A Field Guide to Automotive Technology
By Ed Sobey
Chicago Review Press Incorporated Copyright © 2009 Ed Sobey
All rights reserved.
A BRIEF HISTORY OF WHEELED VEHICLE TECHNOLOGY
Why gas-guzzling cars? Why is our transportation dominated by four wheels powered by a gasoline-snorting engine?
People have been using wheels for nearly 6,000 years. The invention of the wheel probably occurred many times in many places and no event of inception was recorded. At first wheels were powered by the people who made them. Hitching animals to move carts started around 4,000 years ago.
Animals work well pulling people and cargo, but have some serious drawbacks. By the 1880s, New York City had to dispose of 15,000 dead horses that had been left in the streets each year. The city was also engaged in the business of collecting and disposing of 20 tons of horse manure every day. Watching a car belch its exhaust may annoy us, but picture following a team of horses clopping down the street soon after they had eaten their oats. There were serious health concerns about the piles of rotting manure left scattered throughout the city and the accompanying flies. People also complained of the din of iron horseshoes hitting the paving; the noise was so loud that people had trouble talking to one another on the streets. Life for the horses wasn't so great either. Life expectancy of a working horse was about four years, and many were mistreated.
The steam engine changed everything. The concept for steam power had been around since the first century — Hero's Engine, called an aeolipile, was a working steam engine but an impractical one. In the 18th century tinkers started applying new technologies of metallurgy to containing and controlling the power of steam. James Watt made a huge contribution by building an improved steam engine with an external condenser. This innovation thrust steam power into the realm of practicable technology.
The first steam vehicle in the United States was a strange device made by inventor Oliver Evans. Evans's contraption, named the Orukter Amphibolos, could run on land or water. It was designed as a motorized river dredge that could travel over land to get to the dredge site. The dredge was probably never used but inspired generations of early American inventors to try steam power.
Steam power for vehicles was popular well into the 20th century. In 1906 driver Fred Marriott set a land speed record of 121 mph in the Rocket, a steam-powered race car. The Rocket set a new record of 132 mph the following year before crashing.
But steam wasn't alone as a power source for vehicles. Scientific discoveries had led to practical applications for electricity, including the electric motor. By the end of the 19th century, car companies were making both steam and electric vehicles. And a few companies were starting to use the newly invented internal combustion engines.
At the start of the 20th century, internal combustion automobiles ran a distant third behind those powered by steam or electric engines. Electric cars especially were safer to use, provided a smoother and quieter ride, and were easier to operate. Industry experts predicted the demise of the gasoline engine as it was noisy and unreliable, and it delivered an uncomfortable ride. The only certainty in the future of vehicle engines seemed to be that people would be driving cars powered by either steam or electricity.
Today, as electric engines are resurging amid the green revolution and fuel-cost consciousness, it's hard to imagine how electric cars lost market share to gasoline. But internal combustion proponents worked steadily to reduce their engines' drawbacks.
Gasoline engines operate in a relatively narrow range of rotational speeds. While this is not a problem for a lawn mower that chomps away at a steady rate, it is a big problem in powering a car from zero to 60 miles per hour. The invention of the transmission (and much later the automatic transmission) made gasoline and diesel engines competitive.
Starting a gasoline engine was a difficult and dangerous job until Charles Kettering's invention of the automatic starter removed that liability. Kettering also invented the electric ignition system, leaded gasoline (now outlawed due to concerns of lead in the environment), four-wheel brakes, and safety glass.
While gasoline-powered cars became easier to operate, steam remained complex. Although a well-run steam car could keep up with both electric and gasoline cars, steam became increasingly more impractical by comparison.
Initially, engine-powered vehicles were toys for the wealthy. Electric and steam-powered cars never broke out of that mold. Electrics were especially expensive to purchase, although they were cheaper to operate than gasoline — the same as today. The companies that made steam and electric cars focused on serving the limited customer base of the rich. Utility took a backseat to class appeal.
When Henry Ford's grand experiment with mass production took shape, the cost of gasoline cars plummeted. He succeeded in his goal to make cars affordable for the working class. Now people could use cars as practical transportation and not just for weekend picnics. By 1917 the race for dominance had been won by gasoline proponents. Although there were some 50,000 electric-powered cars in the United States that year, there were 70 times more gasoline-powered cars.
