- R
-
- Letter designation for tires to indicate that they are Radial as in P185R13 tire.
- Reverse.
- A letter on a fuel gauge indicating low fuel; when first illuminated it indicates that there is approximately five liters left in reserve.
- Symbol for Resistance
Also see
- R-11
- (trichloromonofluoromethane) Low pressure, synthetic chemical refrigerant which is also used as a cleaning fluid.
- R-22
- (monochlorodifluoromethane) Low temperature refrigerant with boiling point of -40.5°C at atmospheric pressure.
- R-717
- (ammonia) Popular refrigerant for industrial refrigerating systems; also a popular absorption system refrigerant.
- Race
-
Bearing Race
- The inner or outer ring that provides a contact surface for the balls or Rollers in a bearing.
- A competition (usually based on Speed) between two vehicles.
- To run an engine at high speed when not in gear.
- Race cam
- A type of camshaft for race car engines which increases lift of valve, speed of valve opening and closing, length of time valve is held open, etc. Also called Full cam, Three-quarter cam, or Semi-race cam, depending upon design.
- Race camshaft
- A Camshaft, other than stock,
designed to improve
engine performance by altering Cam
profile. Provides
increased lift, faster opening and closing, earlier opening and later closing,
etc. Race camshafts
are available as semi-race or street grind,
Three-quarter race
camshaft or full race.
Grinds in between these general categories are also available.
Also see
- Racing start
- A start on a normal street, e.g., at traffic lights, using excessive throttle resulting in wheelspin and screeching tires.
- Rack
-
- A long, toothed bar.
- Removable wood or metal wall sections attachable to flatbed trailers to make sides for confining loads.
- Rack and pinion gearbox
-
A type of Steering system with a Pinion gear on the end of the Steering shaft. The pinion engages a long rack (a bar with a row of teeth cut along one edge). When the Steering wheel is turned, the pinion turns and moves the rack to the left or right. This movement is carried through Tie rods to the Steering arms at the wheels.
Rack and pinion gearbox
- Rack and pinion steering
-
The pinion gear rotates with the steering shaft, moving the rack from side to side. Several full turns of the pinion are required to shift the rack from lock to lock. Because there are so few parts in the steering linkage, rack and pinion is a very precise and responsive steering system and is often used in sports cars.
Rack and pinion steering
Also see
- Rad
- Abbreviation for Radiator.
- RAD
- Acronym for radiator temperature switch
- Radar detector
- A device which will sense the presence of a radar device which law enforcement officers might be using to spot speeders.
- Radial bearing
- A bearing designed to absorb the radial forces acting on a pump. Compare Thrust bearing
- Radial commutator
- Electrical contact surface on a rotor which is perpendicular or at right angles to the shaft center line.
- Radial compressor
- A compressor with pistons radiating out from the centerline of the compressor. The Harrison (Frigidaire) is a typical example.
- Radial cracking
- Cracking of sidewall rubber running perpendicular to the tire beads. May result from underinflation or exposure to ozone.
- Radial discharge nozzle
- Booster venturi with four spokes or arms which carry fuel to the outer circumference of the booster before discharging it from tiny holes in the ends of the spokes. Used only on the Corvair Model H carburetor.
- Radial engine
-
An internal combustion engine with a number of Cylinders arranged in a circle around the Crankshaft center line. As the crankshaft turns, the pistons are in various stages of the strokes (i.e., intake, exhaust, compression, power). A design often used for aircraft engines.
Radial Engine
- Radial-flow pump
-
An end-suction centrifugal pump with the liquid flowing perpendicular to the pump shaft. The liquid enters at the center of the impeller and is directed out along the impeller blades in a direction at right angles to the pump shaft.
Radial-flow pump
- Radial ply
-
The ply or plies used in tire in which the cords run at right angles to the bead and parallel to the tire radius.
Radial ply
Also see
- Radial ply tire
- A type of tire construction in which sidewall structural plies run radially out towards the tread instead of criss-cross diagonally. With their thinner, more flexible sidewalls, radial tires have lower rolling resistance than cross-ply tires (yielding better fuel consumption) as well as giving longer tread life. They can accommodate the use of low inflation pressures without overheating, due to their flexible sidewalls, but are sometimes more prone to sidewall damage when operating in rocky or stony conditions. Because radial tires invariably also have a braced tread area of great dimensional stability, they "track-lay" the tread (like a bulldozer), do not suffer from "tread shuffle" and so achieve more traction in limiting off-road conditions.
- Radial runout
-
- A tire assembly that does not form a true circle; the radii of the circle are not equal. Most usual causes are bent wheel (out of round) or tire not mounted properly (beads not seated). This is one of the main causes of vehicle vibration.
- A variation in the diameter of a brake disc, wheel, or tire from a specified amount.
