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Personal and Public Transport
Quick questions on Gear ratios and transmission: HSC Engineering Studies Personal and Public Transport
7short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is single-pair gear ratio?Show answer
For a gear pair with a driver gear and a driven gear:
What is speed and torque relations?Show answer
For an ideal (lossless) gear pair:
What is compound (series) gear trains?Show answer
When several gear pairs are connected in series (engine, gearbox first stage, gearbox final stage, final drive), the overall ratio is the product of the individual ratios:
What is why multiple gears are needed?Show answer
The internal combustion engine produces useful torque only over a narrow speed band (typically 2000 to 5500 rpm for a petrol engine). The wheels need to turn anywhere from zero (at start) to about 1500 rpm (at 130 km/h on standard tyres). The transmission provides the variable reduction so the engine stays in its power band across all road speeds.
What is summing ratios in series?Show answer
Series ratios multiply, they do not add.
What is forgetting drivetrain losses?Show answer
Real gearboxes are 85 to 95 percent efficient. Output torque is slightly less than the ideal calculation.
What is confusing overdrive with high gear?Show answer
Overdrive means . Top gear is the lowest ratio in the gearbox. Both speed up the output relative to the input.
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