Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Reduction Gear shopping experience:

1. Compare - without doubt the biggest advantage that the Reduction Gear offers shoppers today is the ability to compare thousands of Reduction Gear at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Reduction Gear? Wrong! If the Reduction Gear is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Reduction Gear then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Reduction Gear? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Reduction Gear and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Reduction Gear wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Reduction Gear then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Reduction Gear site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Reduction Gear, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Reduction Gear, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.

image:gears_large.jpgThe gear ratio is the relationship between the number of teeth on two gears that are meshed or two sprockets connected with a common roller chain, or the circumferences of two pulleys connected with a drive belt (mechanical).

General description In the picture to the right, the smaller gear has thirteen teeth, while the second, larger gear has twenty-one teeth. The gear ratio is therefore 13/21 or 1/1.62 (also written as 1:1.62).

The first number in the ratio is usually the gear to which power is applied. In an automobile the first number is the gear receiving power from the engine.

This means that for every one revolution of the smaller gear, the larger gear has made 1/1.62, or 0.62, revolutions. In practical terms, the larger gear turns more slowly.

Suppose the largest gear in the picture has 42 teeth, the gear ratio between the second and third gear then is; 21/42 = 1/2 and for every revolution of the smallest gear the largest gear has only turned 0.62/2 = 0.31 revolution, a total reduction of around 1:3.

Since the number of teeth is also Proportionality (mathematics) to the circumference of the gear wheel (the bigger the wheel the more teeth it has) the gear ratio can also be expressed as the relationship between the circumferences of both wheels (where d is the diameter of the smaller wheel and D is the diameter of the larger wheel):

gr = \frac{\pi d}{\pi D} = \frac{d}{D}

Since the diameter is equal to twice the radius; gr = \frac{d}{D} = \frac{2r}{2R} = \frac{r}{R} as well.


Because the gear teeth prevent any slippage at the interface of the two gears, we can assume that their velocities are the same at the contact point, and thus we can arrive at

v_d = v_D \rightarrow \omega_d r = \omega_D R \rightarrow \frac{r}{R} = \frac{\omega_D}{\omega_d} and so gr = \frac{\omega_D}{\omega_d} In other words, the gear ratio is proportional to ratio of the gear diameters and inversely proportional to the ratio of gear speeds.

Counting the teeth derives the exact gear ratio, regardless of any variations in the diameter measurement. In the picture, each time the 13 teeth of the smaller gear make a revolution, 13 teeth of the larger gear will have moved, i.e. made 13/21 of a revolution or 0.62 of a revolution. As long as the gears remain meshed, the accounting of teeth and revolutions will remain perfect. So, for instance, gears can be used to construct a clock in which the minute hand moves exactly twelve times faster than the hour hand, regardless of the overall accuracy of the clock. For example, in one hour the minute hand moves once around the clock (1 C) and the hour hand moves 1/12 of the way around the clock (1/12 C).

Diameter measurements are useful for determining approximate gear ratios for non-gear linkages such as pulleys and belt (mechanical)s. Smooth belts can slip, so even if exact pulley diameters are known quite exactly, the gear ratio may vary in operation, and may even depend on the load.

Belts can have teeth in them also and be coupled to gear-like pulleys. Special gears called sprockets can be coupled together with chains, as on bicycles and some motorcycles. Again, exact accounting of teeth and revolutions can be applied with these machines.

A belt with teeth, called the timing belt, is used in some internal combustion engines to exactly synchronize the movement of the camshaft, so that the poppet valve open and close at the top of each cylinder at exactly the right time to the movement of each cylinder. From the time the car is driven off the lot, to the time the belt needs replacing thousands of kilometers later, it synchronizes the two shafts exactly. A chain, called a timing chain, is used on other automobiles for this purpose. In some automobiles, the camshaft and crankshaft are coupled directly together through meshed gears.

