Have you ever been to or called a parts store to order part(s) for your car or truck, and they asked you about the engine and if its a single or dual overhead cam?
This a common question that parts stores ask a lot and most people don’t know right off. To avoid calling back or going back to the parts store, you can open the hood and sometimes on the engine it has SOHC or DOHC? SOHC means Single Overhead Cam and DOHC means Double Overhead Cam. I will explain the difference between the two in a later blog.
If there’s no SOHC or DOHC on the engine, the Pronto.net's VIN decoder can tell you that information. All you need is the vehicle’s VIN handy, go toPronto.net's VIN decoder, type in the VIN and hit “Submit.” It will provide you with some general information about the vehicle, like the manufacturer, assembly plant, year, make, model, body style, GVWR, (Gross Vehicle Weight Rating.) The site also tells you about the vehicle’s engine (is it DOHC or SOHC), brake system, etc. The
Pronto.net web site is FREE!!!
This information can be printed out so the next time you go to or call the parts store, it will handy.
Monday, January 19, 2009
Thursday, January 08, 2009
Roadside Emergency Kit
Do you have a roadside emergency kit? It’s good to have one for your vehicle in case you have a flat tire, get stuck, your vehicle stalls, or etc… A Roadside Emergency Kit can be bought at department stores like Wal-Mart or Menards or you can order one from the internet. A good kit can be bought for $20-$30.
A homemade Roadside Emergency can easily be made. You might have some item already in your home, otherwise you can purchase them at a store. A good Roadside Emergency Kit include:
• Tow Rope
• Jumper Cables
• Tire Puncture Repair
• Funnel or Cone
• Flashlight
• Batteries
• Gloves
• Emergency Blanket
• Rain Poncho
• Help Flags
• Plastic Zip Ties
• Plastic Water Bag
• First Aid Kit
Some other things you may want to include:
• Water or something to Drink
• Food or Snacks
• Warm, heavy blanket
• Hats and Mitten
• Tools, a socket set
Even through you have an AAA, Cross County, On-Star or etc… membership, you could be waiting a half of hour to one hour before they can arrive to rescue you. In a situation where it’s near or below zero and you have to wait a while, you should consider having these items in your vehicle just in case:
• Warm Blanket
• Water or something to drink
• Food or Snacks
• Hats and Mittens
• First Aid Kit
Roadside Emergency Kits are a valuable item to have in you vehicle, they can help you get back on the road and keep you safe. I hope that nobody is out in the cold for a long time, but just in case you are put a warm heavy blanket in the vehicle before winter hits.
A homemade Roadside Emergency can easily be made. You might have some item already in your home, otherwise you can purchase them at a store. A good Roadside Emergency Kit include:
• Tow Rope
• Jumper Cables
• Tire Puncture Repair
• Funnel or Cone
• Flashlight
• Batteries
• Gloves
• Emergency Blanket
• Rain Poncho
• Help Flags
• Plastic Zip Ties
• Plastic Water Bag
• First Aid Kit
Some other things you may want to include:
• Water or something to Drink
• Food or Snacks
• Warm, heavy blanket
• Hats and Mitten
• Tools, a socket set
Even through you have an AAA, Cross County, On-Star or etc… membership, you could be waiting a half of hour to one hour before they can arrive to rescue you. In a situation where it’s near or below zero and you have to wait a while, you should consider having these items in your vehicle just in case:
• Warm Blanket
• Water or something to drink
• Food or Snacks
• Hats and Mittens
• First Aid Kit
Roadside Emergency Kits are a valuable item to have in you vehicle, they can help you get back on the road and keep you safe. I hope that nobody is out in the cold for a long time, but just in case you are put a warm heavy blanket in the vehicle before winter hits.
