<P> A retarder is a device used to augment or replace some of the functions of primary friction - based braking systems , usually on heavy vehicles . Retarders serve to slow vehicles , or maintain a steady speed while traveling down a hill , and help prevent the vehicle from `` running away '' by accelerating down the hill . They are not usually capable of bringing vehicles to a standstill , as their effectiveness diminishes as vehicle speed lowers . They are usually used as an additional `` assistance '' to slow vehicles , with the final braking done by a conventional friction braking system . As the friction brake will be used less , particularly at higher speeds , their service life is increased , and since in those vehicles the brakes are air - actuated helps to conserve air pressure too . </P>
<P> A retarder is a device used to augment or replace some of the functions of primary friction - based braking systems , usually on heavy vehicles . Retarders serve to slow vehicles , or maintain a steady speed while traveling down a hill , and help prevent the vehicle from `` running away '' by accelerating down the hill . They are not usually capable of bringing vehicles to a standstill , as their effectiveness diminishes as vehicle speed lowers . They are usually used as an additional `` assistance '' to slow vehicles , with the final braking done by a conventional friction braking system . As the friction brake will be used less , particularly at higher speeds , their service life is increased , and since in those vehicles the brakes are air - actuated helps to conserve air pressure too . </P>
what is a retarder on a semi truck
what is a retarder on a semi truck
a device used to augment or replace some of the functions of primary friction - based braking systems , usually on heavy vehicles
a device used to augment or replace some of the functions of primary friction - based braking systems , usually on heavy vehicles