Clutches

Clutches

If you drive a manual transmission car, you may be surprised to find out that it has more than one clutch. And it turns out that folks with automatic transmission cars have clutches, too. In fact, there are clutches in many things you probably see or use every day: Many cordless drills have a clutch, chain saws have a centrifugal clutch and even some yo-yos have a clutch.

Clutches are useful in devices that have two rotating shafts. In these devices, one of the shafts is typically driven by a motor or pulley, and the other shaft drives another device. In a drill, for instance, one shaft is driven by a motor and the other drives a drill chuck. The clutch connects the two shafts so that they can either be locked together and spin at the same speed, or be decoupled and spin at different speeds.

In a car, you need a clutch because the engine spins all the time, but the car's wheels do not. In order for­ a car to stop without killing the engine, the wheels need to be disconnected from the engine somehow. The clutch allows us to smoothly engage a spinning engine to a non-spinning transmission by controlling the slippage between them.
To understand how a clutch works, it helps to know a little bit about friction, which is a measure of how hard it is to slide one object over another.

Friction is caused by the peaks and valleys that are part of every surface -- even very smooth surfaces still have microscopic peaks and valleys. The larger these peaks and valleys are, the harder it is to slide the object.

A clutch works because of friction between a clutch plate and a flywheel.

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Fly Wheels, Clutch Plates and Friction
In a car's clutch, a flywheel connects to the engine, and a clutch plate connects to the transmission. You can see what this looks like in the figure below.

When your foot is off the pedal, the springs push the pressure plate against the clutch disc, which in turn presses against the flywheel. This locks the engine to the transmission input shaft, causing them to spin at the same speed.

The amount of force the clutch can hold depends on the friction between the clutch plate and the flywheel, and how much force the spring puts on the pressure plate.

When the clutch pedal is pressed, a cable or hydraulic piston pushes on the release fork, which presses the throw-out bearing against the middle of the diaphragm spring. As the middle of the diaphragm spring is pushed in, a series of pins near the outside of the spring causes the spring to pull the pressure plate away from the clutch disc .

This releases the clutch from the spinning engine.

Note the springs in the clutch plate. These springs help to isolate the transmission from the shock of the clutch engaging.

This design usually works pretty well, but it does have a few drawbacks.

Common Problems
From the 1950s to the 1970s, you could count on getting between 50,000 and 70,000 miles from your car's clutch. Clutches can now last for more than 80,000 miles if you use them gently and maintain them well. If not cared for, clutches can start to break down at 35,000 miles. Trucks that are consistently overloaded or that frequently tow heavy loads can also have problems with relatively new clutches.
The most common problem with clutches is that the friction material on the disc wears out. The friction material on a clutch disc is very similar to the friction material on the pads of a disc brake or the shoes of a drum brake -- after a while, it wears away. When most or all of the friction material is gone, the clutch will start to slip, and eventually it won't transmit any power from the engine to the wheels.

The clutch only wears while the clutch disc and the flywheel are spinning at different speeds. When they are locked together, the friction material is held tightly against the flywheel, and they spin in sync. It's only when the clutch disc is slipping against the flywheel that wearing occurs. So, if you are the type of driver who slips the clutch a lot, you'll wear out your clutch a lot faster.

Sometimes the problem is not with slipping, but with sticking. If your clutch won't release properly, it will continue to turn the input shaft. This can cause grinding, or completely prevent your car from going into gear. Some common reasons a clutch may stick are:

-Broken or stretched clutch cable - The cable needs the right amount of tension to push and pull effectively.

-Leaky or defective slave and/or master clutch cylinders - Leaks keep the cylinders from building the necessary amount of pressure.

-Air in the hydraulic line - Air affects the hydraulics by taking up space the fluid needs to build pressure.

-Misadjusted linkage - When your foot hits the pedal, the linkage transmits the wrong amount of force.

-Mismatched clutch components - Not all aftermarket parts work with your clutch.

A "hard" clutch is also a common problem. All clutches require some amount of force to depress fully. If you have to press hard on the pedal, there may be something wrong. Sticking or binding in the pedal linkage, cable, cross shaft, or pivot ball are common causes. Sometimes a blockage or worn seals in the hydraulic system can also cause a hard clutch.
Another problem associated with clutches is a worn throw-out bearing, sometimes called a clutch release bearing. This bearing applies force to the fingers of the spinning pressure plate to release the clutch. If you hear a rumbling sound when the clutch engages, you might have a problem with the throw-out.

Clutch Diagnostic Test
If you find that your clutch has failed, here is an at-home diagnostic test that anyone can perform:

1-Start your car, set the parking break, and put the car in neutral.

2-With your car idling, listen for a growling noise without pushing the clutch in. If you hear something, it's most likely a problem with the transmission. If you don't hear a noise, proceed to step three.

