Continuously Variable Transmission, also known as CVT, is a kind of automatic transmission that produces more useable power, improves fuel economy, and gives a smoother ride than the usual automatic transmission.
CVTs and automatics both have the same controls: No clutch pedal and P-R-N-D-L style shift pattern. The difference is that an automatic has a set number of gear ratios, or speeds, usually 4, 5 or 6. With a CVT, the transmission is constantly changing with the engine speed using a pulley system. You will never feel or hear a CVT shift when driving. CVT simply raises and lowers with the engine’s speed as needed, calling up higher engine speeds (or RPMs) for better acceleration and lower RPMs for better fuel economy while cruising.
When people first drive a vehicle with a CVT, they feel unease because of the way the CVT sounds. When you step on the accelerator, the engine races as it would with a slipping clutch in a manual or a failing automatic transmission. This is typical for a CVT, it’s adjusting the engine speed to offer the best possible power the acceleration.
How it Works
Automatic and manual transmissions both use a gear set that uses a number of ratio, or speeds. Both transmissions have: low gears for starting out, middle gears for accelerating and passing, and high gears for fuel-efficient cruising that can be shifted by the transmission itself or the driver.
There are many different styles of CVTs. Most CVTs operate on a pair of variable-diameter, that are shaped like opposing cone, with a metal belt or chain running between them. One pulley is connected to the engine (input shaft), the other to the drive wheels (output shaft). The halves of each pulley are moveable; as the pulley halves come closer together the belt is forced to ride higher on the pulley, effectively making the pulley's diameter larger. Changing the diameter of the pulleys varies the transmission's ratio (the number of times the output shaft revolves for revolution of the engine), in the same way that a 10-speed bike routes the chain over larger or smaller gears to change the ratio. Making the input pulley smaller and the output pulley larger gives a low ratio (a large number of engine revolutions producing a small number of output revolutions) for better low-speed acceleration. As the car accelerates, the pulleys vary their diameter to lower the engine speed as car speed rises. This is the same thing a conventional automatic or manual transmission does, but while a conventional transmission changes the ratio in stages by shifting gears, the CVT continuously varies the ratio; therefore it’s named "continuously variable transmission".
Wednesday, July 30, 2008
Thursday, July 17, 2008
Air Conditioning
The summer heat is just around the corner, and before you turn on the air conditioning on this summer, there’s a couple of things to check out to ensure your A/C is working properly.
Check the drive belt under the hood for wear, cracks and/or even stretches. The drive belt makes the A/C turn, and that keeps the cooling refrigerant circulating like it should. If the drive belt is bad, the belt could slip or break causing the compressor to stop.
The drive belt and compressor are sometimes difficult to locate, particularly in newer vehicles with covers and components that hide them. A mechanic technician can help you locate the belt and compressor next time you take your vehicle to the shop.
The A/C condenser is positioned in front of the vehicle’s radiator, which looks like a mini radiator. Refrigerant goes though the condenser and air flow across its cooling fins, removing heat from the circulating refrigerant.
If the fan fins ever become damaged or plugged up with debris, airflow is limited, causing heat to remain in the air vents. This airflow limitation can cause a vehicle to over-heat. Check the fan fins occasionally to make sure they are clean and in good condition.
Signs of air conditioning problems:
• If your carpet is wet on hot, humid day that is good indication that your A/C drain might be clogged. When the A/C drain is working properly you will see a good amount of water dripping on the ground under the vehicle when it’s in park.
• Any vibration or unusual noise when you turn the fan on could imply debris in the fan. (Mice like to make a nest in the fan).
• A reduced amount of air coming out of the vents probably means that the A/C’s evaporator is freezing up. This particularly happens after driving for awhile.
• Mold or mildew can grow in the evaporator of your A/C. To check if you have mold or mildew growing, turn on your fan, and if you smell a musty or mildew odor, you should check it out.
You can reduce mold and mildew by turning the A/C recirculation switch off when you park your vehicle. If your vehicle doesn’t have a recirculation switch, turn the A/C switch away from the “Max Air” position every time you shut your engine off. Some vehicles will still develop a musty odor, but many service departments offer an evaporator cleaning produce to get rid of the smell.