Ford succeeded because his engineers were successful in solving the problem of production. The 1908 Model T was so successful that Ford had trouble keeping up with demand in his traditional assembly plants. The Model T ran well on the unpaved roads of America and it ran with little need for expert maintenance — which is good, because little was available. Since Ford was selling every car they could manufacture, they focused on increasing production. It took Ford six years to develop the moving assembly line, which was launched in 1914.
The combination of technological innovations and the economic rise of the middle class ushered in the age of the internal combustion machine. Steam and electric vehicles were soon forgotten.
Trucks followed cars by a few years. The Winton Motor Carriage Company made the first in 1898. Unlike cars, trucks caught on slowly. There wasn't a ready market for them. Horse-drawn wagons were far less costly and were more efficient in some industries. In the home delivery of milk, for example, the horse would move down the street independent of the driver who was walking to leave bottles on the front porches of customers. No gasoline-powered truck could operate unattended like a horse-drawn wagon. And although gasoline-powered trucks could travel farther faster, most deliveries were local and horses worked well for those. Also, the largest businesses had the most money invested in the existing technology — horses and the tack they required — and were protective of that investment and resistant to new technology.
The need to haul more heavy goods farther coupled with the addition of the trailer lead to increased sales of trucks. But it was during World War I that trucks proved reliable. Following the war the road systems in the United States and Europe were improved, making trucks even more practical. And each new innovation in engine technology, suspension, and steering made trucks the practical choice.
Today we take gasoline-powered cars and trucks for granted. Some 45 million are built worldwide every year. But is the end in sight? Will other more environmentally friendly engines take its place?
HOW CARS WORK
Explosions! Thousands of explosions every minute of operation power internal combustion engines. Squirt one part of fuel and 15 parts of air into a closed cylinder, add an electric spark, and there will be an explosion.
Explosions are rapid chemical reactions that release tremendous amounts of energy, mostly as heat. The gases created in the explosion expand rapidly, increasing the pressure inside the cylinder and driving a moveable piston down the cylinder.
A crankshaft converts the up and down motion of several pistons into rotary motion that powers the wheels. But to get to the wheels, the kinetic energy must transfer through a transmission that trades engine speed for torque, or turning power, through a series of gears. Moving torque from the transmission to the wheels requires complex mechanical systems that have great variety in design.
Is this all? Not at all. There is much more to how a car works. But this is a start. Now go look at your car — ask yourself what each part does, and if you don't know the answer look it up in the following pages.
ON THE CAR
MUCH OF YOUR CAR'S TECHNOLOGY is hidden beneath the metal and plastic body or hood. But some equipment cannot be hidden or protected inside the car. In some cases designers blend the machines into the car's body so you don't notice them. Others are themselves design elements and some pop out from hidden recesses when needed.
It wiggles in the wind as you drive at highway speeds, showing patterns of standing waves. It also receives the radio signals that bring you news, sports, music, and way too many commercials. As if that weren't enough, it also provides a perch for antenna balls.
On most cars it is the stiff wire that rises vertically from just in front of the windshield on the passenger's side or on the rear fender on the driver's side.
HOW IT WORKS
Antennas are tuned to receive electromagnetic radiation within certain frequency bands. Note their similarity to tiny antenna on old cell phones. (Newer cell phones, operating at even higher frequencies, have smaller antenna that fit inside the hand unit.) AM and FM radio stations broadcast at low frequencies and large antennas are needed to receive those signals at these frequencies.
To transmit an AM signal the ideal antenna is huge. Hence, AM radio stations have very tall towers and long antenna. FM stations, which operate at higher frequencies, need shorter transmit antennas. But both types of stations have transmit antennas many times larger than the antenna on your car. Driving around with a 100-foot-tall antenna just won't work, so the transmitted signals are strong enough that the less than optimum height antenna on your car still receives radio signals.
Radio antennas had been mounted in the cloth roofs of cars until the advent of steel roofs for cars in 1934. The new roofs reflected and blocked radio waves, so engineers experimented with placing antenna elsewhere, eventually settling on the favored location behind the hood.
Antenna, Citizens Band Radio (CB)
Long and lanky, the CB antenna bends and sways as the pickup truck it's attached to accelerates. It pulls radio from the electromagnetic atmosphere and sends back replies: "That's a ten-four, good buddy."
Long CB antennas are often mounted on a bumper to keep them low enough to fit into garages. Shorter CB antennas are mounted on the roof or on side mirrors of trucks.