3-With the car still in neutral, begin to push the clutch and listen for noise. If you hear a chirping noise as you press, it's most likely the clutch release, or throw-out bearing. If you don't hear a noise, proceed to step four.

4-Push the clutch all the way to the floor. If you hear a squealing noise, it's probably the pilot bearing or bushing.

If you don't hear any noise during these four steps, then your problem is probably not the clutch. If you hear the noise at idle and it goes away when the clutch is pressed, it may be an issue in the contact point between the fork and pivot ball.

Amazing video (inside the engine)

See how the engine is built with it's different parts

Great video (motion of engine)

learn how engine works from inside

Note : it will be useful if you read the (engine post ) befor you watch this video

Differential Unit

The differential has three jobs:
-To aim the engine power at the wheels

-To act as the final gear reduction in the vehicle, slowing the rotational speed of the transmission one final time before it hits the wheels

-To transmit the power to the wheels while allowing them to rotate at different speeds (This is the one that earned the differential its name.)

Why You Need a Differential Car wheels spin at different speeds?, especially when turning. You can see from the animation below that each wheel travels a different distance through the turn, and that the inside wheels travel a shorter distance than the outside wheels. Since speed is equal to the distance traveled divided by the time it takes to go that distance, the wheels that travel a shorter distance travel at a lower speed. Also note that the front wheels travel a different distance than the rear wheels. For the non-driven wheels on your car -- the front wheels on a rear-wheel drive car, the back wheels on a front-wheel drive car -- this is not an issue. There is no connection between them, so they spin independently. But the driven wheels are linked together so that a single engine and transmission can turn both wheels. If your car did not have a differential, the wheels would have to be locked together, forced to spin at the same speed. This would make turning difficult and hard on your car: For the car to be able to turn, one tire would have to slip. With modern tires and concrete roads, a great deal of force is required to make a tire slip. That force would have to be transmitted through the axle from one wheel to another, putting a heavy strain on the axle components.
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What is a Differential?
The differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed.

The differential is found on all modern cars and trucks, and also in many all-wheel-drive (full-time four-wheel-drive) vehicles. These all-wheel-drive vehicles need a differential between each set of drive wheels, and they need one between the front and the back wheels as well, because the front wheels travel a different distance through a turn than the rear wheels.

Part-time four-wheel-drive systems don't have a differential between the front and rear wheels; instead, they are locked together so that the front and rear wheels have to turn at the same average speed. This is why these vehicles are hard to turn on concrete when the four-wheel-drive system is engaged.

Open Differentials
We will start with the simplest type of differential, called an open differential. First we'll need to explore some terminology: The image below labels the components of an open differential

When a car is driving straight down the road, both drive wheels are spinning at the same speed. The input pinion is turning the ring gear and cage, and none of the pinions within the cage are rotating -- both side gears are effectively locked to the cage.

Note that the input pinion is a smaller gear than the ring gear; this is the last gear reduction in the car. You may have heard terms like rear axle ratio or final drive ratio. These refer to the gear ratio in the differential. If the final drive ratio is 4.10, then the ring gear has 4.10 times as many teeth as the input pinion gear.
When a car makes a turn, the wheels must spin at different speeds.

So we can see that the differential is wery important for the carand without it,we wouldn't be able turn the car over the road.

The most powerful car in the world !!!!!!VERON

Bugatti Veron

How would you define the most amazing production car in the world? Would it be:
-The car with the most horsepower?
-The car with the fastest top speed and acceleration?
-The most expensive car?

At the moment, the Bugatti Veyron appears to have it all:
-A W-16 engine that can produce 1,001 horsepower
-A top speed of 250+ mph (400+ kph)
-A zero-to-60 time of three seconds
-A zero-to-180 time of 14 seconds
-A price tag somewhere in the $1.2 million range.

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The Bugatti Veyron is a car built around an engine. Essentially, Bugatti made the decision to blow the doors off the supercar world by creating a 1,000-horsepower engine. Everything else follows from that resolution.

So let's start with the engine. How would you begin the design process for an engine this powerful? If you have read How Car Engines Work, you know that if you want to create a 1,000-horsepower engine, it has to be able to burn enough gasoline to generate 1,000 horsepower. That works out to about 1.33 gallons (5 liters) of gasoline per minute.

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Creating the Engine
Bugatti did two things to create a compact engine capable of producing 1,000 hp.

The first and most obvious thing is turbocharging

If you know How Turbochargers Work, you know that one easy way to make an engine more powerful without making the engine bigger is to stuff more air into the cylinders on each intake stroke. Turbochargers do that. A turbo pressurizes the air coming into the cylinder so the cylinder can hold more air.

If you stuff twice as much air in each cylinder, you can burn twice as much gasoline. In reality, it's not quite a perfect ratio like that, but you get the idea. The Bugatti uses a maximum turbo boost of 18 PSI to double the output power of its engine.

