Device used to assist brakes in slowing the vehicle The most common type of retarder on over-the-road trucks manipulates the engine's valves to create engine drag (This type is commonly referred to as "Jake Brake" because the pred ominant manufacturer is Jacobs Vehicle Equipment Co ) Other types of retarders include exhaust retarders, transmission-mounted hydraulic retarders and axle-mounted electromagnetic retarders
Any of various devices, as a helix of flat metal strip, introduced into a boiler tube to increase the heating effect of the fire