Water (Coolant) Jackets

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.

Wheel (Slave) Cylinder

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.

Wheel Lugs

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.

Wheel Well

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.

Wheels

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.

Windshield

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.

Windshield Washers

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.

Windshield Wipers

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.

Wires and Cables

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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