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Ra
Re
Ri
Ro
Ru
Rack-and-pinion
steering A steering system with a pinion gear on the end
of the steering shaft that mates with a rack (think of a geared wheel
opened up and laid flat). When the steering wheel is turned, the
pinion turns, moving the rack to the left or right. This movement is
transmitted through the track rods to the steering arms at the wheels.
Radial
Ply A tire in which the fabric cords run radically in a
line from the wheel hub or straight out from the bead or around the
tubular shape of the tire. Annular belts of fabric or steel mesh add
rigidity. Advantages of this design are: more flexible side walls
with a relatively stiff tread area and a larger and more consistent
footprint on the road under all driving conditions.
Radial
Tires In radials tires the ply or ply cords are aligned at 90
degrees to the circumference. While radials improve performance the
fact is that they are not very good for bad roads and overloading.
The suspension of a vehicle has, also, to be modified to accept
radials. Radials offer much better grip of the road especially on
surfaces which offer poor wheel traction like wet of slippery roads.
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Radiator
The
radiator is used to dissipate the heat that the coolant has absorbed
from the engine. It is constructed to hold a large amount of water in
tubes or passages which provide a large area in contact with the
atmosphere. It generally consists of a radiator core, with its water-carrying
tubes and large cooling area, |
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which
are connected to a receiving tank (end cap) at the top and to a
dispensing tank at the bottom. Side flow radiators have their
"end caps" on the sides, which allows a lower hood line.
While in operation, water is pumped from the engine to the top
(receiving) tank, where it spreads over the tops of the tubes. As the
water passes down through the tubes, it loses its heat to the
airstream, which passes around the outside of the tubes. To help
spread the heated water over the top of all the tubes, a baffle plate
is often placed in the upper tank, directly under the inlet hose from
the engine. Sooner or later, almost everyone has to deal with an
overheating car. Since water is readily available, it is not beyond
the ability of most people to add some to their radiator if it's low.
Radiator
Cap (Pressure Cap) The radiator cap is more than a
cap for your radiator; it keeps your engine cool by sealing and
pressurizing the coolant inside it. It is designed to hold the
coolant in the radiator under a predetermined amount of pressure. If
it was not kept under pressure, it would begin to boil, and soon all
the coolant would have boiled away. However, the radiator (or
pressure) cap prevents this from happening by exerting enough
pressure to keep the coolant from boiling. If your cooling system is
under too much pressure, it can "blow its top"! To prevent
this, the radiator cap has a pressure relief valve. The valve has a
preset rating that allows it to take just up to a certain amount of
pressure. When you turn the cap on the filler neck of the radiator,
you seal the upper and lower sealing surfaces of the filler neck. The
pressure relief valve spring is compressed against the lower seal
when you lock the cap. The radiator filler neck has an overflow tube
right between the two sealing surfaces. If the pressure in the
cooling system exceeds the preset rating of your cap, its pressure
relief valve allows the lower seal to be lifted from its seat. Then
the excess pressure (coolant, air) can squish through the overflow
tube to the ground or the coolant reservoir. Once enough pressure has
been released (the caps preset rating), the pressure relief valve is
again closed by the spring. The pressure cap can be tested with a
cooling system pressure tester, using an adapter, to make certain
that it is living up to its pressure rating. It should be replaced if
it fails the test. It should be noted that most radiator pressure
caps are not meant to be removed, and that the coolant should always
be added through the expansion (overflow) tank. If you happen to
remove the radiator cap from a hot engine, the pressure can cause
steam to shoot out and seriously burn you.
Radiator
Grille The radiator grille is the part of the body shell on the
front of your car that covers the area where the air enters. The
radiator grille can also be part of the bumper on some cars. The
radiator is connected to the shroud for the radiator, which directs
the air that comes in through the radiator grille to the radiator
only. This prevents the air from escaping around the radiator and
failing to cool the engine. On newer cars, the radiator grille has
been lowered to take advantage of lower hood lines, brought about by
an effort to increase fuel efficiency. Older cars had massive
grilles, whereas the cars now produced have smaller more aerodynamic grilles.
