Technical term for a mechanical brake, such as on a vehicle or machine. In everyday speech, ブレーキ is more common.
この機械には安全のための制動機が付いている。
This machine is equipped with a brake for safety.
air brake
Compound of 制動 (braking) and 機 (machine). The exact historical derivation is uncertain, but the term follows standard Sino-Japanese word formation.