A “retarder” is a device, other than a brake, which, when activated by the driver, applies a retarding force to the wheels of a vehicle without the use of friction. A retarder may be installed in or on the engine, exhaust system, drive train, or wheels of a motor vehicle, or an axle or wheels of a towed vehicle. A retarder may operate by altering the valve timing of the engine, by controlling the flow of a circulating fluid, by applying an electromagnetic force, by controlling the release of gases from the exhaust system, or by other means. A retarder may or may not be capable of stopping the vehicle upon which it is installed.

(Added by Stats. 1991, Ch. 648, Sec. 1.)

Terms Used In California Vehicle Code 521

  • axle: is a structure or portion of a structure consisting of one or more shafts, spindles, or bearings in the same vertical transverse plane by means of which, in conjunction with wheels mounted on said shafts, spindles, or bearings, a portion of the weight of a vehicle and its load, if any, is continuously transmitted to the roadway when the vehicle is in motion. See California Vehicle Code 230
  • driver: is a person who drives or is in actual physical control of a vehicle. See California Vehicle Code 305
  • motor vehicle: includes a recreational vehicle as that term is defined in subdivision (a) of §. See California Vehicle Code 415
  • retarder: is a device, other than a brake, which, when activated by the driver, applies a retarding force to the wheels of a vehicle without the use of friction. See California Vehicle Code 521
  • vehicle: is a device by which any person or property may be propelled, moved, or drawn upon a highway, excepting a device moved exclusively by human power or used exclusively upon stationary rails or tracks. See California Vehicle Code 670
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