Friday, December 19, 2008
Zero And Below Temperatures
Is your car starting hard or not at all in these near zero or below mornings? Does your diesel gel up? We’ve been seeing temperatures near zero and below the past couple of weeks. Here at Overweg Repair, LLC, we’ve been busy with: Jump-starting vehicles because their battery is weak or dead. Pulling diesel trucks in the shop so they can warm-up because they’ve gelled-up. Here are some tips to keep you cars and trucks on the road instead of in the shop:
The cold weather can be brutal on your battery, it’s important to have a good battery for the winter. If you have had your battery for a while, there are some things you can check. The first and easiest thing is to check the posts, if there’s any white corrosion. The posts can be cleaned with a wire brush. When you put the cables back on, make sure they are on the right posts nice and tight. A battery should be tested if you start having problems with it. A mechanic can help you check and test your battery.
When it’s below freezing, leave your vehicle warm-up three or four minutes before you start driving off. That’s not only good for your battery, but its good for all the components on your car or truck. If the temperature drops below ten degrees, it’s good to leave you vehicle idle in neutral when you are warming your car or truck up. This warms-up the transmission fluid. If you have a remote start or start your vehicle, and then decide to not to go, you should leave your vehicle running awhile to recharge your battery, so the next time the vehicle is started you won’t have a weak or dead battery.
Anti-freeze is another thing to check on when it’s below zero, it could freeze. Anti-freeze should be between 30-40 degrees below zero when it’s the radiator. You can buy an anti-freeze tester at a hardware store. A mechanic can assist you checking your anti-freeze.
Diesel engines should be plugged-in over night to help them start in the morning, like gas engines. A diesel engine that will start in the morning doesn’t necessarily mean that it won’t gel-up a mile down the road, unless it had number one diesel the tank. Number one diesel must be used in all diesel engines during the winter months to prevent them from gelling-up. Number one diesel won’t gel-up until forty degrees below zero, whereas number two will gel-up at twenty above zero. Even though number two diesel is about 10-15 cents cheaper than number one, running number one this winter would save you time out of the shop and money on fuel filters.
When a diesel truck is gelled-up, there are only a couple of things you can do to make it start again. Replace the fuel filters and pour some power service diesel 911 into you tanks. If you are able to get your truck pulled into a heated building or shop, and let it thaw out for a hour or two that’s a plus.
By keeping your battery clean and using number one diesel, you’ll spend more time on the road and less in the shop.
The cold weather can be brutal on your battery, it’s important to have a good battery for the winter. If you have had your battery for a while, there are some things you can check. The first and easiest thing is to check the posts, if there’s any white corrosion. The posts can be cleaned with a wire brush. When you put the cables back on, make sure they are on the right posts nice and tight. A battery should be tested if you start having problems with it. A mechanic can help you check and test your battery.
When it’s below freezing, leave your vehicle warm-up three or four minutes before you start driving off. That’s not only good for your battery, but its good for all the components on your car or truck. If the temperature drops below ten degrees, it’s good to leave you vehicle idle in neutral when you are warming your car or truck up. This warms-up the transmission fluid. If you have a remote start or start your vehicle, and then decide to not to go, you should leave your vehicle running awhile to recharge your battery, so the next time the vehicle is started you won’t have a weak or dead battery.
Anti-freeze is another thing to check on when it’s below zero, it could freeze. Anti-freeze should be between 30-40 degrees below zero when it’s the radiator. You can buy an anti-freeze tester at a hardware store. A mechanic can assist you checking your anti-freeze.
Diesel engines should be plugged-in over night to help them start in the morning, like gas engines. A diesel engine that will start in the morning doesn’t necessarily mean that it won’t gel-up a mile down the road, unless it had number one diesel the tank. Number one diesel must be used in all diesel engines during the winter months to prevent them from gelling-up. Number one diesel won’t gel-up until forty degrees below zero, whereas number two will gel-up at twenty above zero. Even though number two diesel is about 10-15 cents cheaper than number one, running number one this winter would save you time out of the shop and money on fuel filters.
