Numbers
CCEA A-Level Technology and Design 8900
Material Selection and Wood
Metals
Plastics
Composite and Emerging Materials
Processing Materials
Product Analysis and Design Communication
Design for Manufacture, Quality and Safety
Electronic Control SystemsOption A
Topic overviewControl systems, feedback and electronics safetyResistors, Ohm's law and power ratingsCapacitors and RC timingPotential dividers, sensors and comparatorsSwitches, pull-up and pull-down resistorsOutput devices and LEDsTransistors, Darlington pairs and thyristorsLogic gates, truth tables and flip-flops555 monostable and astable timers
Microelectronic Control SystemsOption A
Topic overviewMicrocontroller systems, ADCs and DACsStrain gauges and bridge circuitsOptical switches, encoded discs and Schmitt triggersOp-amp amplifiers and gainZener diodes and voltage regulatorsKarnaugh maps and binary countersSeven-segment, LCD and dot matrix displaysPIC flowcharts and programmingDC motors, stepper motors and driver circuits
Mechanical and Pneumatic ComponentsOption B
Topic overviewOpen and closed loop mechanical and pneumatic controlSafe working with compressed air and mechanismsLevers, linkages and momentsGear types and gear trainsPulleys, belts, chains and shaft fixingsCams, cranks and converting motionCompressed air supply and pneumatic valvesCylinders, shuttle valves, restrictors and reservoirsPneumatic circuits for logic, timing and speed control
Mechanical and Pneumatic SystemsOption B
Topic overviewHydraulics, system limitations and plant safetyTorque, work, power and air consumptionVacuum handling, proximity sensors and 5/3 valvesSequential and cascade pneumatic circuitsCam profiles and follower displacement diagramsGear geometry, pulley blocks and ratchetsToggles, treadles, shafts and couplingsFriction, brakes and clutchesBearings, lubrication and seals
Designing and Manufacturing ProductsOption C
Topic overviewResearch, questionnaires and specificationsIdea generation, critiques and computer simulationManufacturing planning and product evaluationCFRP, GRP, Kevlar and tungsten carbideSmart materials, nanotechnology and biophotovoltaicsIsometric, perspective and assembly drawingLaminating, steam bending, cutting and printing processesRisk assessment and product safety lawScales of production, JIT and cell productionQuality assurance, ISO 9001 and continuous improvementDesign influences and intellectual property rights
Product Design in Industry and SocietyOption C
Topic overviewLife-cycle environmental impact and climate changeThe 6Rs, waste and environmental legislationSustainable metals, plastics and degradable polymersProduct life cycles, consumer types and relaunchesCAD, CAM, 3D scanning and quick-change mouldingMarket pull, technology push and market strategyPrice, place and promotionJigs, fixtures and ICT in quality controlDesign for maintenance, inclusion and scale productionRendering, typography and presentationDyson, Baylis, Memphis and Apple
Product Development
Product and System Design and Manufacture
Mechanical and Pneumatic Components
Pulleys, belts, chains and shaft fixings
- 3 things to know
- AS 1 Paper 2
Overview
Pulley velocity ratios with worked examples, vee, flat, round and toothed belts, jockey wheels, chain and sprocket drives, grub screws, keys, splines and cotter pins.
What you need to know
Answer each one before you reveal it.
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Key term
How can a belt drive reverse the direction of rotation?
Key term
Why is a vee belt used on machines such as pillar drills?
Questions from this subtopic
Each one with the model answer underneath.
- 1
A 50 mm driver pulley turning at 1400 rpm drives a 200 mm pulley. Find the velocity ratio and the output speed.
Model answer
The velocity ratio is 4:1 and the driven pulley turns at 350 rpm. VR = 200 ÷ 50 = 4, and 1400 ÷ 4 = 350 rpm.
- 2
A 40 mm pulley drives a 120 mm pulley. A 50 mm pulley on the same shaft drives a 150 mm pulley. The motor turns at 2700 rpm. Find the overall velocity ratio and the output speed.
Model answer
The overall velocity ratio is 9:1 and the output turns at 300 rpm. VR = (120 ÷ 40) × (150 ÷ 50) = 9, and 2700 ÷ 9 = 300 rpm.
- 3
How can a belt drive reverse the direction of rotation?
Model answer
A crossed belt, twisted into a figure of eight, makes the driven pulley turn the opposite way. An open belt keeps both pulleys turning the same way.
- 4
Why is a vee belt used on machines such as pillar drills?
Model answer
A vee belt wedges into the groove of its pulley, which increases its grip. The belt can transmit more power without slipping than a flat belt.
- 5
Where is a flat belt a suitable choice?
Model answer
A flat belt suits fast, lightly loaded drives, including drives over long distances. A flat belt can slip harmlessly if the driven machine jams.
- 6
What is a round belt and where is it used?
Model answer
A round belt has a circular cross-section and runs in a grooved pulley. Round belts suit small, light drives such as sewing machines and models.
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