Automobile drivetrains generally have two or more areas where gearing is used: one in the transmission (mechanics), which contains a number of different sets of gearing that can be changed to allow a wide range of vehicle speeds, and another at the differential (mechanics), which contains one additional set of gearing that provides further mechanical advantage at the wheels. These components might be separate and connected by a driveshaft, or they might be combined into one unit called a transaxle.

A 2004 Chevrolet Corvette C5 Z06 with a six-speed manual transmission has the following gear ratios in the transmission:{] gears, in which the output of the transmission is revolving faster than the engine.

The above Corvette has a differential ratio of 3.42:1. This means that for every 3.42 revolutions of the transmission’s output, the wheels make one revolution. The differential ratio multiplies with the transmission ratio, so in 1st gear, the engine makes 10.16 revolutions for every revolution of the wheels.

The car’s tires can almost be thought of as a third type of gearing. The example Corvette Z06 is equipped with 295/35-18 tires, which have a circumference of 82.1 inches. This means that for every complete revolution of the wheel, the car travels 82.1 inches. If the Corvette had larger tires, it would travel farther with each revolution of the wheel, which would be like a higher gear. If the car had smaller tires, it would be like a lower gear.

With the gear ratios of the transmission and differential, and the size of the tires, it becomes possible to calculate the speed of the car for a particular gear at a particular engine revolutions per minute.

For example, it is possible to determine the distance the car will travel for one revolution of the engine by dividing the circumference of the tire by the combined gear ratio of the transmission and differential.

d = \frac{c_t}{gr_t \times gr_d}

It is possible to determine a car’s speed from the engine speed by multiplying the circumference of the tire by the engine speed and dividing by the combined gear ratio.

v_c = \frac{c_t \times v_e}{gr_t \times gr_d}

{| border="1" class="wikitable"!Gear!!Inches per engine revolution!!Speed per 1000 RPM|-|1st gear||8.1 inches||7.7 mph|-|2nd gear||11.6 inches||11.0 mph|-|3rd gear||16.8 inches||15.9 mph|-|4th gear||24.0 inches||22.7 mph|-|5th gear||28.6 inches||27.1 mph|-|6th gear||42.9 inches|| 40.6 mph|}

Wide-ratio vs. Close-ratio Transmission A close-ratio transmission is a transmission in which there is a relatively little difference between the gear ratios of the gears. For example, a transmission with an engine shaft to drive shaft ratio of 4:1 in first gear and 2:1 in second gear would be considered wide-ratio when compared to another transmission with a ratio of 4:1 in first and 3:1 in second. This is because, for the wide-ratio first gear = 4/1 = 4, second gear = 2/1 = 2, so the transmission gear ratio = 4/2 = 2 (or 200%). For the close-ratio first gear = 4/1 = 4, second gear = 3/1 = 3 so the transmission gear ratio = 4/3 = 1.33 (or 133%), because 133% is less than 200%, the transmission with the 133% ratio between gears is considered close-ratio. However, not all transmissions start out with the same ratio in 1st gear or end with the same ratio in 5th gear, which makes comparing wide vs. close transmission more difficult.

Close-ratio transmissions are generally offered in sports cars, in which the engine is tuned for maximum power in a narrow range of operating speeds and the driver can be expected to enjoy shifting often to keep the engine in its power band.

Idler Gears Note that in a sequence of gears chained together, the ratio depends only on the number of teeth on the first and last gear. The intermediate gears, regardless of their size, do not alter the overall gear ratio of the chain. But, of course, the addition of each intermediate gear reverses the direction of rotation of the final gear.

An intermediate gear which doesn't drive a shaft to perform any work is called an idler gear. Sometimes, a single idler gear is used to reverse the direction, in which case it may be referred to as a reverse idler. For instance, the typical automobile manual transmission engages reverse gear by means of inserting a reverse idler between two gears.

Idler gears can also transmit rotation among distant shafts in situations where it would be impractical to simply make the distant gears larger to bring them together. Not only do larger gears occupy more space, but the mass and rotational inertia (moment of inertia) of a gear is quadratic relation in the length of its radius. Instead of idler gears, of course, a toothed belt or chain can be used to transmit torque over distance.