Therefore, turbocharging allows Bugatti to cut the size of the engine from 16 liters back down to a more manageable 8 liters.
To generate that much air pressure, the Bugatti requires four separate turbochargers arranged around the engine.

The second thing Bugatti engineers did, both to keep the RPM redline high and to lower lag time when you press the accelerator, was to double the number of cylinders. The Bugatti has a very rare 16-cylinder engine.
There are two easy ways to create a 16-cylinder engine.
One way would be to put two V-8 engines in-line with each other. You connect the output shaft of the two V-8s together.
Another would be to put two in-line 8-cylinder engines beside one another. The latter technique is, in fact, the way Bugatti created its first 16-cylinder cars in the early 20th century.
For the Veyron, Bugatti chose a much more challenging path. Essentially, Bugatti merged two V-8 engines onto one another, and then let both of them share the same crankshaft. This configuration creates the W-16 engine found in the Veyron. The two V's create a W!!!!!!!!!!!!

Special Features
The special features of the Bugatti W-16 engine are amazing. For example:

-The engine has four valves per cylinder, for a total of 64 valves.

-It has a dry sump lubrication system borrowed from Formula 1 race cars, along with an intricate internal oil path to ensure proper lubrication and cooling within the 16 cylinders.

-It has electronically controlled, continuously variable cam timing to create optimal performance at different engine rpm settings.

-It has a massive radiator to deal with all of the waste heat that burning 1.33 gallons of gasoline per minute can generate. Everything about the engine is superlative.

-And it is remarkably compact. It measures just 710 mm (27 inches) long, 889 mm (35 inches) wide and 730 mm (28.7 inches) high. This is the beauty of Bugatti's W-16 approach -- the engineers managed to fit 1,000 hp into a reasonably sized package.

In order to harness all of this horsepower and torque, you need an amazing transmission...

The Transmission

The transmission is unique, in particular because it has to harness about twice as much torque as any previous sports-car transmission. It has:
-Seven gears
-A dual clutch system
-Sequential shifting
-A paddle-driven, computer-controlled shifting system

This computer-controlled system is identical to the sort of system found in a Formula 1 car or a Champ car. There is no clutch pedal or shift lever for the driver to operate -- the computer controls the clutch disks as well as the actual shifting. The computer is able to shift gears in 0.2 seconds.

It would be almost impossible for all of the torque available from the W-16 engine to flow out to just two wheels without constant wheel-spin. Therefore, the Veyron has full-time all-wheel drive. By applying the engine's power to all four wheels through a computer-controlled traction-control system, the car is able to harness all of the engine's horsepower, even at full acceleration.

The Body
According to one of the Veyron's designers, the biggest challenge in creating the Veyron was the aerodynamics. How do you keep a 250-mph passenger car on the road?

The Veyron's dimensions help to some extent. The car is 79 inches (200 cm) wide, 176 inches (447 cm) long and only 48 inches (122 cm) high. Keep in mind that a Hummer 2 is 81.2 inches wide. The Bugatti is extremely wide for its height.

The underside of the Veyron, like an F-1 car, is streamlined and venturi-shaped to increase downforce. There is also a wing in the back of the Veyron (see below) that extends automatically at high speed to increase downforce and keep the car glued to the road. According to Popular Science: Hypercar, "With the moving tail spoiler we've got enough downforce now, about 100 kg (221 pounds) at the rear and 80 kg (177 pounds) at the front at top speed."

If you look at the above photo, you'll notice two snorkel-like devices, one on either side of the engine, on the roof of the car. The Veyron uses these to manage airflow. The Veyron has three reasons for managing airflow:
At maximum power, the engine is consuming 45,000 liters of air per minute.
At maximum power, the engine is burning 1.33 gallons of gasoline per minute and needs to dissipate all of that heat through its radiators.

When stopping, the brakes need to dissipate heat ?- especially important when rapidly accelerating and braking on twisty road courses.
You can see how the Veyron handles these requirements in the photo below.

The engine of the Veryon sits behind the driver, so roof-mounted snorkels, the rear-deck vents and side-mounted scoops bring air to the engine and rear brakes.

The size of the engine and transmission, along with the four-wheel-drive system and the four drive shafts, along with the opulence of the passenger compartment and the car's oversized dimensions, all add weight. Even though the body is sculpted in carbon fiber to minimize its mass, the car weighs in at about 4,300 pounds (1,950 kg). For comparison, a Dodge Viper weighs about 1,000 pounds (454 kg) less.