Most people wonder if running the A/C down the road is fuel efficient. Yes, air conditioner design these days are pretty efficient.
If you discover a problem with your vehicle’s A/C, take the vehicle to a trusted mechanic technician.
Check the drive belt under the hood for wear, cracks and/or even stretches. The drive belt makes the A/C turn, and that keeps the cooling refrigerant circulating like it should. If the drive belt is bad, the belt could slip or break causing the compressor to stop.
The drive belt and compressor are sometimes difficult to locate, particularly in newer vehicles with covers and components that hide them. A mechanic technician can help you locate the belt and compressor next time you take your vehicle to the shop.
The A/C condenser is positioned in front of the vehicle’s radiator, which looks like a mini radiator. Refrigerant goes though the condenser and air flow across its cooling fins, removing heat from the circulating refrigerant.
If the fan fins ever become damaged or plugged up with debris, airflow is limited, causing heat to remain in the air vents. This airflow limitation can cause a vehicle to over-heat. Check the fan fins occasionally to make sure they are clean and in good condition.
Signs of air conditioning problems:
• If your carpet is wet on hot, humid day that is good indication that your A/C drain might be clogged. When the A/C drain is working properly you will see a good amount of water dripping on the ground under the vehicle when it’s in park.
• Any vibration or unusual noise when you turn the fan on could imply debris in the fan. (Mice like to make a nest in the fan).
• A reduced amount of air coming out of the vents probably means that the A/C’s evaporator is freezing up. This particularly happens after driving for awhile.
• Mold or mildew can grow in the evaporator of your A/C. To check if you have mold or mildew growing, turn on your fan, and if you smell a musty or mildew odor, you should check it out.
You can reduce mold and mildew by turning the A/C recirculation switch off when you park your vehicle. If your vehicle doesn’t have a recirculation switch, turn the A/C switch away from the “Max Air” position every time you shut your engine off. Some vehicles will still develop a musty odor, but many service departments offer an evaporator cleaning produce to get rid of the smell.
Most people wonder if running the A/C down the road is fuel efficient. Yes, air conditioner design these days are pretty efficient.
If you discover a problem with your vehicle’s A/C, take the vehicle to a trusted mechanic technician.
Wednesday, July 02, 2008
Tire Pressure and Gas Mileage
Did you know that keeping your tires at the recommended pressure could improve your fuel economy?
Let’s say the correct tire pressure on your tires is suppose to be 35 psi, according to the tire sticker in the inside of the door. If 35 psi is in your tire that means that six square inches of you tire is touching the ground, the way the tire was designed. Now let say some air was let out of the tire and there’s now 30 psi in the tire, eight square inches are now touching the road. Since your tire is like a balloon, the more air you have on the inside, the rounder and more firm your tire becomes. Having eight square inches touch the ground would consume more gas than having six square inches on the ground because it’s harder to turn a tire that is flatter, which makes your engine work harder.
Filling you tires with the correct tire pressure makes your engine run easier and can improve you fuel by three to four miles per gallon. That’s at least 36 more miles to the average tank, and 1,872 more miles in one year. You can check to see what is the correct tire pressure for your tire by checking the tire sticker on the inside of the driver’s door, owner’s manual or on the tire itself.
Let’s say the correct tire pressure on your tires is suppose to be 35 psi, according to the tire sticker in the inside of the door. If 35 psi is in your tire that means that six square inches of you tire is touching the ground, the way the tire was designed. Now let say some air was let out of the tire and there’s now 30 psi in the tire, eight square inches are now touching the road. Since your tire is like a balloon, the more air you have on the inside, the rounder and more firm your tire becomes. Having eight square inches touch the ground would consume more gas than having six square inches on the ground because it’s harder to turn a tire that is flatter, which makes your engine work harder.
Filling you tires with the correct tire pressure makes your engine run easier and can improve you fuel by three to four miles per gallon. That’s at least 36 more miles to the average tank, and 1,872 more miles in one year. You can check to see what is the correct tire pressure for your tire by checking the tire sticker on the inside of the driver’s door, owner’s manual or on the tire itself.
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