When a diesel truck is gelled-up, there are only a couple of things you can do to make it start again. Replace the fuel filters and pour some power service diesel 911 into you tanks. If you are able to get your truck pulled into a heated building or shop, and let it thaw out for a hour or two that’s a plus.
By keeping your battery clean and using number one diesel, you’ll spend more time on the road and less in the shop.
Thursday, November 13, 2008
Tires (Continued)
Last article talked about different types of tires and the letters associated with each type. This article focuses on the numbers on the sidewalls of tires. Each set of numbers means something specific about a tire.
Take P225/50R16 91S for example, the “P” means passenger tire, as mentioned in the last article. The “225” describes the section width of a tire. Section width basically tells how wide the tire is, and measure in millimeters, not inches. Section width is determined by the distance between the widest part of the outside sidewall across to the widest part of the inner sidewall when mounted on the correct wheel width. 225mm can be converted into inches by dividing 225 by 25.4 ( the number of millimeter in one inch.) The result is 8.86 inches wide.
The “50” in P225/50R16 91S describes the tire’s sidewall height, from edge of the rim the top of the tread. The sidewall’s height is referred as the tire’s aspect ratio, profile or series. The “50” is a percentage of the section width, which means the sidewall height or aspect ratio is 50% of 225mm. Like section width, the section profile is measured by millimeters. To convert section profile to inches, you divide 225 by 25.4, which will tell the section width in inches. Then take 50% of the section width in inches to get the end result of 4.43” tall. Now take P255/70R16 for example, you would first convert the section width to inches, which is 8.86”. Then take 70% of the result to end up with 6.20” for the sidewall profile.
The “R” in P225/50R16 tells you about the tire’s internal construction. The tire’s internal construction is designed three ways. The “R” stands for radial construction meaning the tire’s body plies run parallel to each other around the tire. Body plies are referred to as a rubber-coated layer of fabric containing cords that run parallel to each other, extends from bead to bead and goes between the inner liner and belts or tread. The number of plies determines how strong the tire is. Radial tires are the most popular tire being sold today. They are used for cars, SUV’s and light pickup trucks.
If there’s a “D” in the tire size, like 225/50D16, it means that the internal body plies are crisscross diagonally and has a “bias ply” construction. These types tires are stronger and able to carry a heavier load. Bias ply construction tires can be used for light trucks and spare tires.
In 225/50B16, the “B” means that the internal body plies are not only crisscross diagonally, but that have reinforced with belt under the tread area. This type of construction is called “Belted.” Belted construction tires are practically extinct.
Bias ply and belted construction are not designed for speed where as the radial tires are. For more information on the internal construction of tires, go to http://www.4crawler.com/Diesel/Tires.shtml.
The “16” in P225/50R16 refers to the diameter of the wheel (or the rim) and tire. Tire and wheel diameters are expressed in inches. There are different wheel and tire sizes, anywhere from 8” to 28” that fit on all types of vehicles, trailers and trucks.
Some wheels and tires will have diameters in halves, like R16.5, R17.5 R19.5. These tires are used on some heavy-duty trailers and light trucks and cargo vans.
When a tire has a 91S after the tire size, like P225/50R16 91S. 91S stands for the tire’s service description. Service description refers to the tire's Load Index and Speed Rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991. For more information on Service Descriptions, go to http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=35.
The tire’s DOT is a 12-digit code that is on every single tire given by the Department of Transportation. It’s way to locate a tire like a tracking number. DOT provides information like: 1st and 2nd characters are the manufacturer and plant code. 3rd and 4th characters are the tire size. Characters 5th-8th identifies the brand as well as other characteristics. 9th-12th characters: The last four numbers represent the date the tire was made. The first two numbers indicate the week and the last two numbers is the year. For example 0507, indicates the tire was made in the 5th week of 2007)
Take P225/50R16 91S for example, the “P” means passenger tire, as mentioned in the last article. The “225” describes the section width of a tire. Section width basically tells how wide the tire is, and measure in millimeters, not inches. Section width is determined by the distance between the widest part of the outside sidewall across to the widest part of the inner sidewall when mounted on the correct wheel width. 225mm can be converted into inches by dividing 225 by 25.4 ( the number of millimeter in one inch.) The result is 8.86 inches wide.
