Which type of gear is most likely to experience backlash?

Backlash is a common phenomenon in gears that refers to the play or loose movement between the meshing teeth when the direction of movement changes. In the context of the options provided, spur gears are the most likely to experience backlash due to their design and the way they engage with one another.

Spur gears have straight, parallel teeth that mesh directly. When force is applied in one direction, there is a gap between the teeth of the driving and driven gears when the rotation stops or changes direction. This gap allows for a certain degree of movement before the gears re-engage, resulting in backlash.

In contrast, other types of gears, like worm gears, have a unique configuration where the worm can mesh very tightly with the worm wheel, minimizing any play. Bevel gears often engage at an angle which can also limit the potential for backlash in certain designs. Planetary gears, although they can have a compact design with multiple gears, are typically designed to minimize play due to the nature of their arrangement within a planetary system.

Therefore, the inherent design features of spur gears that allow linear engagement between teeth make them most susceptible to experiencing backlash compared to the other gear types.