- Radial shaft seal
- A typical seal design used to prevent leaks between stationary parts and rotating shafts and to exclude foreign matter. A lip seal, typically of neoprene, is held in a metal retainer and applies a sealing pressure to a rotating shaft, the pressure being provided by an annular garter spring winch surrounds the sealing lip; radial shaft seals are used wherever a shaft penetrates a casing, such as on crankshafts, camshafts, water pump shafts, etc.
- Radial tire
-
A type of tire construction which has the main carcass Plies or cords which run at right angles to the bead and parallel to the radius. By itself, this construction is very weak because when the Bias angle is smaller, the structure is stiff. However, the radial tire has a very large Bias angle. In order to strengthen the tire, a belt surrounds the circumference. This belt is made of low-angle plies (usually about 15 degrees). In this way, the Tread area is stiff and the Sidewalls are flexible. In this way the sidewalls can act independently of each other. In a P185/80R13 tire, R indicates a radial tire.
Radial tire
Also see
- Radiant barrier
- A thin, reflective foil sheet that exhibits low radiant energy transmission and under certain conditions can block radiant heat transfer; installed in attics to reduce heat flow through a roof assembly into the living space.
- Radiant heating
- Heating system in which warm or hot surfaces are used to radiate heat into the space to be conditioned.
- Radiation
-
- The transfer of heat from one object to another when the hotter object sends out invisible rays or waves that upon striking the colder object, cause it to vibrate and thus heat.
- The process by which energy (such as heat) is emitted by one body, as particles or waves, transmitted through an intervening medium or space (like air), and absorbed by another body. Also refers to the energy transferred by this process
- The transfer of heat through matter or space by means of electromagnetic waves.
- Radiation shield
- A separate panel or panels interposed between surfaces and jackets to reduce heat losses through radiation.
- Radiative forcing
- A change in average net radiation at the top of the troposphere (known as the tropopause) because of a change in either incoming solar or exiting infrared radiation. A positive radiative forcing tends on average to warm the earth's surface; a negative radiative forcing on average tends to cool the earth's surface. Greenhouse gases, when emitted into the atmosphere, trap infrared energy radiated from the earth's surface and therefore tend to produce positive radiative forcing.
Also see
- Radiatively active gases
- Gases that absorb incoming solar radiation or outgoing infrared radiation, affecting the vertical temperature profile of the atmosphere.
Also see
- Radiator
-
A device that cools the liquid in the Cooling system by allowing it to circulate through a series of water Channels, which are exposed to air Ducts.
Radiator
- Radiator cap
-
Pressure cap
- A Pressure cap at the top of the radiator.
- A high pressure cap used in radiators to allow operation at high temperature. Higher pressure raises the boiling point of the coolant.
- Radiator drain cock
-
A radiator tap; unlike the Radiator drain plug, tools are not required to drain the coolant from a radiator with a drain cock.
Radiator drain cock
- Radiator drain plug
- A threaded closure plug located at the underside of a radiator used to drain the coolant; usually equipped with a hex or Allen head.
- Radiator fan
- Two types are used on automobiles a crankshaft-driven fan connected by a temperature-sensitive viscous coupling, or a fan driven by an electric motor.
- Radiator fan motor
- An electrically operated motor responsible for driving the radiator fan. An electric motor allows much more freedom in radiator location and engine bay design and permits aftercooling of the engine with the engine switched off most engines mounted crosswise at the front (as on most front-wheel-drive subcompacts) use electric radiator fans which also lead to reduced power losses, since the vehicle's engine is not also required to drive the radiator fan also. The problem with them, however, is that even with the engine off, the fan may start up unexpectedly for the person inspecting the engine bay.
- Radiator fill hole
- An opening at the top of the Radiator through which new water and Coolant can be added when the engine and radiator is cool. In modern vehicles, an overflow reservoir is the location for topping off the radiator fluid since opening a hot radiator cap can be dangerous. The Pressure cap seals the fill hole.
- Radiator grille surround
- The sheet metal panel for mounting the radiator grille; often combined with the front apron to form a single front panel.
- Radiator hose shark tooth pliers
- A special automotive tool for removing and installing radiator and heater hoses; round and toothed jaws securely grip the hose while the handles provide leverage to twist the hose free.
- Radiator overflow tank
-
A small bottle that acts as a reservoir for liquid expelled from the Cooling system through the Overflow pipe and returns the liquid to the system when it cools down. A special Radiator Pressure cap is also part of the kit. It is also called a Closed Cooling System when it is part of the Original equipment.
Radiator overflow tank
- Radiator shell
-
A metal or plastic enclosure which surrounds the outside perimeter of the radiator and mounts to the frame of the vehicle. In modern motorcycles, it is usually chromed.
Radiator shell
- Radiator support panel
- A panel located behind the radiator grille surround which provides a mounting for the radiator and connects the mudguard skirts at their front edge.