HOW IT WORKS
In the United States, citizens band radio operates in the band of frequencies around 27 MHz. Within this band of frequencies 40 channels are designated for CB use. CB users can select any of the channels to use. One channel, 16, is reserved for meeting other users and agreeing which other (lower-traffic) channel to use for conversation.
The radio wave at 27 MHz is 11 meters long. To best capture that signal, the antenna needs to be either one half or one quarter of the wavelength. One half of 11 meters would be too long to use on cars and trucks, so the preferred antenna length is one quarter of 11 meters, or 2.7 meters. That is still quite tall, so the antenna is often mounted on the lowest spot possible — the bumper. To protect the car from being scratched by the antenna as it moves, the antenna is often outfitted with a tennis ball that can bounce against the car.
In many cases, the 2.7-meter antenna would still be too long, so a loading coil is inserted into a shortened antenna. The coil improves reception on shorter than quarter-length antenna. A loading coil can be located anywhere along the length of the antenna, but is often near its base.
This GM system is a subscription service that can provide vehicle tracking (for stolen cars), emergency response (notifying authorities of an emergency and its location), and other communications. Newer versions of OnStar automatically contact emergency services if the vehicle is involved in a serious accident. Some systems allow police to shut off the car's engine if it has been reported stolen.
The antenna is usually found on the back of the roof, in the center. It often has a distinctive shark-fin shape, but other shapes are used as well.
HOW IT WORKS
On Star uses cellular telephone systems to communicate. Emergencies are handled out of two call centers operated around the clock: one in Charlotte, North Carolina, and the other in Oshawa, Ontario.
The system has a diagnostic system to sense problems, such as impacts that suggest a collision. When an impact is recorded, the system communicates to the operation centers by cell phone service provided by the three major cell phone companies in the United States.
The service includes a built-in car phone. The driver can make and receive calls without picking up a phone. Calls are made hands-free.
Antenna, Satellite Radio
The advantage of having satellite radio reception is being able to drive completely across the country and never having to change your radio dial. Or being able to listen to every NFL football game regardless of where you are. Satellite radio delivers dozens of music and entertainment channels, plus sports, news, and traffic information nearly everywhere in the United States, including southern Alaska. Television service for backseat viewers will soon be available by satellite radio.
These antennas can take one of several shapes. Most common is a vertical wire sheathed in plastic about a foot long that has a plastic base attached to the car. Another model added after market is a small plastic box with wires that can be fed into the trunk. All are mounted on the roof or other parts high enough to receive signals from overhead.
HOW IT WORKS
The two satellite companies operating in the United States, Sirius and XM Satellite Radio, merged in February 2007. Because the two companies use incompatible technology, they will have redundant equipment and services until they introduce radio receivers that can receive signals from both systems. The combined company has seven satellites in space plus one spare for each of the two technologies.
XM satellites are geostationary, while Sirius satellites are geosynchronous. A geostationary satellite revolves around the Earth at the same rate that the Earth is spinning, so it stays over the same point relative to Earth. These are located above the equator. Geosynchronous satellites return to the same location above Earth at the same time every day. Having multiple geosynchronous satellites allows the radio company to have one above the center of the United States at all times. This reduces the number of repeaters they need on the ground. The spares are kept on hand to replace a satellite should it fail.
In addition to the satellites, there is a network of ground repeaters that fill in the signal in locations that don't have good reception from the satellite. A typical U.S. city might have 20 repeaters. XM operates about 800 repeaters in the United States.
The satellites broadcast (and the repeaters repeat) a signal within the frequency band centered at 12.5 MHz. They broadcast on two carrier waves within the 12.5 MHz band and use four other bands to repeat the signal. A complex system allows one signal to fill in for another.
The visible receivers catch the radio signals from either satellite or ground repeater, filter out unwanted radio signals, and amplify the signal. The second component of the system decodes the radio signals and lowers the frequency of the signals so the car radio can play the songs.
Autopark and Back-Up Proximity Systems
For the parking-impaired (like me), the autopark or self-park drives the car into tight parallel parking spots. They also assist with backing into a parking space. Less sophisticated systems provide distance warnings as the cars backs up.
Some of the electronics are housed in the dashboard, but the controlling computer is mounted inside the trunk. Sensors are mounted in the front and rear bumpers and on the fenders. (Continues...)
Excerpted from A Field Guide to Automotive Technology by Ed Sobey. Copyright © 2009 Ed Sobey. Excerpted by permission of Chicago Review Press Incorporated.
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