The “50” in P225/50R16 91S describes the tire’s sidewall height, from edge of the rim the top of the tread. The sidewall’s height is referred as the tire’s aspect ratio, profile or series. The “50” is a percentage of the section width, which means the sidewall height or aspect ratio is 50% of 225mm. Like section width, the section profile is measured by millimeters. To convert section profile to inches, you divide 225 by 25.4, which will tell the section width in inches. Then take 50% of the section width in inches to get the end result of 4.43” tall. Now take P255/70R16 for example, you would first convert the section width to inches, which is 8.86”. Then take 70% of the result to end up with 6.20” for the sidewall profile.
The “R” in P225/50R16 tells you about the tire’s internal construction. The tire’s internal construction is designed three ways. The “R” stands for radial construction meaning the tire’s body plies run parallel to each other around the tire. Body plies are referred to as a rubber-coated layer of fabric containing cords that run parallel to each other, extends from bead to bead and goes between the inner liner and belts or tread. The number of plies determines how strong the tire is. Radial tires are the most popular tire being sold today. They are used for cars, SUV’s and light pickup trucks.
If there’s a “D” in the tire size, like 225/50D16, it means that the internal body plies are crisscross diagonally and has a “bias ply” construction. These types tires are stronger and able to carry a heavier load. Bias ply construction tires can be used for light trucks and spare tires.
In 225/50B16, the “B” means that the internal body plies are not only crisscross diagonally, but that have reinforced with belt under the tread area. This type of construction is called “Belted.” Belted construction tires are practically extinct.
Bias ply and belted construction are not designed for speed where as the radial tires are. For more information on the internal construction of tires, go to http://www.4crawler.com/Diesel/Tires.shtml.
The “16” in P225/50R16 refers to the diameter of the wheel (or the rim) and tire. Tire and wheel diameters are expressed in inches. There are different wheel and tire sizes, anywhere from 8” to 28” that fit on all types of vehicles, trailers and trucks.
Some wheels and tires will have diameters in halves, like R16.5, R17.5 R19.5. These tires are used on some heavy-duty trailers and light trucks and cargo vans.
When a tire has a 91S after the tire size, like P225/50R16 91S. 91S stands for the tire’s service description. Service description refers to the tire's Load Index and Speed Rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991. For more information on Service Descriptions, go to http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=35.
The tire’s DOT is a 12-digit code that is on every single tire given by the Department of Transportation. It’s way to locate a tire like a tracking number. DOT provides information like: 1st and 2nd characters are the manufacturer and plant code. 3rd and 4th characters are the tire size. Characters 5th-8th identifies the brand as well as other characteristics. 9th-12th characters: The last four numbers represent the date the tire was made. The first two numbers indicate the week and the last two numbers is the year. For example 0507, indicates the tire was made in the 5th week of 2007)
Thursday, October 02, 2008
Tires
When looking at a tire on a car, light truck or trailer, there’s a lot of information on that tire besides the brand and name of the tire. All the letters and number mean something specific about that tire. After reading this blog you should have a better understanding of some of the letters and numbers on a tire.
First we will begin with the size of a tire. The tire size is usually in bigger print than the rest of the letters and numbers. Take tire size P225/50R16 91S for example:
The P means that the tire is a “P-metric” size that was intended for a passenger vehicle. Passenger vehicles are classified as cars, mini vans, sport utility vehicles and light trucks, like ¼ and ½ ton trucks. The P-metric size tires started in the 1970s and are the most commonly used tire today.
