Quick questions on Gear ratios and transmission: HSC Engineering Studies Personal and Public Transport

3short 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?

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For a gear pair with a driver gear and a driven gear:

What are compound (series) gear trains?

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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 are matching the engine to road conditions?

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The transmission exists because the engine and the road have different needs. The engine produces useful torque only over a narrow band of speed, yet the wheels must turn from zero at a standstill to high speed at cruise. A low gear (high numerical ratio) trades road speed for tractive force, which is what is needed to launch the vehicle and climb hills. A high gear (overdrive, ratio below one) trades force for speed, letting the engine idle along economically at cruising speed.

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