See also

External links

image:gears_large.jpgThe gear ratio is the relationship between the number of teeth on two gears that are meshed or two sprockets connected with a common roller chain, or the circumferences of two pulleys connected with a drive belt (mechanical).

General description In the picture to the right, the smaller gear has thirteen teeth, while the second, larger gear has twenty-one teeth. The gear ratio is therefore 13/21 or 1/1.62 (also written as 1:1.62).

The first number in the ratio is usually the gear to which power is applied. In an automobile the first number is the gear receiving power from the engine.

This means that for every one revolution of the smaller gear, the larger gear has made 1/1.62, or 0.62, revolutions. In practical terms, the larger gear turns more slowly.

Suppose the largest gear in the picture has 42 teeth, the gear ratio between the second and third gear then is; 21/42 = 1/2 and for every revolution of the smallest gear the largest gear has only turned 0.62/2 = 0.31 revolution, a total reduction of around 1:3.

Since the number of teeth is also Proportionality (mathematics) to the circumference of the gear wheel (the bigger the wheel the more teeth it has) the gear ratio can also be expressed as the relationship between the circumferences of both wheels (where d is the diameter of the smaller wheel and D is the diameter of the larger wheel):

gr = \frac{\pi d}{\pi D} = \frac{d}{D}

Since the diameter is equal to twice the radius; gr = \frac{d}{D} = \frac{2r}{2R} = \frac{r}{R} as well.


Because the gear teeth prevent any slippage at the interface of the two gears, we can assume that their velocities are the same at the contact point, and thus we can arrive at

v_d = v_D \rightarrow \omega_d r = \omega_D R \rightarrow \frac{r}{R} = \frac{\omega_D}{\omega_d} and so gr = \frac{\omega_D}{\omega_d} In other words, the gear ratio is proportional to ratio of the gear diameters and inversely proportional to the ratio of gear speeds.

Counting the teeth derives the exact gear ratio, regardless of any variations in the diameter measurement. In the picture, each time the 13 teeth of the smaller gear make a revolution, 13 teeth of the larger gear will have moved, i.e. made 13/21 of a revolution or 0.62 of a revolution. As long as the gears remain meshed, the accounting of teeth and revolutions will remain perfect. So, for instance, gears can be used to construct a clock in which the minute hand moves exactly twelve times faster than the hour hand, regardless of the overall accuracy of the clock. For example, in one hour the minute hand moves once around the clock (1 C) and the hour hand moves 1/12 of the way around the clock (1/12 C).

Diameter measurements are useful for determining approximate gear ratios for non-gear linkages such as pulleys and belt (mechanical)s. Smooth belts can slip, so even if exact pulley diameters are known quite exactly, the gear ratio may vary in operation, and may even depend on the load.

Belts can have teeth in them also and be coupled to gear-like pulleys. Special gears called sprockets can be coupled together with chains, as on bicycles and some motorcycles. Again, exact accounting of teeth and revolutions can be applied with these machines.

A belt with teeth, called the timing belt, is used in some internal combustion engines to exactly synchronize the movement of the camshaft, so that the poppet valve open and close at the top of each cylinder at exactly the right time to the movement of each cylinder. From the time the car is driven off the lot, to the time the belt needs replacing thousands of kilometers later, it synchronizes the two shafts exactly. A chain, called a timing chain, is used on other automobiles for this purpose. In some automobiles, the camshaft and crankshaft are coupled directly together through meshed gears.

Automobile drivetrains generally have two or more areas where gearing is used: one in the transmission (mechanics), which contains a number of different sets of gearing that can be changed to allow a wide range of vehicle speeds, and another at the differential (mechanics), which contains one additional set of gearing that provides further mechanical advantage at the wheels. These components might be separate and connected by a driveshaft, or they might be combined into one unit called a transaxle.

A 2004 Chevrolet Corvette C5 Z06 with a six-speed manual transmission has the following gear ratios in the transmission:{] gears, in which the output of the transmission is revolving faster than the engine.

