Comment by pjc50

5 years ago

Timing belts have teeth.

Occasionally chains are used instead; more expensive and heavier, but more durable. You do need to maintain the timing either way it it will destroy the valves.

If the engine is a non-interference design, losing the belt won’t be catastrophic for the valves

>Timing belts have teeth.

To expand: It is the teeth that make belts timing belts, they keep the 'timing' (relative rotational orientation) of 2 or more toothed pulleys. In an ICE the camshafts are locked to a 2:1 ratio to the crank shaft, in a 3d printer it keeps an axis fixed relative to the stepper motor shaft.

I think another reason belts are common is that chains tend to be a bit noisier.