The Tires and Interior

Even the tires for the Veyron are unique. They're specially designed by Michelin to handle the stress of driving at 250 mph. The tires need to be sticky like a race car's and able to handle 1.3 G's on the skidpad. However, they also need to last longer than the 70 or so miles of a typical race tire.
Michelin therefore created completely new tires to handle the Veyron's unique requirements. In the rear, the tires are 14.4 inches (36.6 cm) wide. Specifically, the tires measure 245/690 R 520 A front and 365/710 R 540 A rear, where 245 and 365 are the width in millimeters (9.5 and 14.4 inches respectively). The rims are 520 mm and 540 mm in diameter (approximately 20 inches). These tires, in other words, are massive -- the rears are the widest ever produced for a passenger car.
The tires use the Michelin PAX system. Their pressure is monitored automatically, and they can run flat for approximately 125 miles (201 km) at 50 mph (80 kph). According to Michelin, the run-flat detection system "plays an integral role in active safety in PAX System. Its role is to inform you of a loss of pressure, either gradual or sudden." Once warned of an air leak by the PAX system, you can reduce your speed and head toward a tire repair center.
One advantage of the PAX system and its run-flat ability is that it eliminates the need for a spare tire

The Interior

The Veyron seats two in lavish style. The interior is swathed almost completely in leather -- the dash, seats, floor and sides are all leather. Only the instruments and a few metal trim pieces interrupt the leather experience.

The car also surrounds its occupants with every sort of electronic nicety, including a remarkable stereo system, navigation system, etc.

Is all of this worth a million bucks? Who knows. But regardless, the Veyron represents a remarkable technological achievement.

The Veyron is also likely to represent the far end of the automotive performance spectrum for some time to come. To create a car much faster will require adding even more weight, and delivering even more power to the wheels. The added weight means diminishing returns in the power-to-weight domain. Additional power means more wheelspin.

Look at a Champ car and consider how radical its appearance is compared to a passenger car. Consider also that a Champ car does not go much faster than the Veyron. The Veyron probably approaches the outer limits of the passenger car envelope, and we are unlikely to see much beyond the Veyron in terms of performance.
This is, in other words, as good as it gets.

Anti-lock brake system

The theory behind anti-lock brakes is simple. A skidding wheel (where the tire contact patch is sliding relative to the road) has less traction than a non-skidding wheel. If you have been stuck on ice, you know that if your wheels are spinning you have no traction. This is because the contact patch is sliding relative to the ice .

By keeping the wheels from skidding while you slow down, anti-lock brakes benefit you in two ways:

-You'll stop faster,

-and you'll be able to steer while you stop.

There are four main components to an ABS system:
-Speed sensors
-Pump
-Valves
-Controller

­Speed Sensors

The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information.

Valves

There is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions:
-In position one, the valve is open; pressure from the master cylinder is passed right through to the brake.

-In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder.

-In position three, the valve releases some of the pressure from the brake.

Pump

Since the valve is able to release pressure from the brakes, there has to be some way to put that pressure back. That is what the pump does; when a valve reduces the pressure in a line, the pump is there to get the pressure back up.
ControllerThe controller is a computer in the car. It watches the speed sensors and controls the valves.

ABS at Work

There are many different variations and control algorithms for ABS systems. We will discuss how one of the simpler systems works.
The controller monitors the speed sensors at all times. It is looking for decelerations in the wheel that are out of the ordinary. Right before a wheel locks up, it will experience a rapid deceleration.

If left unchecked, the wheel would stop much more quickly than any car could. It might take a car five seconds to stop from 60 mph (96.6 kph) under ideal conditions, but a wheel that locks up could stop spinning in less than a second.
The ABS controller knows that such a rapid deceleration is impossible, so it reduces the pressure to that brake until it sees an acceleration, then it increases the pressure until it sees the deceleration again. It can do this very quickly, before the tire can actually significantly change speed. The result is that the tire slows down at the same rate as the car, with the brakes keeping the tires very near the point at which they will start to lock up. This gives the system maximum braking power.

When the ABS system is in operation you will feel a pulsing in the brake pedal; this comes from the rapid opening and closing of the valves. Some ABS systems can cycle up to 15 times per second.

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Anti-Lock Brake Types
­Anti-lock braking systems use different schemes depending on the type of brakes in use. We will refer to them by the number of channels -- that is, how many valves that are individually controlled -- and the number of speed sensors.
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Four-channel,

four-sensor ABSThis is the best scheme. There is a speed sensor on all four wheels and a separate valve for all four wheels. With this setup, the controller monitors each wheel individually to make sure it is achieving maximum braking force.

