Gear trains: ratios, torque, and speed

What you’ll practice

Gear trains look simple until compound stages, idlers, and direction changes appear in the same problem. This quiz helps you translate gear layouts into clear speed and torque relationships.

Expect a mix of quick ratio checks and multi-step train calculations, including output direction and the effect of intermediate gears.

Quiz format and difficulty

Each question has 4 options and there’s no timer, so you can calculate carefully and learn from patterns. Choose your question count and difficulty before you start—short sets are great for drilling, while longer runs build consistency across mixed topics.

To keep things fair, the difficulty is balanced by blending straightforward single-mesh items with compound and multi-stage trains, so you’ll see both confidence-builders and stretch questions.

Common pitfalls to avoid

• Treating idler gears as changing the ratio (they usually only change direction)
• Mixing up driver vs driven when computing speed ratios
• Forgetting to multiply ratios across stages in compound trains
• Confusing torque increase with speed increase (they trade off)
• Dropping the sign/direction of rotation when an odd/even number of meshes matters

Tips to improve faster

Write ratios as fractions (output/input) consistently, then apply the same convention to every stage. When stuck, label each gear with angular speed symbols and step through meshes one at a time to avoid sign and inversion errors.