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Q Quarter Panel A sheet metal panel that covers the area from the rear-door opening to the taillight area, and from the bottom of the surface to the base of the roof, or from the headlamp area to the front-door opening, and from the bottom of the surface to the base of the hood. Quartz Halogen Headlamps A headlamp bulb having a quartz envelope holding the tungsten filament and filled with an inert gas containing iodine or another of the five halogen gases. The gas serves to remove the tungsten deposits from the bulb wall and redeposit them on the filament, preventing blackening of the bulb surface and reduction of light output. This kind of cycle requires very high filament operation temperatures which necessitates the use of quartz instead of glass. These lamps produce more lighting power per watt of electrical power than standard sealed beam headlamps.
R 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.
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 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. 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. Ring Gear One of the gears in the rear axle that transmits power to the differential from the drive shaft.
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.
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.
S SAE Acronym for the Society of Automotive Engineers. A professional organization that sets standards for measuring horsepower and torque and for many automotive products such as fasteners, lenses, and lubricants. Sealant A liquid or paste used to prevent leakage at a joint. Sometimes used in conjunction with a gasket. Sealed Beam Lamp An older headlight design which integrates the reflector, lens and filaments into a hermetically-sealed one-piece unit. When a filament burns out or the lens cracks, the entire unit is simply replaced.
Shim Thin spacer, commonly used to adjust the clearance or relative positions between two parts. For example, shims inserted into or under bucket tappets control valve clearances. Clearance is adjusted by changing the thickness of the shim.
Shock Absorber Struts A strut is a structural piece designed to resist pressure in the direction of its length. On typical "McPherson Strut" use, the shock absorber is built into the strut. Most shock absorber struts are hydraulic units. Like the hydraulic shock struts, faulty units must be replaced as an assembly. Another similar front suspension system is called the "hydraulic shock strut." This strut serves as a shock absorber and replaces the upper control arm. The coil spring, however, is located between the lower control arm and the body structure instead of being mounted directly on the strut. Side Beam The operating principle of direct-acting hydraulic shock absorbers is in forcing fluid through restricting openings in the valves. This restricted flow serves to slow down and control rapid movement in the car springs as they react to road irregularities. Usually, fluid flow through the pistons is controlled by spring-loaded valves and the hydraulic shock absorber automatically adapts to the severity of the shock. If the axle moves slowly, resistance to the flow of fluid will be light. If it is rapid or violent, the resistance is stronger, since more time is required to force fluid through the openings. By these actions and reactions, the shock absorbers permit a soft ride over small bumps and provide firm control over spring action for cushioning large bumps. The double-acting units must be effective in both directions because spring rebound can be almost as violent as the original action that compressed the shock absorber. Sleeve Valve Consists of metal sleeves located between the piston and cylinder wall. When moved up and down, holes in the sleeves coincide with inlet and exhaust parts to provide passage for the gases at the right time. Slide Hammer A special puller that screws into or hooks onto a component such as a shaft or bearing; a heavy sliding handle on the shaft bottoms against the end of the shaft to knock the component free.