Three-channel,

three-sensor ABSThis scheme, commonly found on pickup trucks with four-wheel ABS, has a speed sensor and a valve for each of the front wheels, with one valve and one sensor for both rear wheels. The speed sensor for the rear wheels is located in the rear axle.
This sys­tem provides individual control of the front wheels, so they can both achieve maximum braking force. The rear wheels, however, are monitored together; they both have to start to lock up before the ABS will activate on the rear. With this system, it is possible that one of the rear wheels will lock during a stop, reducing brake effectiveness.
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One-channel,

one-sensor ABSThis system is commonly found on pickup trucks with rear-wheel ABS. It has one valve, which controls both rear wheels, and one speed sensor, located in the rear axle.
This system operates the same as the rear end of a three-channel system. The rear wheels are monitored together and they both have to start to lock up before the ABS kicks in. In this system it is also possible that one of the rear wheels will lock, reducing brake effectiveness.
This system is easy to identify. Usually there will be one brake line going through a T-fitting to both rear wheels. You can locate the speed sensor by looking for an electrical connection near the differential on the rear-axle housing.­

ETS (Electronic Traction System)

The problem in accelerating the vechile is that it cause the tires to slip and that gives you low accelerationand cause the tires to lose traction with the ground !!!!!!!!!!!

That's why they invented the the ETS ( Electronic Traction System)

Traction control helps limit tire slip in acceleration on slippery surfaces. In the past, drivers had to feather the gas pedal to prevent the drive wheels from spinning wildly on slippery pavement. Many of today's vehicles employ electronic controls to limit power delivery for the driver, eliminating wheel slip and helping the driver accelerate under control.

Powerful rear-drive cars from the sixties often had a primitive form of traction control called a limited slip rear differential. Sometimes referred to as Positraction, a limited-slip rear axle will mechanically transfer power to the rear wheel with the most traction, helping to reduce, but not eliminate wheel spin. While limited-slip rear axles are still in use in many front- and rear-drive vehicles today, the device can't completely eliminate wheel slip. Hence, a more sophisticated system was needed.

Enter electronic traction control. In modern vehicles, traction-control systems utilize the same wheel-speed sensors employed by the antilock braking system. These sensors measure differences in rotational speed to determine if the wheels that are receiving power have lost traction. When the traction-control system determines that one wheel is spinning more quickly than the others, it automatically "pumps" the brake to that wheel to reduce its speed and lessen wheel slip. In most cases, individual wheel braking is enough to control wheel slip. However, some traction-control systems also reduce engine power to the slipping wheels. On a few of these vehicles, drivers may sense pulsations of the gas pedal when the system is reducing engine power much like a brake pedal pulsates when the antilock braking system is working.

Many people mistakenly believe that traction control will prevent their vehicle from getting stuck in the snow. This couldn't be further from the truth.

In my point of view this is not an exraordenary system because traction control does not have the ability to increase traction; it just attempts to prevent a vehicle's wheels from spinning.

and ander some conditions accelerating more , may cause your car loses traction

Amazing stability system(ESC)

Electronic Stability Control

ESC

During normal driving, ESC works in the background, continuously monitoring steering and vehicle direction. ESC compares the driver's intended direction (by measuring steering angle) to the vehicle's actual direction (by measuring lateral acceleration, vehicle rotation (yaw), and individual road wheel speeds).

ESC only intervenes when it detects loss of steering control, i.e. when the vehicle is not going where the driver is steering.

This may happen, for example, when skidding during emergency evasive swerves, understeer or oversteer during poorly judged turns on slippery roads, or hydroplaning. ESC measures the direction of the skid, and then applies the brakes to individual wheels asymmetrically in order to create torque about the vehicle's vertical axis, opposing the skid and bringing the vehicle back in line with the driver's commanded direction. Additionally, the system may reduce engine power or operate the transmission to slow the vehicle down.

Oversteering

Understeering

ESC can work on any surface, from dry pavement to frozen lakes. It reacte to and corrects skidding much faster and more effectively than the typical human driver, often before the driver is even aware of any imminent loss of control. In fact, this led to some concern that ESC could allow drivers to become overconfident in their vehicle's handling and/or their own driving skills. For this reason, ESC systems typically inform the driver when they intervene, so that the driver knows that the vehicle's handling limits have been approached. Most activate a dashboard indicator light and/or alert tone; some intentionally allow the vehicle's corrected course to deviate very slightly from the driver-commanded direction, even if it is possible to more precisely match it.

Indeed, all ESC manufacturers emphasize that the system is not a performance enhancement nor a replacement for safe driving practices, but rather a safety technology to assist the driver in recovering from dangerous situations. ESC does not increase traction, so it does not enable faster cornering (although it can facilitate better-controlled cornering). More generally, ESC works within inherent limits of the vehicle's handling and available traction between the tires and road. A reckless maneuver can still exceed these limits, resulting in loss of control. For example, in a severe hydroplaning scenario, the wheel(s) that ESC would use to correct a skid may not even initially be in contact with the road, reducing its effectiveness.

In July 2004, on the Crown Majesta, Toyota offered a Vehicle Dynamics Integrated Management (VDIM) system that incorporated formerly independent systems including ESC and worked not only after the skid was detected but also worked to prevent the skid from occurring in the first place. Using electric variable gear ratio steering power steering this more advanced systems could also alter steering gear ratios and steering torque levels to assist the driver in evasive maneuvers.

