Relay (Relay Driving) Common
practice in the less-than-truckload industry, in which one driver takes a truck
for 8 to 10 hours, then turns the truck over to another driver, pony express
Reefer Refrigerated trailer with insulated walls
and a self powered refrigeration unit. Most commonly used for transporting food.
Retarder 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 predominant manufacturer is Jacobs
Vehicle Equipment Co.) Other types of retarders include exhaust retarders,
transmission-mounted hydraulic retarders and axle-mounted electromagnetic
RFG (Reformulated Gasoline) Gasoline blended with
pollution reducing additives. Common in the Milwaukee metro area..
Rider Policy A policy the company might have that
allows someone, not employed by the company, to ride along with you. Typically
limited to certain times of year (April to November) and limited to age of
rider. The Policy might also stipulate the person must be an immediate family
Rolling Radius Tire dimension from center of the
axle to the ground; measured with tire loaded to rated capacity. Used in
calculating geared speed.
RPM (Revolutions Per Minute) Measure of the speed
at which a shaft spins. Most often used to describe engine crankshaft speed.
Indicated by a tachometer.
Runaway Truck Ramp Emergency area adjacent to a
steep downgrade that a heavy truck can steer into after losing braking power.
Usually two or three lanes wide and several hundred feet long, the ramp is a
soft, gravel-filled pathway which absorbs the truck's forward momentum, bringing
it to a safe stop. Depending on the surrounding terrain, the ramp may be level
or run up or down hill.