Glossary of Truck Accidents Terms
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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
style.
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 retarders.
RFG (Reformulated Gasoline): Gasoline blended
with pollution reducing additives.
RoadRailer: Semitrailer specially designed to
travel both on highway and on rails. Manufactured by
Wabash Corp.
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.