If there is no letter in front of the three-digit numeric portion of a tire size, for example 225/50R16 91S, it means that the tire is a “Metric” size, also known as “Euro-Metric”. Euro-Metric sizes originated in Europe. These sizes have the same dimension as P-metric sizes, but P-metric sizes tend to handle more weight.
The “T” in T125/90D16 98M means that the tire is a Temporary Spare, also known as space saver or mini spare. Temporary Spare was designed to be temporarily used only until a flat tire can be repaired or replaced.
The “LT” in LT245/75R16 means that the tire is Light Truck-metric size. LT tires are designed to use on vehicles that are capable of carrying heavy cargo or towing large cargo. Three-quarter or one ton full-size pickups usually have light truck tires on them, as well as some big SUVs and full-size vans. Tires that are marked with the "LT" label are the "little brothers" of 18-wheel tractor-trailer tires and are designed to provide large capacity to accept the additional stresses of carrying heavy cargo.
If a tire size ends in “LT”, 7.50R16LT, that means the tire is a earlier “Numeric”, “Wide Base” or “Floatation”. For carrying or towing heavy cargo loads, these are called Numeric sizes. For 16.5-inch diameter or wider are known as Wide Base sizes. Flotation sizes are used to keep control of a vehicle on loose dirt or sandy surfaces. These tires can be found on three-quarter or one ton full-size pickups, big SUVs and full-vans.
In 195/70R15C, the “C” means Commercial tire. Commercial tires are used on full-size vans and delivery trucks that are capable of hauling heavy loads. In addition to being branded with the "C" in their size, these tires are also branded with their appropriate Service Description and "Load Range" (Load Range B, Load Range C or Load Range D). Load Range is the strength of the tire and ability to hold air pressure. Load Ranges are identified by the alphabet, in ascending order. “F” is the highest rating
The “ST” in ST225/75R15 means the tire is a Special Trailer Service size. This tire is used for boat, car and utility trailers. ST-sized tires should never be used on cars, vans or light trucks.
First we will begin with the size of a tire. The tire size is usually in bigger print than the rest of the letters and numbers. Take tire size P225/50R16 91S for example:
The P means that the tire is a “P-metric” size that was intended for a passenger vehicle. Passenger vehicles are classified as cars, mini vans, sport utility vehicles and light trucks, like ¼ and ½ ton trucks. The P-metric size tires started in the 1970s and are the most commonly used tire today.
If there is no letter in front of the three-digit numeric portion of a tire size, for example 225/50R16 91S, it means that the tire is a “Metric” size, also known as “Euro-Metric”. Euro-Metric sizes originated in Europe. These sizes have the same dimension as P-metric sizes, but P-metric sizes tend to handle more weight.
The “T” in T125/90D16 98M means that the tire is a Temporary Spare, also known as space saver or mini spare. Temporary Spare was designed to be temporarily used only until a flat tire can be repaired or replaced.
The “LT” in LT245/75R16 means that the tire is Light Truck-metric size. LT tires are designed to use on vehicles that are capable of carrying heavy cargo or towing large cargo. Three-quarter or one ton full-size pickups usually have light truck tires on them, as well as some big SUVs and full-size vans. Tires that are marked with the "LT" label are the "little brothers" of 18-wheel tractor-trailer tires and are designed to provide large capacity to accept the additional stresses of carrying heavy cargo.
If a tire size ends in “LT”, 7.50R16LT, that means the tire is a earlier “Numeric”, “Wide Base” or “Floatation”. For carrying or towing heavy cargo loads, these are called Numeric sizes. For 16.5-inch diameter or wider are known as Wide Base sizes. Flotation sizes are used to keep control of a vehicle on loose dirt or sandy surfaces. These tires can be found on three-quarter or one ton full-size pickups, big SUVs and full-vans.
