Your Cars Electrical SystemWritten by Kevin Schappell
When automotive industry was in its infancy, it used electricity only to ignite fuel inside engine. By late 1920's, electric starter replaced hand crank, electric headlights made acetylene lamps obsolete and braying of electric horn drowned out squeak of hand-squeezed air horn. Today, an automobile requires an elaborate electrical system of circuits just to produce, store, and distribute all electricity it requires simply for everyday operation. The first major component in electrical system is battery. The battery is used to store power for starting, and for running auxiliary devices such as clocks, radios and alarms when engine is off. The next major component is starter motor, which is used to start engine. The third component is a charging device powered by engine, known as alternator. It powers electrical system when car is running, and restores charge within battery. With these basic components, car maintains its supply of electricity. A device called voltage regulator keeps power level stabilized, and fuse box keeps minor problems from becoming major ones. Many different auxiliary electrical devices are used in modern cars, such as: radios, cellular phones, rear window defrosters and electric door locks, as well as a vast array of motors powering everything from moon roof on down. The above information is directly from Auto Insight program, which you can buy online from AutoEducation.com. Common Problems: ·The battery is usually first part of system to wear out. Most batteries last between 3 and 7 years depending on brand and design. Batteries can be fine on minute, and dead next. More on this later. ·Blown fuse: Is one part of electrical system not working like interior lights or dash lights? The first thing to check is fuses. Look for fuse panel under dash, in glove box, or even in engine compartment in some cars. Most fuse boxes will be labeled by circuit. Modern cars use a blade type fuse which is rectangular in shape and transparent. Look for wire, which runs through fuse, and see if it is burned through. Any discoloring of fuse is a good sign fuse has blown. If you have doubts, replace with a new fuse and test system, which is not working. ·Alternator: Does your car start ok, but your headlights dim when idling. It could be a bad alternator. When alternator cannot produce enough electricity to keep electrical systems running and battery will have to be used to take up slack. This will eventually wear down battery and not allow your car to start. Troubleshooting: I don't think there is a tougher system to troubleshoot on your car than charging/starting system. This is due to fact that there are many things that can go wrong and it's tough to test some components without special equipment. Let's go over some possible situations and their possible causes. ·Car won't start, all I hear is a click but engine does not turn. oFirst check all battery cables for corrosion as this will keep power from flowing freely to starting system. If they are dirty, clean with a wire brush and reattach. Apply a light coat of grease to top of terminals to prevent further corrosion. oBattery could not have enough power stored in it to spin engine. This can be caused by a bad cell in battery or from a bad alternator not charging battery when engine is running. If you can get car to a mechanic, have him or her test battery and charging system with a special tester. This tester places a load on battery and can tell condition. They can also check to see if alternator is working to it's full potential. oStarter or solenoid could be bad. If you can not jump start car and all of battery cables are ok then suspect starter.
| | Your Drive Train ExplainedWritten by Kevin Schappell
The drive train serves two functions: it transmits power from engine to drive wheels, and it varies amount of torque. "Power" is rate or speed at which work is performed. "Torque" is turning or twisting force. Multiple ratio gearboxes are necessary because engine delivers its maximum power at certain speeds, or RPM (Rotations Per Minute). In order to use same engine RPM's at different road speeds, it is necessary to change "Gear Ratio" between engine and drive wheels. Just like a bicycle, car has to switch gears in order to move at a wide range of speeds. Unlike your bicycle, car's drivetrain also has to allow you to back up. (Well, you could push it backwards if you ate your Wheaties) There are actually two sets of gears in drive train; transmission and differential. The transmission allows gear ratio to be adjusted, and differential lets drive wheels turn at different speeds. Manual transmissions usually have four or five speeds, and often have "overdrive", which means that output shaft can turn faster than input shaft for fuel economy on highway. Some use an electric clutch and a switch that controls whether overdrive is engaged or not. An interesting development on a few cars is "clutchless" manual transmission, which uses a stick shift and an automatic electric clutch. Speed and position sensors, mini computers, and throttle controls keep engine from over-revving when driver shifts gears. As with many automotive "inventions", this is an old idea, which may now reach feasibility due to computer revolution. Automatic transmissions commonly use three forward gears to blend speed and torque. In case of a three-speed transmission, first gear delivers maximum torque and minimum speed for starting. Second gear offers medium torque and speed for acceleration and hill climbing. Third gear allows maximum speed with minimum torque for highway travel. A reverse gear permits backward movement. A transmission is a speed and power-changing device installed at some point between engine and driving wheels of a vehicle. It provides a means for changing ratio between engine RPM (Revolutions Per Minute) and driving wheel RPM to best meet each particular driving situation. Some types of drive train layouts use a "Transaxle", which is simply a combination of transmission and differential. These are usually found on front wheel drive cars, but are also used on mid- and rear-engine cars. Some exotic cars have their engine in front, and a transaxle in rear of car for better weight balance. Torque is derived from power. The amount of torque obtainable from a source of power is proportional to distance from center of rotation at which it is applied. It is logical, then, that if we have a shaft (in this case, crankshaft) rotating at any given speed, we can put gears of different sizes on shaft and obtain different results. If we put a large gear on shaft, we will get more speed and less power at rim than with a small gear. If we place another shaft parallel to our driving shaft and install gears on it in line with those on driving shaft, we can obtain almost any desired combination of speed or power within limits of engine's ability. That is exactly what an automobile transmission does by means of gears and other devices. There are two types of transmissions; manual and automatic. If you have a manual transmission, you have to shift gears yourself, usually with a stick located on your console and clutch pedal. If you have an automatic transmission, mechanism changes without any help from you. This is accomplished through a system that works by oil pressure. Each shift of gears is controlled by a shift valve; gears shift change depending on speed, road, and load conditions.
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