Radiator
Shroud The radiator shroud prevents the recirculation of air
around the fan. It is usually a plastic hood that encloses the fan to
guide the air through the core, and stop it from coming back around
and through the fan again. It also protects you from the fan blades!
Rear
Axle
Rear-Axle
See front-axle
and rear-axle split and twist-beam
rear axle
Rear
Axle Crossmember A tubular frame member at the rear of
the body shell that incorporates the mounting points for the rear
axle, e.g., on the VW Beetle and the Porsche 911
Rear
Axle Differential A differential situated in the
final drive of the transmission assembly in a conventional rear-wheel
drive vehicle
Rear
Axle Housing See below banjo
type and split
type.
Rear
Axle Housing, banjo type A rear axle housing from
which the differential unit may be removed while the housing remains
in place on the vehicle. The housing is solid from side to side.
Rear
Axle Housing, split type A rear axle housing made
up of several pieces and bolted together. The housing must be split
apart to remove the differential.
Rear
Axle Ratio The number of times the rear wheels turn
compared to a particular transmission speed. The higher the rear axle
ratio, the slower the engine can run and still allow the vehicle to
achieve a given speed.
Also
called "Final axle ratio."
Rear-Axle Split
Rear
Axle Split See front-axle
and rear-axle split
Rear Bulkhead
The vertical panel across the width of the car that extends behind
the rear seat backrest and separates the interior from the trunk
Rear
Bumper Skirt A rear bumper with integral skirt; a large plastic molding
Rear
Cabin Pillar See C-pillar
Rear
Corner Panel: The bottom corner of the rear fenders. For
manufacturing reasons, often a separate panel
Rear
Corner Valance The bottom corner of the rear fenders. For
manufacturing reasons, often a separate panel
Rear
Deck The surface of the rear of a sedan which includes the lid
of the trunk
Rear
Deck Panel The sheet metal panel extending from the bottom
of the rear window to the rear panel and enclosing the cutout for the
trunk lid, extending sideways to the top of both rear fenders. In
some cases, this panel covers only the area between the bottom of the
rear window and the front edge of the trunk lid
Rear
Differential A differential situated in the final drive of
the transmission assembly in a conventional rear-wheel drive vehicle
Rear
End The rear part of the body shell, extending
approximately from the rear seat pan to the rear apron of the car,
incorporating the trunk floor
Rear
End Lift The tendency of the back of a speeding vehicle
to rise, reducing traction. It can be counteracted by a spoiler
Rear
Engine An engine located at the rear of a vehicle but outside
the wheelbase (i.e., behind the rear wheels). Compare front engine
and mid-engine car
Rear
Fender The body panel which partially encloses a rear wheel
Rear
Fog Lamp A red light with the same intensity as a brake light
Rear
Fog Light A red light with the same intensity as a brake light
rear
head restraints: (rhr) head rests located on the back passenger seats
rear-hinged
door: A older type of door construction that had the hinges at the
rear of the door so that the opening was toward the front (i.e.,
opposite to modern car doors)
rear
lamp cluster: A group of lights at the rear corners of a vehicle,
commonly comprising: tail lamp, brake lamp, back-up lamp, rear fog
lamp, reflector, and signal light
rear
light surround: A separate panel spot-welded at the juncture between
the trailing edge of the rear fender and the rear valance to provide
a mounting base for the rear lights
rear
license plate lamp: A white light illuminating the rear license plate
rear
license plate light: A white light illuminating the rear license plate
rear
panel: A British term for back panel
rear
quarter valance: See rear corner valance
rear
seat belt: An inertia reel belt attached at each end of the rear
seats; a passenger riding in the middle of the rear seats must be
satisfied with just a lap belt, which many safety experts regard as
inadequate. Some manufacturers (notably those from Scandinavia) are