In 195/70R15C, the “C” means Commercial tire. Commercial tires are used on full-size vans and delivery trucks that are capable of hauling heavy loads. In addition to being branded with the "C" in their size, these tires are also branded with their appropriate Service Description and "Load Range" (Load Range B, Load Range C or Load Range D). Load Range is the strength of the tire and ability to hold air pressure. Load Ranges are identified by the alphabet, in ascending order. “F” is the highest rating
The “ST” in ST225/75R15 means the tire is a Special Trailer Service size. This tire is used for boat, car and utility trailers. ST-sized tires should never be used on cars, vans or light trucks.
Tuesday, September 02, 2008
Hybrids: How They Work
Hybrid vehicles have two or more propulsion systems, which means driving or pushing forward. Current hybrids consist of an internal combustion engine, electric motor, and battery.
Depending on the type, design, and the use of the hybrid; hybrid designs can range from operating mostly on the internal combustion engine with some assistance from the electric motor, to operating mainly on the electric motor, using the internal combustion engine only when considerable amount of power is demanded.
There are three basic types of hybrids:
• Mild: the electric motor and battery acts as an assistant to the internal combustion engine.
• Full: the two propulsion systems, the electric motor and internal combustion engine, can work independently or in conjunction with each other.
•Plug-in: the internal combustion engine only is used for as a back-up to the main rechargeable motor and battery system.
How does each type work?
The mild and full hybrid systems never have to be plugged in.
A mild hybrid system needs the internal combustion engine running at all times to drive the vehicle. The engine acts as an assistant to the electric motor. The electric motor cannot drive alone.
Unlike a mild hybrid, a full hybrid can drive only on the electric motor, without the internal combustion engine operating. However, the full hybrid is only able to operate like this under light cruising and low acceleration conditions. As soon as significant power in desired, the engine kicks-in to additional power.
A full hybrid system gets better mileage than mild hybrids, plus much more mileage in the city, since the electric motor is likely to get used the most in the city.
Plug-in hybrids are just like their name, they plug-in in to a 110-volt household current. Unlike other hybrids where the engine kicks in when more speed and power is needed, the plug-in hybrid’s engine only kicks-in when the battery charge is low and then the battery recharges. The plug-in hybrids are able to go 20 to 60 miles on their electric charge. When the vehicle is stopped and the battery needs to be recharge, it can be plugged-in and forgotten about until next time it is used.
Plug-in hybrids are not available in the car market yet.
Depending on the type, design, and the use of the hybrid; hybrid designs can range from operating mostly on the internal combustion engine with some assistance from the electric motor, to operating mainly on the electric motor, using the internal combustion engine only when considerable amount of power is demanded.
There are three basic types of hybrids:
• Mild: the electric motor and battery acts as an assistant to the internal combustion engine.
• Full: the two propulsion systems, the electric motor and internal combustion engine, can work independently or in conjunction with each other.
•Plug-in: the internal combustion engine only is used for as a back-up to the main rechargeable motor and battery system.
How does each type work?
The mild and full hybrid systems never have to be plugged in.
A mild hybrid system needs the internal combustion engine running at all times to drive the vehicle. The engine acts as an assistant to the electric motor. The electric motor cannot drive alone.
Unlike a mild hybrid, a full hybrid can drive only on the electric motor, without the internal combustion engine operating. However, the full hybrid is only able to operate like this under light cruising and low acceleration conditions. As soon as significant power in desired, the engine kicks-in to additional power.
A full hybrid system gets better mileage than mild hybrids, plus much more mileage in the city, since the electric motor is likely to get used the most in the city.
Plug-in hybrids are just like their name, they plug-in in to a 110-volt household current. Unlike other hybrids where the engine kicks in when more speed and power is needed, the plug-in hybrid’s engine only kicks-in when the battery charge is low and then the battery recharges. The plug-in hybrids are able to go 20 to 60 miles on their electric charge. When the vehicle is stopped and the battery needs to be recharge, it can be plugged-in and forgotten about until next time it is used.
Plug-in hybrids are not available in the car market yet.
Wednesday, July 30, 2008
CVT
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".
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".
Subscribe to:
Posts (Atom)