More you need to know about power and torque

Since we introduced the meaning of torque (review post power and torque)

we need to know about the power !!!!!!!!!

power is the ability of the object to push a mass to a certian speed

so if we have a body builder and he holds a 10 kg weight and runs at 10 km/hr

his power will be p= 100 .N *10= 1000 kg.km/hr

This is the same as the truks it can carry heavy loads but at low speed

and viceversa,

The race car can't carry heavy loads but can run at high speeds

so may be you find a truck has same power as a race car

but this for the torque and that for the speed

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This is a comparison between torque and power

If you have ever tried to loosen really tight lug nuts on your car, you know a good way to make a lot of torque is to position the wrench so that it is horizontal, and then stand on the end of the wrench -- this way you are applying all of your weight at a distance equal to the length of the wrench.

If you were to position the wrench with the handle pointing straight up, and then stand on the top of the handle (assuming you could keep your balance), you would have no chance of loosening the lug nut. You might as well stand directly on the lug nut.

One engine is a turbocharged Caterpillar C-12 diesel truck engine. This engine weighs about 2,000 pounds, and has a displacement of 732 cubic inches (12 liters).

The other engine is a highly modified Ford Mustang Cobra engine, with a displacement of 280 cubic inches (4.6 liters); it has an added supercharger and weighs about 400 pounds. They both produce a maximum of about 430 horsepower (hp), but only one of these engines is suitable for pulling a heavy truck. The reason lies partly in the power/torque curve shown above.
When the animation pauses, you can see that the Caterpillar engine produces 1,650 lb-ft of torque at 1200 rpm, which is 377 hp. At 5,600 rpm, the Mustang engine also makes 377 hp, but it only makes 354 lb-ft of torque. If you have read the article on gear ratios, you might be thinking of a way to help the Mustang engine produce the same 1,650 lb-ft of torque. If you put a gear reduction of 4.66:1 on the Mustang engine, the output speed would be (5,600/4.66 rpm) 1,200 rpm, and the torque would be (4.66 * 354 lb-ft) 1,650 lb-ft -- exactly the same as the big Caterpillar engine.
Now you might be wondering, why don't big trucks use small gas engines instead of big diesel engines? In the scenario above, the big Caterpillar engine is loafing along at 1,200 rpm, nice and slow, producing 377 horsepower. Meanwhile, the small gas engine is screaming along at 5,600 rpm. The small gas engine is not going to last very long at that speed and power output. The big truck engine is designed to last years, and to drive hundreds of thousands of miles each year it lasts.

The Honda

The Honda Accord was introduced way back in 1976 as a 1977 model. It arrived from Japan as a compact two-door hatchback coupe, basically a scaled-up version of the original Honda Civic subcompact. That first Accord immediately impressed critics and buyers alike with its smooth mechanical refinement, pleasant front-wheel-drive road manners, topnotch assembly, and strong features-per-dollar quotient. The world has changed a lot in three decades, yet those traits are still in evidence, one reason why the Accord remains Honda's top-selling passenger car, not to mention one of the most popular cars on the American market. Since 2000, in fact, only the Toyota Camry, its perennial archrival, has outsold the Accord.

The Honda Accord was redesigned for 1982, by which time a four-door sedan had been added. With sales climbing, Honda decided to build American-market Accords in the U.S., starting in 1984, at a brand-new "transplant" factory in Marysville, Ohio. The reasons were political as well as economic, but the venture proved so successful that other import brands would follow Honda's lead. Accord was again redesigned for 1986, becoming longer, lower, more stylish, and somewhat sportier to drive.
The last was no surprise, given Honda's origins as a motorcycle maker, its long-time emphasis on engineering -- and its occasional involvement in auto racing. Accord became still sportier for 1989, when notchback coupe models were added and top-line LXi versions gained a firmer suspension and steering. Even so, the Honda Accord remained firmly focused on family-friendly transportation. Underlining that point was the new fourth-generation design for 1990, which grew to nearly midsize-car dimensions and offered station wagon models instead of hatchbacks.
Since then, the Honda Accord has been redesigned three more times, each generation adding size, power, refinement and new features to the successful formula. That frequent updating helps explain Accord's continued strong appeal. So does a consistent high level of customer satisfaction, not to mention the consistently strong resale values that have come to be associated with the Honda brand.
This article traces the evolution of the Honda Accord from the original 1977 models to the latest 2007 versions. It's divided by the seven design generations that span these model years.
Each section begins with a description of the major design and engineering features for that generation. It then discusses the significant changes to Accord for each model year within the generation.
©2007 Honda via WieckAs evidenced by the 1990 Honda Accord, the model has constantly evolved.
Beginning with the 1990-1993 generation, each section also includes a segment entitled "Honda Accord Reliability." This lists the car's notable trouble spots as reported by owners and mechanics, and includes problems covered in company-issued service bulletins.
In addition, each section starting with the 1990-1993 generation concludes with "Honda Accord Safety Recalls. These are recalls issued by the U.S. government's National Highway Traffic Safety Administration.
The Accord is to Honda what the Camry is Toyota: a popular mainstream car that makes a major contribution to its maker's bottom line -- and public image. Each model has its pluses and minuses, yet are closely matched in design concept, price, market position, and other respects. No wonder they've competed so long to top each year's new-car sales chart. Accord has its faults, of course, as does Camry.