tackling the somewhat costly problem and providing secure lap and
shoulder belts for all passengers riding in the rear seats
rear
seats: See folding rear seats, split folding rear seats, and split
rear seats
rear
sets: Racing-style footrests mounted toward the rear of the machine
to allow the rider to adopt a racing crouch
rear
shelf: The interior shelf extending over the trunk at the level of
the top of the rear seats
rear
side window: One of several types of side body glass: the side
window between the B-posts and C-posts of two-door sedans and coupes,
the rearmost side window of station wagons between the C-post and
D-post, i.e., behind the rear seat backrest, and the third side
window found on some four-door sedans behind the rear side doors
rear
spoiler: An aerofoil mounted on the rear deck or trunk, typically
made of shock-resistant polyurethane with paintable matt black
finish. It is effective only at high speeds, but frequently used for
the sake of appearance. Most sports cars are equipped with front and
rear spoilers (air dams and rear spoilers) to improve the aerodynamic
performance by reduced lifting force
rear
suspension: The axles, springs, and linkages which control the
movement of the rear wheels. Also see five-link rear suspension, four-link
rear suspension, independent rear suspension, multi-link independent
rear suspension, and multi-link rear suspension
rear
tack strip: A fixed or hinged bar on a convertible top which holds
the rear end of the hood against the rear deck
rear
triangle: A bicycle frame triangle formed by the chainstays,
seatstays, and the seat tube.
rear
valance: A separate panel set below the rear panel which extends
approximately from behind the rear bumper downward to protect the
rear end from splashes of mud. In designs with a single-piece rear
panel that incorporates the rear valance, the whole area is sometimes
referred to as the rear valance or rear panel
rearview
mirror: An interior mirror which allows the driver to see behind him.
rear
wash/wipe system: An electrical system for cleaning the rear window,
comprising a water pump, reservoir, and wiper
rear-wheel
drive: (RWD) A configuration in which the rear wheels of the vehicle
are driven
rear-wheel
drive transaxle: A rear-wheel drive construction incorporating a
transmission-differential unit placed between the rear wheels of a
front-engined car. The engine may be a front engine (as in most cars
and all trucks), a mid-engine (as in some sports and racing cars), or
a rear engine (as in some city cars, VW Beetle, the Porsche 911
series, and most buses); RWD ensures good acceleration without
wheelspin even on cars with powerful engines; on most small cars, RWD
has been superseded by front-wheel drive
rear
wheel skirt: See fender skirt
rear
wheel spat: British term for fender skirt
rear
window: The central window at the rear of a vehicle. Although the
American term is backlight, most Americans still call it the rear
window or back window. Also see heated rear window
rear
window heater system: A heating element that removes the fog, mist,
or even ice from the inside and outside of the rear window (i.e., backlight)
rear
window heating: See rear window heater system
rear
window louvres: A plastic molding attached to the rear window which
deflects sun rays to keep the interior cool; usually hinged to lift
up for easy window cleaning
rear
wiper: A window wiper that cleans the rear window
Rear
End Tunnel The rear end tunnel provides clearance for the drive
shaft and the housing of the differential. It allows the rear end to
travel up and down with suspension motion; it clears the differential
housing by a maximum of three or four inches when the suspension is
fully compressed. Often forming the front of the trunk floor, it is
attached to the wheel wells on each side as well as the floor pan and
the trunk floor.
Rearview
Mirror An
interior mirror which allows the driver to see behind him.
Rear
Wash Wipe System An electrical system for cleaning the
rear window, comprising a water pump, reservoir, and wiper.
Rear
Wheel Drive (Rear-Wheel drive)
(RWD)
A configuration in which the rear wheels of the vehicle are driven.
