How do pulley, belt and chain drives transmit rotary motion and change speed?
Belt and pulley drives, the velocity ratio from pulley diameters, chain and sprocket drives, and pulley systems for lifting.
A CCEA A-Level Technology and Design answer on belt and pulley drives, calculating the velocity ratio from pulley diameters, chain and sprocket drives, and the mechanical advantage of pulley lifting systems.
Reviewed by: AI editorial process; not yet individually human-reviewed
Have a quick question? Jump to the Q&A page
Jump to a section
What this dot point is asking
CCEA expects you to analyse belt-and-pulley and chain-and-sprocket drives, calculate the velocity ratio from pulley diameters (or sprocket teeth) and the output speed, compare belt and chain drives, and understand pulley systems for lifting. Velocity-ratio calculations are common.
The answer
Belt and pulley drives
Velocity ratio and output speed
Chain drives and lifting pulleys
Worked example: a belt drive and a lifting block
Examples in context
Example 1. Pillar drill. Stepped pulleys and a belt let the operator change the spindle speed by moving the belt to different-diameter pulleys, a direct use of velocity ratio to set speed.
Example 2. Crane block and tackle. A multi-fall pulley block lets a small winch lift a heavy load, the mechanical advantage equalling the number of supporting rope sections, as analysed above.
Try this
Q1. A 30 mm driver pulley drives a 90 mm driven pulley. State the velocity ratio. [1 mark]
- Cue. (3:1).
Q2. Give one advantage of a chain drive over a belt drive. [1 mark]
- Cue. It does not slip, giving a positive, exact drive that can transmit more power.
Q3. A block and tackle has 5 rope sections supporting a 500 N load. Find the ideal effort. [2 marks]
- Cue. (MA = number of supporting falls = 5).
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA 20186 marksA motor pulley of diameter 40 mm drives a belt connected to a pulley of diameter 120 mm on a machine spindle. The motor runs at 1500 rev/min. Calculate the velocity ratio and the spindle speed, and state one advantage of a belt drive.Show worked answer →
For a belt-and-pulley drive the velocity ratio (VR) is the ratio of the driven (output) pulley diameter to the driver (input) pulley diameter:
The spindle (output) speed is the input speed divided by the velocity ratio:
So the spindle turns at 500 rev/min (slower, with more torque).
An advantage of a belt drive: it runs quietly and smoothly, needs little maintenance/lubrication, is cheap, and the belt can slip to protect the machine if it jams (acting as a safety/overload feature); it also tolerates some misalignment.
Markers reward VR = driven/driver diameter = 3:1, output speed = 500 rev/min, and a valid belt-drive advantage.
CCEA 20214 marksState two differences between a belt drive and a chain drive, and give a product that uses a chain drive.Show worked answer →
Two differences:
- Slip: a belt can slip on its pulleys (which can be a disadvantage for accuracy but a useful overload protection), whereas a chain meshes with toothed sprockets and does not slip, so it gives a positive, exact drive and can transmit more power.
- Speed/maintenance: a belt runs quietly with little maintenance, while a chain is noisier, needs lubrication and can stretch/wear, but handles higher loads and torque.
A product using a chain drive: a bicycle (or a motorcycle, or a timing chain in a car engine).
Markers want two valid contrasts (especially slip vs positive drive) and a correct chain-drive example.
Related dot points
- The four types of motion (linear, rotary, reciprocating, oscillating) and the role of mechanisms in changing the type, direction or magnitude of motion and force.
A CCEA A-Level Technology and Design answer on the four types of motion - linear, rotary, reciprocating and oscillating - and how mechanisms change the type, direction or magnitude of motion and force.
- The three classes of lever, the principle of moments, mechanical advantage, and linkages (reverse-motion, bell-crank, parallel).
A CCEA A-Level Technology and Design answer on the three classes of lever, the principle of moments, calculating mechanical advantage and velocity ratio, and common linkages such as reverse-motion, bell-crank and parallel linkages.
- Spur, idler, compound, bevel and worm gears, the gear ratio, and the trade-off between speed and torque.
A CCEA A-Level Technology and Design answer on gear types - spur, idler, compound, bevel and worm - calculating the gear ratio from tooth numbers, and the trade-off between output speed and torque.
- Cams and followers, cam profiles (pear, circular/eccentric, heart-shaped/snail), dwell, rise and fall, and crank-and-slider mechanisms.
A CCEA A-Level Technology and Design answer on cams and followers, common cam profiles (pear, circular/eccentric, heart-shaped), the meaning of dwell, rise and fall, follower types, and the crank-and-slider mechanism for rotary-to-reciprocating conversion.
- Pneumatic components: single- and double-acting cylinders, control valves (3/2 and 5/2), and calculating the thrust of a cylinder.
A CCEA A-Level Technology and Design answer on pneumatic systems, single- and double-acting cylinders, 3/2 and 5/2 control valves, and calculating the output force (thrust) of a cylinder from air pressure and piston area.
Sources & how we know this
- CCEA GCE Technology and Design specification — CCEA (2016)