Terms Starting with R
R 134a-A hydro fluorocarbon gas that is not damaging to the environment and ozone layer that can be used in air conditioning systems.
Rack-and-pinion steering-A steering system consisting of a flat gear (rack) and a mating gear (pinion). The pinion meshes with teeth on the rack causing the rack to move left or right. This motion moves tie-rods and the spindle arm to steer the front wheels of the vehicle.
Radial-Something that radiates from a center point. Radial tires have cord material running in a direction from the center point of the tire, usually from bead to bead.
Radiation-Transferring heat energy to radiant energy.
RAM-Random access memory, or temporary storage of information in a computer.
Ram air-Air that is forced into the engine or passenger compartment by the force of the vehicle moving forward.
Reciprocating engine-An engine in which combustion pressures move parts up and down, or back and forth.
Rectify-To change one type of voltage to another. For example, ac voltage is rectified to dc voltage in a battery charger.
Refrigerant-A liquid capable of vaporizing at low temperatures, such as ammonia or Freon.
Relay-An electromagnetic device which has low amperage in one circuit to operate a circuit or electrical device with higher amperage. A cooling system relay is used to operate the electric fan.
Reluctor-In an electronic ignition system, a metal wheel with a series of points used to produce the signal for the transistor.
Residual pressure-Remaining or leftover pressure.
Resistance-The part in an electrical circuit called the load.
Resonator-A device used in an exhaust system to reduce noise, usually used in conjunction with the muffler.
Revolutions per minute (rpm)-The number of crankshaft revolutions occurring in an engine each minute.
Rich mixture-Too much fuel and not enough air for efficient combustion in the engine.
Road horsepower-Horsepower available at the drive wheels of the vehicle.
Rocker arm-An arm that has a pivot point in the center. One side is lifted by the camshaft lobe movement and the other side moves down to open the valves.
Rolling resistance-A term used to describe the amount of resistance a tire has as it's rolling on the road. Tires that have lower rolling resistance usually get better fuel mileage. Radial tires have lower rolling resistance.
ROM-Read only memory or permanent storage of information in a computer.
Rope seals-A type of seal used on crankshafts shaped much like a small thin rope to seal oil inside the engine.
RTV sealants-A type of sealant that is able to cure in the presence of moisture and oxygen.
Rust inhibitors-A type of chemical put into cooling and fuel systems to prevent rust from forming in the liquid.
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