- Radiator tank
- A reservoir containing the coolant in a radiator. Early units were made from sheet metal, typically brass or aluminum. Newer versions used advanced polymer technology and injection molding processes have made it possible to produce radiator tanks from thermoplastics. Since all modern cars use forced circulation systems, there is no need for a vertical flow through the radiator. Thus most radiators are mounted horizontally. Also called Radiator Overflow Tank
- Radii adapter
- A mounting device that is used to center a drum or rotor on the arbor of a lathe. A radii adapter centers the drum or rotor through contact with the bearing races.
- Radio
- A device which receives radio signals (either AM, FM, or both) and plays the sound through the speakers. Automobile radios began to appear in vehicles in 1928. Even in the mid-1960s, many cars came without radios.
- Radio choke
- An electric coil used to prevent static in the radio caused by opening and closing of the contact points in the instrument voltage regulator.
- Radio Data System
- (RDS) A system which interrupts a radio broadcast with the latest information on e.g., traffic problems.
- Radio frequency interference
- (RFI) interference generated by the ignition system and other electrical apparatus; counteracted by suppressors.
- Radiograph
- A photograph obtained by passing X-rays or gamma rays through the object to be photographed and recording the variations in density on a photographic film.
- Radius arm
- An additional suspension link in a beam axle layout providing fore-and-aft location of the axle.
- Radius rod
- An additional suspension link in a beam axle layout providing fore-and-aft location of the axle.
- Radius rods
- Rods or arms which are part of the Suspension, usually a live rear axle. They are attached to the axle and pivoted on the Frame. They are used to keep the axle at right angles to the Frame (i.e., prevent lateral movement) and yet permit an up and down motion. On some cars like the Triumph Spitfire, they are used to help locate the Swing axles.
- Radon
- A naturally occurring radioactive gas found in the United States in nearly all types of soil, rock, and water. It can migrate into most buildings. Studies have linked high concentrations of radon to lung cancer.
- Ragtop
- Colloquial term for Convertible.
- Rail job
- A vehicle that has been transformed into a dragster built around a long pipe frame with minimal body panels.
- Railton
- A vehicle brand of which the 1925-1948 models, with required application, are classic cars.
- A model of automobile manufactured by Buick Division of General Motors from 2004-07
- Raising
- The action of beating a rounded shape out of a flat panel by starting in the center and working outward in a spiral to the edge; the metal is shrunk around the edge but remains about the same in the center.
- Raked
- A vehicle which has the Ground clearance or body altered so that either the front or rear of the vehicle is increased or lowered, thus giving the vehicle a tilted appearance.
- Rake the leaves
- Trucker slang for the last vehicle in a string as in "Looks like I get to rake the leaves tonight."
- RAM
- Acronym for Random Access Memory -- memory that serves as a temporary storage place for data from the sensors.
- Ram air
-
- In a ram air system, carburetors get fresh air to be mixed with the gasoline via forward facing ducts. The idea is that as the vehicle moves faster, more air is forced or rammed into the carburetors resulting in improved performance.
- A term referring to the air forced through the condenser coils by vehicle movement or fan action.
- Ram induction
- Using the forward Momentum of vehicle to scoop air and force it into Carburetor via a suitable passageway.
- Ram intake manifold
- An Intake manifold that has very long passageways that at certain Speeds aid the entrance of fuel mixture into the Cylinders.
- Ramp
-
- Equipment used to support a vehicle's front or rear for underbody work.
- A device used to raise a vehicle in the air.
Also see
- Ramp angle
- A measure of vehicle under-belly clearance or the ability to drive over a sharp ridge or ramp without touching the underside of the vehicle on the obstacle. The ramp angle is the angle measured from the lowest part of the chassis at mid-wheelbase down to the periphery of front and rear wheels. Obviously a short wheelbase vehicle with large wheels will have the smallest ramp angle and best under-belly clearance.
- Ramp-over angle
- An indication of how high a hump the vehicle can negotiate without scraping the undercarriage or becoming high-centered; that is, stuck with the center of the vehicle on the hump and the wheels in the air.
- Ram pressure
- The pressure generated by the deflection of the fluid flow due to the curvature of the stator blades, resulting in a momentum acting on the turbine.
- Ram tube
- A tube of a specific length and shape in the intake manifold that promotes performance at certain engine speeds by ramming air into the cylinders.
- Random access memory
- (RAM) A type of volatile memory that is used to store information for either short
or long term usage. This type of memory can be written to. If energy is removed from
the RAM device, the contents in memory are destroyed.
Also see
- Randonnée
- A long bicycle touring ride of 160 to 1200 kilometers made up of several controls (checkpoints).