SEE COMING NEXT FOR HONDAS...................

A new generation of tires

For more than 100 years, vehicles have been rolling along on cushions of air encased in rubber. The pneumatic tire has served drivers and passengers well on road and off, but a new design by Michelin could change all that - the Tweel Airless Tire.

Michelin first announced the Tweel in 2005. The name is a combination of the words tire and wheel because the Tweel doesn’t use a traditional wheel hub assembly.

A solid inner hub mounts to the axle. That’s surrounded by polyurethane spokes arrayed in a pattern of wedges. A shear band is stretched across the spokes, forming the outer edge of the tire (the part that comes in contact with the road). The tension of the shear band on the spokes and the strength of the spokes themselves replace the air pressure of a traditional tire. The tread is then attached to the shear band. The Tweel looks sort of like a very large, futuristic bicycle wheel.

When the Tweel is put to the road, the spokes absorb road impacts the same way air pressure does in pneumatic tires. The tread and shear bands deform temporarily as the spokes bend, then quickly spring back into shape. Tweels can be made with different spoke tensions, allowing for different handling characteristics.
More pliant spokes result in a more comfortable ride with improved handling. The lateral stiffness of the Tweel is also adjustable. However, you can’t adjust a Tweel once it has been manufactured. You’ll have to select a different Tweel. For testing, Michelin equipped an Audi A4 with Tweels made with five times as much lateral stiffness as a pneumatic tire, resulting in “very responsive handling” [Source: Michelin].
Michelin reports that “the Tweel prototype… is within five percent of the rolling resistance and mass levels of current pneumatic tires. That translates to mean within one percent of the fue economy” of the tires on your own car. Since the Tweel is very early in its development, Michelin could be expected to improve those numbers.

The Future of Airless Tires
The Tweel does have several flaws (aside from the name). The worst is vibration. Above 50 mph, the Tweel vibrates considerably. That in itself might not be a problem, but it causes two other things: noise and heat. A fast moving Tweel is unpleasantly loud [Source: CBS News]. Long-distance driving at high speeds generates more heat than Michelin engineers would like.

Another problem involves the tire industry. Making Tweels is quite a different process than making a pneumatic tire. The sheer scale of the changes that would need to be made to numerous factories, not to mention tire balancing and mounting equipment in thousands of auto repair shops, presents a significant (though not insurmountable) obstacle to the broad adoption of airless tires.
Because of these flaws, Michelin is not planning to roll out the Tweel to consumers any time soon. “Radial tire technology will continue as the standard for a long time to come,” said Michelin’s press release touting Tweel development. They are initially working on Tweel use in low-speed applications, such as on construction vehicles. The Tweel is perfect for such use because the high-speed vibration problems won’t come into play, and the ruggedness of the airless design will be a major advantage on a construction site. Michelin is also exploring military use of the Tweel.

At a public demonstration of the Tweel, Michelin placed prototypes on the iBOT, a personal mobility device for physically impaired people, and the Segway Centaur, a four-wheeled ATV-type vehicle that uses Segway’s self-balancing technology.

Car Stability

stability
Measure of how difficult it is to move an object from a position of balance or equilibrium with respect to gravity.

An object displaced from equilibrium does not remain in its new position if its weight, acting vertically downwards through its centre of mass, no longer passes through the line of action of the contact force (the force exerted by the surface on which the object is resting), acting vertically upwards through the object's new base. If the lines of action of these two opposite but equal forces do not coincide they will form a couple and create a moment (see moment of a force) that will cause the object either to return to its original rest position or to topple over into another position.

An object in stable equilibrium returns to its rest position after being displaced slightly. This form of equilibrium is found in objects that are difficult to topple over; these usually possess a relatively wide base and a low centre of mass – for example, a cone resting on its flat base on a horizontal surface. When such an object is tilted slightly its centre of mass is raised and the line of action of its weight no longer coincides with that of the contact force exerted by its new, smaller base area. The moment created will tend to lower the centre of mass and so the cone will fall back to its original position.

An object in unstable equilibrium does not remain at rest if displaced, but falls into a new position; it does not return to its original rest position. Objects possessing this form of equilibrium are easily toppled and usually have a relatively small base and a high centre of mass – for example, a cone balancing on its point, or apex, on a horizontal surface.

