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Water (Coolant) Jackets |
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Water Jackets are used in cars to keep them cool. It is a collection of
passages within the block and head, which let the coolant circulate around the
"hot spots" (valve seats and guides, cylinder walls, combustion chamber, etc.)
in order to cool them off. The engine block is actually manufactured in one
piece with the water jackets cast into the block and cylinder head. At normal
operating temperature, the water pump forces the coolant through the head
gasket openings and on into the water jackets in the cylinder head. It flows
around in there, cooling everything off by absorbing the heat. After doing its
thing, the coolant flows through the upper hose to the radiator where it
releases the heat. Then, the water pump sends it back down into the engine's
water jackets to continue the cooling process. On the sides of the engine are
"freeze" or "expansion" plugs, which are sheet metal plugs pressed into a
series of holes in the block, and are designed to hold the pressure of the
cooling system. However, they pop out if the coolant in the block ever freezes.
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Wheel (Slave) Cylinder |
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The wheel cylinder, also called the brake cylinder or slave cylinder, is a
cylinder in which movable piston(s) convert hydraulic fluid pressure into
mechanical force. The piston(s) within the cylinder move the brake shoes or
pads against the braking surface of the drum or rotor. There is one cylinder
(or more in some systems) for each wheel. The cylinder is usually made up of a
single-bore cylinder casting, an internal compression spring, two pistons, two
rubber cups or seals, two rubber boots to prevent entry of dirt and water, and
a bleeder screw (valve). In drum type brakes, the wheel cylinder is fitted with
push rods that extend from the outer side of each piston through a rubber boot,
where they bear against the toe end of each brake shoe. In disc brakes, the
wheel cylinder is part of the caliper. As the brake pedal is depressed, it
moves pistons within the master cylinder, forcing hydraulic brake fluid through
the brake lines and into cylinders at each wheel. The fluid under pressure
causes the wheel cylinders' pistons to move, which forces the shoes or pads
against the brake drums or rotors. Two-way pressure is applied when the wheel
cylinder is activated. Brake fluid enters the center of the cylinder, forcing
the pistons apart. Pushrods at the piston ends then apply equal pressure to the
brake shoes. When pressure is released, a return spring pulls the pistons
together. |
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Wheel Lugs |
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The large bolts that go through the wheel rim and secure it to the wheel hub
are known as the wheel lugs. They are pressed into the hub from the inboard
side so they cannot pull out when tightened. The lug nuts thread onto the wheel
lugs, clamping the wheel rim between the hub and lug nuts. If the wheel lug
nuts are not properly tightened your wheel will come off. Over- tightening,
conversely, can prevent you from being able to change a flat tire. |
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Wheel Well |
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The wheel well is either plastic or metal. Metal wheel wells are usually part
of the body shell. Metal wheel wells strengthen the structure of the car
because of their shape, and because they are strongly welded to the body shell.
Most rear wheel wells are made of metal. Wheel wells are coated with a
rock-proof, rubberized coating underneath to prevent the rocks kicked up by the
wheels from damaging the metal and making a lot of noise when they hit. The
front wheels are often made of plastic. This is because it is harder to mount
the engine with the front wheel wells in place. Plastic wheel wells can be
removed, and are easier to mount the engine during the manufacturing of the
car. |
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Wheels |
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Wheels come in many different designs and usually fall into two categories:
stamped sheet metal and machine castings. Some wheels are a combination of the
two. Generally cast alloy wheels are higher priced, but have greater strength
than stamped sheet metal wheels. The most common are the stamped sheet metal
wheels because they are less expensive to produce and are adequate for most
uses. Some cars have wire wheels, which consist of three basic components;
inner rings, outer rings, and a series of spokes, which connect the two. Cast
aluminum wheels are very popular, magnesium wheels are also popular. Both are
popular because they are lightweight and strong. |
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Windshield |
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Most windshields are stationary. They are fixed in place with a weather-strip
made of rubber, which has a groove on the inside and a groove on the outside.
The inside groove holds the glass; the outside groove holds the metal rim of
the windshield opening in place. The glass "floats" in a plastic sealant that
is spread out between the edge of the glass and the frame of the windshield.
Windshields are made of laminated safety plate glass, which is a sandwich of
glass and clear plastic. The plastic acts as a soft, protective barrier,
keeping the glass in place, if it is struck during a collision. The glass
sticks to the plastic to eliminate glass from flying around the interior and
injuring someone. |
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Windshield Washers |
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All cars use an electric pump-operated windshield washer with a positive
displacement washer pump. On some, the motor is placed in the washer reservoir,
while on others, it is driven by a wiper motor. When the pump is attached to
the wiper motor, the four lobe cam starts a spring-loaded follower, but the
pump does not operate all the time that the wiper motor is running. This is
because the pumping mechanism is locked out and pumping action occurs. |
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Windshield Wipers |
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Most cars have an intermittent wiper system, which permits the driver to select
a delayed wipe that operates only every few seconds. A representative
wiper/washer unit is the wiper assembly, which incorporates a depressed park
system that places the wiper blades below the hood line in the parked position.
The relay control uses a relay coil, relay armature, and switch assembly. It
controls starting and stopping of the wiper through a latching mechanism. An
electric washer pump is mounted on the gear box section of the wiper. The wiper
unit gear assembly drives it. |
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Wires and Cables |
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Wires and cables conduct electricity. Usually, they are made of annealed copper
and are used to carry electricity to the various electrical devices and
equipment on passenger cars and trucks. Wire and cable sizes are expressed by a
gauge number, which indicates the cross-sectional area of the conductor. The
larger the diameter of the wire or cable, the smaller the gauge size number.
Cables are made of several strands of wire. The cross-sectional area is equal
to the circular mil area of a single strand times the number of strands. |
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