a mechanical device used to reduce the speed of a machine; also called [[减速箱|減速箱|jian3 su4 xiang1]]

A substance used in a nuclear reactor to slow down the speed of neutrons without absorbing them to maintain a chain reaction.

ridge or bar installed across a road surface to force drivers to reduce their speed

a rocket engine that provides thrust in the opposite direction to the motion of a spacecraft, used to slow it down

a mechanical housing or case containing reduction gears used to decrease the output speed of a motor or engine

a raised strip on a roadway surface designed to slow down motor-vehicle traffic

A strip or ridge installed across a roadway to force drivers to slow down; also called [[减速条|減速條|jian3 su4 tiao2]] or [[减速垫|減速墊|jian3 su4 dian4]]