Rear
Wheel Drive Transaxle (rear-wheel drive transaxle)
A
rear-wheel drive construction incorporating a transmission-differential
unit placed between the rear wheels of a front-engined car. The
engine may be a front engine (as in most cars and all trucks), a
mid-engine (as in some sports and racing cars), or a rear engine (as
in some city cars, VW Beetle, the Porsche 911 series, and most
buses); RWD ensures good acceleration without wheelspin even on cars
with powerful engines; on most small cars, RWD has been superseded by
front-wheel drive.
Refrigerant
Any substance used as a heat transfer agent in an air-conditioning
system. R-12 has been the principle refrigerant for many years;
recently, however, manufacturers have begun using R-134a, a non-CFC
substance that is considered less harmful to the ozone in the upper atmosphere.
Resonator
A small auxiliary muffler that assists the main muffler in reducing
exhaust noise.
Reverse-flow
Muffler The reverse-flow has multiple pipes, and is used to
lessen the noise made from an automobile. Four chambers and a double
jacket are used to accomplish muffling of the exhaust noise. Exhaust
gases are directed to the third chamber, forced forward to the first
chamber, from where they travel the length of the muffler and are
exhausted into the tail pipe.
Rich
An
air/fuel mixture that has more petrol than normal. The opposite is lean.
Rich
Air Fuel Mixture (rich air-fuel mixture)
A
mixture of air and fuel in which there is less air and more fuel.
See air-fuel ratio.
Rich
Mixture
A
mixture of air and fuel in which there is less air and more fuel.
See air-fuel ratio. The opposite is lean mixture. Also compare
stoichiometric ratio. A slightly rich mixture generates the maximum
achievable engine power, an overly rich mixture causes spark plug
fouling, loss of engine power, and excessive fuel consumption. Any
rich mixture increases exhaust emissions.
Ring
Gear One of the gears in the rear axle that transmits
power to the differential from the drive shaft.
Rocker
Arm A lever arm that rocks on a shaft or pivots on a stud.
In an overhead valve engine, the rocker arm converts the upward
movement of the pushrod into a downward movement to open a valve.
Roller
Bearings They are used in wheel bearing applications. They
consist of
1.
An inner "race" which is a hardened ring that is slightly
tapered on the outside and
2.
An outer race, a hardened ring that is slightly tapered on the
inside and
3.
A set of rollers contained in a cage. These bearings must not be
crushed together, (the angle of assembly drives them together)
creating friction if they are tightened too far. Roller bearings need
to be repacked periodically with fresh grease to insure a long life.
Rotor
In a distributor, the rotating device inside the cap that connects
the centre electrode and the outer terminals as it turns,
distributing the high voltage from the coil secondary winding to the
proper spark plug. Also, that part of an alternator which rotates
inside the stator. Also, the rotating assembly of a turbocharger,
including the compressor wheel, shaft and turbine wheel.
Rotary
Engine The rotary engine applies power directly to the
transmission. Its construction allows it to provide the power of a
conventional engine that is twice its size and weight and that has
twice as many parts. A large combustion chamber in the form of a
pinched oval, called an epitrochoid is the basic unit of the rotary
engine. Within this chamber all four functions of a piston take place
simultaneously in the three pockets that are formed between the rotor
and the chamber wall. Just as the addition of cylinders increases the
horsepower of a piston-powered engine, so the addition of combustion
chambers increases the power of a rotary engine. Larger cars may
eventually use rotaries with three or four rotors.
Rotary
Valve The "rotary valve" is the key to the operation
of power steering. It directs the power steering fluid under pressure
to either side of the rack piston, which converts hydraulic power to
mechanical force. Friction from the wheel causes a torsion bar in the
rotary valve to deflect. This changes the position of the valve spool
and sleeve, directing fluid under pressure to the proper end of the
power cylinder. The difference in pressure on either side of the
piston (which is attached to the rack) helps move the rack to
reduce turning effort
Runout
The amount of wobble (in-and-out movement) of a gear or wheel as it's
rotated. The amount a shaft rotates "out-of-true." The
out-of-round condition of a rotating part.
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