motion.
11 min answer →

How are work, power and efficiency calculated for mechanical systems, and where is energy lost?

Work, power, torque and efficiency in mechanical systems, and the relationship between mechanical advantage, velocity ratio and efficiency.
A CCEA A-Level Technology and Design answer on work, power, torque and efficiency in mechanical systems, and how efficiency relates mechanical advantage to velocity ratio, with the sources of energy loss such as friction.
12 min answer →

How are pneumatic logic and control valves combined to control a cylinder?

Pneumatic logic (AND, OR via shuttle and two-pressure valves), pilot operation, and controlling a cylinder with directional control valves.
A CCEA A-Level Technology and Design answer on pneumatic logic - the AND (two-pressure) and OR (shuttle) valves - pilot-operated directional control valves, and how they are combined to control single- and double-acting cylinders.
12 min answer →

How are pneumatic time delays and automatic sequences of cylinders created?

The pneumatic time-delay circuit (reservoir and restrictor), flow-control of cylinder speed, and sequencing cylinders with limit valves.
A CCEA A-Level Technology and Design answer on the pneumatic time-delay circuit using a flow restrictor and reservoir, controlling cylinder speed with flow-control valves, and sequencing two or more cylinders automatically using limit valves.
12 min answer →

How do we quantify how a material responds to load through stress, strain and the modulus?

Stress, strain, the Young modulus, the stress-strain graph, elastic and plastic behaviour, and factor of safety.
A CCEA A-Level Technology and Design answer on calculating stress and strain, the Young modulus, reading the stress-strain graph (elastic limit, yield, ultimate strength), elastic and plastic behaviour, and applying a factor of safety.
12 min answer →

How do structures carry loads through ties and struts, and how are members made stable?

Structural members in tension and compression (ties and struts), triangulation, beams and the forces in simple frameworks.
A CCEA A-Level Technology and Design answer on how structures carry loads, the difference between ties (tension) and struts (compression), triangulation for stability, beams and bending, and resolving the forces in a simple framework.
12 min answer →