The above Corvette has a differential ratio of 3.42:1. This means that for every 3.42 revolutions of the transmission’s output, the wheels make one revolution. The differential ratio multiplies with the transmission ratio, so in 1st gear, the engine makes 10.16 revolutions for every revolution of the wheels.

The car’s tires can almost be thought of as a third type of gearing. The example Corvette Z06 is equipped with 295/35-18 tires, which have a circumference of 82.1 inches. This means that for every complete revolution of the wheel, the car travels 82.1 inches. If the Corvette had larger tires, it would travel farther with each revolution of the wheel, which would be like a higher gear. If the car had smaller tires, it would be like a lower gear.

With the gear ratios of the transmission and differential, and the size of the tires, it becomes possible to calculate the speed of the car for a particular gear at a particular engine revolutions per minute.

For example, it is possible to determine the distance the car will travel for one revolution of the engine by dividing the circumference of the tire by the combined gear ratio of the transmission and differential.

d = \frac{c_t}{gr_t \times gr_d}

It is possible to determine a car’s speed from the engine speed by multiplying the circumference of the tire by the engine speed and dividing by the combined gear ratio.

v_c = \frac{c_t \times v_e}{gr_t \times gr_d}

{| border="1" class="wikitable"!Gear!!Inches per engine revolution!!Speed per 1000 RPM|-|1st gear||8.1 inches||7.7 mph|-|2nd gear||11.6 inches||11.0 mph|-|3rd gear||16.8 inches||15.9 mph|-|4th gear||24.0 inches||22.7 mph|-|5th gear||28.6 inches||27.1 mph|-|6th gear||42.9 inches|| 40.6 mph|}

Wide-ratio vs. Close-ratio Transmission A close-ratio transmission is a transmission in which there is a relatively little difference between the gear ratios of the gears. For example, a transmission with an engine shaft to drive shaft ratio of 4:1 in first gear and 2:1 in second gear would be considered wide-ratio when compared to another transmission with a ratio of 4:1 in first and 3:1 in second. This is because, for the wide-ratio first gear = 4/1 = 4, second gear = 2/1 = 2, so the transmission gear ratio = 4/2 = 2 (or 200%). For the close-ratio first gear = 4/1 = 4, second gear = 3/1 = 3 so the transmission gear ratio = 4/3 = 1.33 (or 133%), because 133% is less than 200%, the transmission with the 133% ratio between gears is considered close-ratio. However, not all transmissions start out with the same ratio in 1st gear or end with the same ratio in 5th gear, which makes comparing wide vs. close transmission more difficult.

Close-ratio transmissions are generally offered in sports cars, in which the engine is tuned for maximum power in a narrow range of operating speeds and the driver can be expected to enjoy shifting often to keep the engine in its power band.

Idler Gears Note that in a sequence of gears chained together, the ratio depends only on the number of teeth on the first and last gear. The intermediate gears, regardless of their size, do not alter the overall gear ratio of the chain. But, of course, the addition of each intermediate gear reverses the direction of rotation of the final gear.

An intermediate gear which doesn't drive a shaft to perform any work is called an idler gear. Sometimes, a single idler gear is used to reverse the direction, in which case it may be referred to as a reverse idler. For instance, the typical automobile manual transmission engages reverse gear by means of inserting a reverse idler between two gears.

Idler gears can also transmit rotation among distant shafts in situations where it would be impractical to simply make the distant gears larger to bring them together. Not only do larger gears occupy more space, but the mass and rotational inertia (moment of inertia) of a gear is quadratic relation in the length of its radius. Instead of idler gears, of course, a toothed belt or chain can be used to transmit torque over distance.

See also

External links



 

Reduction Gear



 
Copyright © 2008 Hintcenter.com - All rights reserved.
Home | Terms of Use | Privacy Policy
All Trademarks belong to their repective owners. Many aspects of this page are used under
commercial commons license from Yahoo!