- Randonneur 5000
- One of the most prestigious awards a Randonneur can earn. To be one of the recipients, a randonneur must do a full series of 200, 300, 400, 600, and 1000km Brevets, a Paris-Brest-Paris randonneur event, a Flèche team ride, and the remaining distances ridden on sanctioned brevets for a total of 5000 kilometers. The qualifying events must all be completed within a four-year period.
- Randonneuring
- Long distance bicycle riding within a specified length of time. First developed in France in 1891 a few years before the Tour de France which later spun off from randonneuring. It is not considered a race but a ride. Everyone who completes the ride within the time limit is awarded the same medal regardless of how quickly he/she rides the distance.
- Randonneurs Mondiaux
- An umbrella organization of national randonneuring groups. Its primary functions are to organize foreign (i.e., France, Spain, United Kingdom, Holland, Belgium, Australia, Denmark, Sweden, Norway, Finland, Austria, Germany, Russia, South Africa, Canada, and the United States) participation in Paris-Brest-Paris and other 1200-kilometer Brevets, encourage the exchange of information of interest to randonneurs, and reward clubs' and individuals' participation in long-distance randonnées with various medals and trophies.
- Rankine cycle
- The thermodynamic cycle that is an ideal standard for comparing performance of heat-engines, steam power plants, steam turbines, and heat pump systems that use a condensable vapor as the working fluid. Efficiency is measured as work done divided by sensible heat supplied.
- Rankine cycle engine
- The Rankine cycle system uses a liquid that evaporates when heated and expands to produce work, such as turning a turbine, which when connected to a generator, produces electricity. The exhaust vapor expelled from the turbine condenses and the liquid is pumped back to the boiler to repeat the cycle. The working fluid most commonly used is water, though other liquids can also be used. Rankine cycle design is used by most commercial electric power plants. The traditional steam locomotive is also a common form of the Rankine cycle engine. The Rankine engine itself can be either a piston engine or a turbine.
- Rasp
-
- A tool like a file with coarse teeth used to prepare a tire for Section repair and for Buffing prior to Retreading.
- The action of using a rasp tool.
- Ratchet
-
- A feature of a special wrench which allows you to turn the handle in one direction to tighten a nut or bolt, but turning it in the opposite direction does nothing but position the handle back where you started and leaves the wrench on the nut or bolt. Likewise you could set the wrench to loosen a nut or bolt.
- A drive handle with ratchet mechanism, usually called a Socket wrench.
- A toothed Rack or wheel which is engaged by a lever to permit motion in only one direction.
Also see
- Ratchet adapter
- A device which converts a torque wrench or drive handle without a ratchet mechanism into a reversible ratchet tool.
- Ratchet handle
- A Ratchet tool.
- Rated capacity
- The quantity of electricity which can be drawn from a fully charged battery for
20 hours by a constant discharging current until cutoff voltage of 1.75 volts per
cell is reached.
Also see
- Rated power
-
- The power output of an engine as horsepower or kilowatt.
- The value stated on the generator nameplate. It is the power available at the output terminals of a component or piece of equipment that is operated in compliance with the manufacturer's performance specifications.
- Rated voltage
- The voltage given for electrical equipment or devices which refers to specified operating conditions.
- Ratio
- A fixed relationship between things in number, quantity or degree.
For example, if the fuel
mixture contains one part of gas for fifteen parts of air, the ratio would be
15 to 1.
Also see
- Air-fuel ratio
- Air ratio
- Aspect ratio
- Axial Ratio
- Bore-stroke ratio
- Braking ratio
- Breeding Ratio
- Bypass Ratio
- Compression ratio
- Economy ratio
- Equivalence Ratio
- Final drive ratio
- Fuel-air ratio
- Gear ratio
- Overall gear ratio
- Oxygen-To-Carbon Ratio
- Pedal Ratio
- Power-to-weight ratio
- Primary compression ratio
- Rear axle ratio
- Seasonal Energy Efficiency Ratio
- Speed ratio
- Stall torque ratio
- Steam-To-Carbon Ratio
- Steering overall ratio
- Steering ratio
- Stoichiometric ratio
- Rationalization
- An industrial reorganization primarily aimed at a more cost-effective and time-saving production process.
- Rat-tail file
- A Round file.
- Rattrap
- The type of Bicycle pedals that have thin metal plates with jagged edges running parallel on each side of the pedal Spindle.
- RAVE valve
- A device used on Two-stroke engines which automatically alters or varies the Exhaust port size. It stands for Rotax adjustable variable exhaust.
- Ravigneaux planetary gear set
- A system which is composed of two sun gears of different diameters, one internal gear, and several planet pinions.
- Raw exhaust gas
- The exhaust gas upstream of any emission control device, e.g., before it passes through a catalytic converter.
- Rayleigh frequency distribution
- A mathematical representation of the frequency or ratio that specific wind speeds occur within a specified time interval.
- Raymond-Mays
- A vehicle brand of which the 1925-1948 models with required application are classic cars.