The analog speedometer that is used on cars indicates its speed and records the distance the car has traveled. A speedometer is driven by a flexible cable connected to the speedometer pinion in the transmission. Speedometers are calibrated in miles per hour and/or in kilometers. The instrument records the distance traveled in miles or kilometers. That portion of the instrument is known as the odometer. Most odometers record the total distance traveled. Some also record the distance of individual trips. Spoiler A spoiler is a kind of wing that is mounted on the rear of the car in a horizontal position. Its function is to provide high-speed stability. In most cars, the spoiler is purely cosmetic, as a car has to be going over 100 mph to take advantage of the aerodynamics of the spoiler. Some mini-vans also make use of a spoiler, but it's upside down, and angled. This type of a rear spoiler only keeps the rain off the rear window. Springs There are two kinds of springs, leaf springs and coil springs. Springs have life spans that are determined by the number of cycles they can withstand over a certain period of time. If a spring breaks while a car is being driven, the car will suddenly lurch downward. The bottom of the car might be damaged, or you might lose your muffler! Leaf springs are made of individual springs, or plates. If you break one plate of your leaf spring, it won't be noticeable, but your car might begin to lean to one side or the other. Coil springs, if they break, will suddenly drop the front or rear end of your car and impair driving under the normal conditions of full suspension travel. Sprocket A tooth or projection on the periphery of a wheel, shaped to engage with a chain or drivebelt. Commonly used to refer to the sprocket wheel itself. Starter The starter converts electricity to mechanical energy in two stages. Turning on the ignition switch releases a small amount of power from the battery to the solenoid above the starter. This creates a magnetic field that pulls the solenoid plunger forward, forcing the attached shift yoke to move the starter drive so that its pinion gear meshes with the engine's crankshaft flywheel. When the plunger completes its travels, it strikes a contact that permits a greater amount of current to flow from the battery to the starter motor. The motor then spins the drive and turns the meshed gears to provide power to the crankshaft, which prepares each cylinder for ignition. After the engine starts, the ignition key is released to break the starting circuit. The solenoid's magnetic field collapses and the return spring pulls the plunger back, automatically shutting off the starter motor and disengaging the starter drive. When the starter is not in use, the drive unit is retracted so that its pinion is disengaged from the flywheel. As soon as the starter is activated, the forward movement of the solenoid plunger causes the shift yoke to move the drive in the opposite direction and engage the pinion and flywheel. The pinion is locked to its shaft by a clutch that unlocks if the engine starts up and the flywheel begins turning the pinion faster than its normal speed. By allowing the pinion to spin freely for a moment, the clutch protects the motor from damage until the drive is retracted. Starter Circuit The starter circuit is activated when the ignition switch is turned on, thereby opening a second switch in the solenoid, permitting a second flow of electricity from the battery to the starter motor. The engine cranking circuit is made up of a battery, starting motor, ignition switch, and electrical wiring. On placing the ignition switch in the "start" position, the solenoid windings are energized and the resulting shift lever movement causes the drive pinion gear to engage the flywheel ring gear, and cranking takes place. When the engine starts, an overrunning clutch (part of the drive assembly) protects the armature from too much speed until the switch is opened. At this time, a return spring causes the pinion gear to disengage from the flywheel. Starter Inhibitor Switch On vehicles with an automatic transmission, a switch that prevents starting if the vehicle is not in Neutral or Park. Steering Arms The steering arms pick up motion from the relay rods and the tie rods, causing the steering knuckles to turn the wheels. They are not used in rack-and-pinion setups. Steering Systems The manual steering system incorporates: 1. steering wheel and column, 2. a manual gearbox and pitman arm or a rack and pinion assembly, 3. linkages; steering knuckles and ball joints; and the wheel spindle assemblies. Power steering systems add a hydraulic pump; fluid reservoir; hoses; lines; and either a power assist unit mounted on, or integral with, a power steering gear assembly. There are several different manual steering gears in current use. The "rack and pinion" type is the choice of most manufacturers. Stroke The back-and-forth motion of the piston. The length of the motion of the piston from top dead center to bottom dead center. Strut The main support member in a MacPherson suspension system. The strut also serves as the shock absorber. Supercharger An air compressor fitted to an internal combustion engine to force the fuel-air mixture into the cylinders at a pressure greater than that of the atmosphere. Boosts the power of the engine.
Sway Bar Some cars require stabilizers to steady the chassis against front-end roll and sway on turns. Stabilizers control this centrifugal tendency that forces a rising action on the side toward the inside of the turn. When the car turns and begins to lean over, the sway bar uses the upward force on the outer wheel to lift on the inner wheel, thus keeping the car more level. Swing Axle Type of independent rear suspension using half shafts that have universal joints only at their inboard ends on both sides of the differential. This causes a camber angle change of the wheel with up-and-down wheel movements.
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