Windshield Wipers

BEHAVIOR
They wipe back and forth to swish the rain and snow off a viewing
quadrant so you can see the road ahead. Their melodic “wipe wipe
wipe” can lull you to sleep.




HABITAT
Wipers rest (park) at the base of the windshield, like a faithful dog resting at your feet.

HOW IT WORKS
Wipers are powered by an electric motor that turns a worm gear. A worm gear is a spiral of a raised edge wrapped around a metal cylinder, much like a metal screw. Worm gears are fundamentally different from other gears in several ways. They can radically increase the turning power, or torque, which is useful in applications such as windshield wipers where torque is need to push the long wiper across the windshield. 
Also, worm gears can change the direction of rotation. In the windshield wiper the worm gear changes the direction of the motor shaft’s rotation 90 degrees. The worm gear drives a second gear which is connected
to a cam or crank. The cam or crank converts the rotary motion of the motor into the back-and-forth motion of the wipers. Hand-operated rubber wipers were introduced in 1917 by the company that later became Trico, which is today the largest maker of windshield wipers. After World War I, the company introduced wipers powered not by electric motors, but by the vacuum pressure created in the intake manifold of the engine. This arrangement meant that the speed of the wipers was tied directly to the speed of the engine.
Electric motor wipers were introduced in 1926. Wipers for rear windows were added in 1959. Intermittent wipers were invented by engineer Robert Kearns (later sparking a series of lengthy patent infringement suits) and were introduced in 1969 on Ford’s model Mercury.

INTERESTING FACTS
Windshield wipers were invented before windshields were common in cars. In their early years, cars were a fair weather mode of transportation and had no use for wipers. Mary Anderson invented a simple wiper
for streetcar windows in 1903. Anderson lived most of her life in Birmingham, Alabama. But on a trip to New York she noticed how hard it was for a trolley driver to see through the windshield during a rainstorm, and this experience prompted her to invent the wiper. Wipers for headlights were added by Saab in 1970. Now rain-sensing wipers have appeared on luxury cars.




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    • All rights reserved
    Published by Chicago Review Press, Incorporated
    814 North Franklin Street
    Chicago, Illinois 60610
    ISBN: 978-1-55652-812-5
    Printed in the United States of America
    5 4 3 2 1
    Library of Congress Cataloging-in-Publication Data
    Sobey, Edwin J. C., 1948–
    A field guide to automotive technology / Ed Sobey.
    p. cm.
    Includes index.
    ISBN 978-1-55652-812-5
    1. Automobiles—Popular works. 2. Mechanics—Popular works. I. Title.
    TL146.5.S63 2008
    629.2—dc22
    2008046620


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    Windshield

    BEHAVIOR
    Windshields block debris and water from the interior of the car while
    allowing the visibility needed for safe driving.
    HABITAT
    Windshields occupy the space between roof and hood on the front of
    the car and between the roof and trunk along the rear.
    HOW IT WORKS
    Windshields are a sandwich of polyvinyl butyrate (PVB) between two layers of glass. The PVB holds the two layers of glass together without distorting or limiting the optical qualities. This laminate makes the windshield almost shatterproof, so if it’s damaged it won’t launch shards of glass into people. The windshield is glued into the window frame. On motorcycles, the windshield is often made of acrylic plastic instead of glass.
    Windshield glass transmits nearly all visible light and most infrared light while reflecting most ultraviolet light. Thus, you can see out (and in, unless the windows are tinted) and the car heats up when left in the sun. However, you won’t get a sunburn (which is caused by ultraviolet rays) from sunlight passing through the windshield.
    INTERESTING FACTS
    In the United States about 13 million windshields are replaced each year.