When an object such as this is given the slightest push its centre of mass is lowered and the displacement of the line of action of its weight creates a moment. The moment will tend to lower the centre of mass still further and so the object will fall on to another position.

An object in neutral equilibrium stays at rest if it is moved into a new position – neither moving back to its original position nor on any further. This form of equilibrium is found in objects that are able to roll, such as a cone resting on its curved side placed on a horizontal surface. When such an object is rolled its centre of mass remains in the same position, neither rising nor falling, and the line of action of its weight continues to coincide with the contact force; no moment is created and so its equilibrium is maintained

Stability : depends on so many things meanly:

• the hight of the car( the more the hight the less the stability)




• size of the wheels ( the wider the tires the more stability)




• width of the car (the more the width the more stability)




• aerodynamics (the smoother the side profile the more stability)

• suspension ( the tougher the suspension is the more the stability in curves)

( effect of tough suspension on the stability)

But the problem is the the tougher the suspension the less comfort

Don't worry there is a system combined between stability and comfort

is called (bose active suspension)

Power & torque

Sure you have read a car description and you found that: Max power: 140 hp @ 6000 rpm
Max torque : 150 Ipft @ 3500 rpm
What's that ?
, what does it describe?
and how important is it?
first you to know the meaning of them actully!!!!!!!!!!!!!!!!!

With getting involved in engineering equations that most people hate:

Force : In physics, a force is a push or pull that can cause an object with mass to change its velocity." The Unit is Newton (N)"

Imagine if if you have 1 kg object and you would like to pull it up you will need 10 N force to do that.

but if you would like to push it in the groung you will only need to overcome the friction force betwwen the object and the ground

In case of cars since it hase wheels it will be easier to push a wieght with wheels but has a friction resistance as well it's called (rolling resistance)

In case of car engines you will need to rotate the wheels to get the motion this is called (torque)

If you want to fasten a bolt with your hands it will be so hard

so you will have to use a wrench and the longer the distance between your hand and the bolt the easier the fastening the bolt .

That's why that torque unit is N.m

Torque: is the tendency of a force to rotate an object about an axis,

or pivot.

Just as a force is a push or a pull, a torque can be thought of as a twist. The symbol for torque is τ. the Greek letter tau.

so now lets assume that you have a torque of 10 N.m and your friend has the same torque 10 N.m but you have the ability to reach this torque at 2 seconds and your friend is in 5 seconds and you and him trie to pull a wight of 10 kg

,you will be able to pull the wight faster than him.

That explaines torque : 100 N.m @ 3000 rpm

this car is able to reach this torque at 3000 rpm

If you and your friend want to run beside each other, both of you ( for example)

reach 20 km/hr but you will reach this speed faster than him

so if we have to cars :

1. torque : 100 N.m @ 3000 rpm

2. torque : 100 n.m @ 1500 rpm

car 2 will accelerate faster that car one because it can reach it's max torque in shorter time.

Car Engines

Internal Combustion

The ­principle behind any reciprocating internal combustion engine:

If you put a tiny amount of high-energy fuel (like gasoline) in a small, enclosed space and ignite it, an incredible amount of energy is released in the form of expanding gas. You can use that energy to propel a potato 500 feet. In this case, the energy is translated into potato motion. You can also use it for more interesting purposes. For example, if you can create a cycle that allows you to set off explosions like this hundreds of times per minute, and if you can harness that energy in a useful way, what you have is the core of a car engine!



Almost all cars currently use what is called a four-stroke combustion cycle to convert gasoline into motion. The four-stroke approach is also known as the Otto cycle, in honor of Nikolaus Otto, who invented it in 1867. They are:
-Intake stroke
-Compression stroke
-Combustion stroke
-Exhaust stroke

The piston starts at the top, the intake valve opens, and the piston moves down to let the engine take in a cylinder-full of air and gasoline. This is the intake stroke. Only the tiniest drop of gasoline needs to be mixed into the air for this to work.
Then the piston moves back up to compress this fuel/air mixture. Compression makes the explosion more powerful.
When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the gasoline. The gasoline charge in the cylinder explodes, driving the piston down.
Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out the tailpipe.
Now the engine is ready for the next cycle, so it intakes another charge of air and gas.

Notice that the motion that comes out of an internal combustion engine is rotational, while the motion produced by a potato cannon is linear (straight line). In an engine the linear motion of the pistons is converted into rotational motion by the crankshaft. The rotational motion is nice because we plan to turn (rotate) the car's wheels with it anyway.
Source : http://www.howstuffworks.com/

Introduction

The most important thing to be able to compare between different models and types of cars is to be awared of what's going on inside these incredible machine .

We will introduce basic about the main components of automobile.

You don't have to be engineer to do this.