Limiter (noun)

1. A device that limits or restricts something, especially the upper or lower limit of an electrical or mechanical system.
2. Something that restricts or controls the extent, amount, or degree of something.
3. A component in an electrical circuit that prevents an excessive voltage or current.

Origin:

Mid 19th century: from limit + -er.

Examples:

1. The speed limiter on the car prevented it from going over the maximum speed limit.
2. The limiter on the amplifier prevented the speaker from being damaged by high volume.
3. The fuel limiter in the airplane helped to prevent overconsumption during flight.
4. The budget limiter required the team to stick to a strict financial plan.
5. The time limiter forced the contestants to work efficiently and complete the task within the allotted time.