    All rights reserved
    Published by Chicago Review Press, Incorporated
    814 North Franklin Street
    Chicago, Illinois 60610
    ISBN: 978-1-55652-812-5
    Printed in the United States of America
    5 4 3 2 1
    Library of Congress Cataloging-in-Publication Data
    Sobey, Edwin J. C., 1948–
    A field guide to automotive technology / Ed Sobey.
    p. cm.
    Includes index.
    ISBN 978-1-55652-812-5
    1. Automobiles—Popular works. 2. Mechanics—Popular works. I. Title.
    TL146.5.S63 2008
    629.2—dc22
    2008046620
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    Spoiler

    BEHAVIOR
    On passenger cars and trucks, the chief purpose of having a spoiler is
    to make the car look cooler. In race cars spoilers (wings) push the rear
    of the car downward to increase the traction to improve both acceleration
    and braking.
    HABITAT
    Spoilers generally are found on the rear of the car body. However, some cars—NASCAR race cars, for example—and trucks have spoilers on their roofs. Less noticeable are spoilers beneath the front of passenger cars.
    HOW IT WORKS
    The word spoilers comes from the idea that the structures disrupt or spoil the natural flow of air over the car. Technically spoilers and wings are different, although they are lumped together here. Wings are aerodynamic devices whose purpose is to move air. In airplanes they push air downward so the plane has lift. In cars, wings are upside down so they push the car down to give it better traction. Race cars have them over the rear or driving wheels to provide better traction.
    NASCAR cars now have safety wings (called spoilers) on the roof to provide downward force when the car is moving backward at high speed. You might wonder why race cars need downward force when moving opposite to the normal direction of driving. NASCAR cars have a tendency to fly when traveling backward after a collision or spin out.
    A car moving backward at high speeds generates so much lift that it lifts off the ground, making it uncontrollable. Roof spoilers apply downward force to reduce the chance of lift-offs after accidents.
    Passenger cars use devices to cover parts of the car to make them more aerodynamic, reducing drag. A belly pan under a car can smooth the air flow and keep it away from uneven surfaces.
    Trucks use spoilers to divert air up and over their trailers. The flat front surface of a trailer presents a large drag surface. The spoiler pushes air up and over this surface. Stylistic spoilers don’t have aerodynamic or wing shapes. They sit on the rear of red sporty cars looking cool.

    All rights reserved
    Published by Chicago Review Press, Incorporated
    814 North Franklin Street
    Chicago, Illinois 60610
    ISBN: 978-1-55652-812-5
    Printed in the United States of America
    5 4 3 2 1
    Library of Congress Cataloging-in-Publication Data
    Sobey, Edwin J. C., 1948–
    A field guide to automotive technology / Ed Sobey.
    p. cm.
    Includes index.
    ISBN 978-1-55652-812-5
    1. Automobiles—Popular works. 2. Mechanics—Popular works. I. Title.
    TL146.5.S63 2008
    629.2—dc22
    2008046620
    0 comments

    License Plate

    BEHAVIOR
    They identify vehicles for law enforcement. They make the connection
    between owner and vehicle so you pay parking fines.
    HABITAT
    In the United States and most other countries, license plates are required to be viewable from the rear. Most are mounted (bolted) to the rear bumper or to the tailgate or trunk lid.
    In some states, front licenses are also required. These are bolted to the front bumper.
    HOW IT WORKS
    License plates identify the registered owner. Each state creates its own coding system for licenses and records vehicle information numbers and other data along with the license plate numbers.
    INTERESTING FACTS
    License plates have been used from the very dawn of the automobile age. New York was the first state to require their use. In the United States the standard size for a plate is 12 by 6 inches. Most license plates are made by prison inmates. License plates are punched out of mile-long coils of 0.027 inch-thick aluminum. The
    aluminum has to be washed and flattened. Plates are not painted; graphic sheets are glued to the plate. The corners are rounded and holes are punched for mounting. The raised numbers and letters that are unique to each plate are stamped into the plate. Prison inmates stamp each plate individually. Then the raised numbers and letters are inked. After that the plates are loaded into an oven to set the ink and adhesive (that holds the graphics).


    All rights reserved
    Published by Chicago Review Press, Incorporated
    814 North Franklin Street
    Chicago, Illinois 60610
    ISBN: 978-1-55652-812-5
    Printed in the United States of America
    5 4 3 2 1
    Library of Congress Cataloging-in-Publication Data
    Sobey, Edwin J. C., 1948–
    A field guide to automotive technology / Ed Sobey.
    p. cm.
    Includes index.
    ISBN 978-1-55652-812-5
    1. Automobiles—Popular works. 2. Mechanics—Popular works. I. Title.
    TL146.5.S63 2008
    629.2—dc22
    2008046620
    0 comments