Aptitude Tests > Mechanical Reasoning Tests > Gears

A gear is a toothed wheel or cylinder that meshes with another toothed component to transmit motion or to change speed or direction. Gears are attached to a rotating shaft turned by an external force, which is not usually illustrated in these types of question. Two gears may be connected by touching each other directly or by means of a chain or belt.

If gears are connected by a chain or belt then they move in the same direction.

If the gears are touching (meshed) then adjacent gears move in opposite directions. In this example the first and third gear will turn in the same direction. When there are an odd number of meshed gears then the last gear will always turn in the same direction as the first one.

Meshed gears with an equal number of teeth will turn at the same speed. If they have an unequal number of teeth then the gear with the fewest teeth will turn faster. To work out how fast one is turning with respect to the other you need to count the teeth.

Example Meshed and Belt Driven Gear Questions

1) If gear X turns clockwise at a constant speed of 10 rpm. How does gear Y turn?

2) If gear X turns clockwise at a constant speed of 10 rpm. How does gear Y turn?

3) If bar Y moves left a constant speed. How does bar X move?

4) If drive wheel X rotates clockwise at a speed of 10 rpm. How does wheel Y turn?

5) If drive wheel X rotates clockwise at a speed of 10 rpm. How does wheel Y turn?

Answers to Questions
1) A
2) D
3) D
4) B
5) E