Gears on a piece of farm equipment, gear ratio 1:1.62

The 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. Download high resolution version (500x680, 39 KB)Description: Photograph of spur gears on a piece of farm equipment. ... Download high resolution version (500x680, 39 KB)Description: Photograph of spur gears on a piece of farm equipment. ... Spur gears found on a piece of farm equipment A gear is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device -- possibly another gear wheel -- so that force can be transmitted between the two devices in a... This article does not cite its references or sources. ... Roller chain and sprocket Roller chain or bush roller chain is the type of chain most commonly used for transmission of mechanical power on bicycles, motorcycles, and in industrial and agricultural machinery. ... The circumference is the distance around a closed curve. ... For the band, see Pulley (band). ... v-belt flat belt Belts are used to mechanically link two or more rotating items. ...

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. A ratio is a quantity that denotes the proportional amount or magnitude of one quantity relative to another. ...

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 proportional 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): In mathematics, two quantities are called proportional if they vary in such a way that one of the quantities is a constant multiple of the other, or equivalently if they have a constant ratio. ... The circumference is the distance around a closed curve. ... DIAMETER is a computer networking protocol for AAA (Authentication, Authorization and Accounting). ...

Since the diameter is equal to twice the radius; Remote Authentication Dial In User Service (RADIUS) is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ...

as well.

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.

In a clock, when, in an hour, the minute handle moves a distance 1C, the hour handle moves a distance of 1/12 C.

Diameter measurements are useful for determining approximate gear ratios for non-gear linkages such as pulleys and belts. 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. For the band, see Pulley (band). ... v-belt flat belt Belts are used to mechanically link two or more rotating items. ...

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. For other uses, see Bicycle (disambiguation). ... For other uses, see Motorcycle (disambiguation). ...

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 valves 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. Timing belt A timing belt, timing chain or cam belt is a part of an internal combustion engine that controls the timing of the engines valves. ... For the fictional characters of the same name, see Camshaft (Transformers). ... A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ... Timing refers to how events are spaced in time. ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ...

Automobile drivetrains generally have two or more areas where gearing is used: one in the transmission, 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, 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. Drivetrain is the twelfth studio album by southern rock band . ... “Gearbox” redirects here. ... In an automobile and other four-wheeled vehicles, a differential is a device, usually consisting of gears, for allowing each of the driving wheels to rotate at different speeds, while supplying equal torque to each of them. ... This article is about the mechanical device. ... A transaxle, in the automotive field, is a component that combines the functionality of the transmission, the differential and the drive axle into one integrated assembly. ...

A 2004 Chevrolet Corvette C5 Z06 with a six-speed manual transmission has the following gear ratios in the transmission: A 2004 Corvette Z06. ...

In 1st gear, the engine makes 2.97 revolutions for every revolution of the transmission’s output. In 4th gear, the gear ratio of 1:1 means that the engine and the transmission’s output are moving at the same speed. 5th and 6th gears are known as overdrive gears, in which the output of the transmission is revolving faster than the engine. An overdrive is sometimes a separate unit that fits into the back of a gearbox, as with this Fairey unit. ...

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. For other uses, see Wheel (disambiguation). ...

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. This article is about pneumatic tires. ... An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. ...

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 RPM. For other uses, see Revolutions per minute (disambiguation). ...

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.

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.

Miles per hour is a unit of speed, expressing the number of international miles covered per hour. ...

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. 1963 Jaguar E-Type, a classic sports car 1963 Chevrolet Corvette was based upon European sports cars A sports car is an automobile designed for performance driving. ... The power band of an engine refers to the range of operating speeds under which the engine is able to operate efficiently. ...

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 reverse idler between two gears. A manual transmission (also known as a stick shift, straight drive, or standard transmission) is a type of transmission used in automotive applications. ...

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 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. Moment of inertia, also called mass moment of inertia and, sometimes, the angular mass, (SI units kg m², Former British units slug ft2), is the rotational analog of mass. ... Torque applied via an adjustable end wrench Relationship between force, torque, and momentum vectors in a rotating system In physics, torque (or often called a moment) can informally be thought of as rotational force or angular force which causes a change in rotational motion. ...

See also

• Automotive engineering
• Bicycle gearing
• Drag equation
• Mechanical advantage

Automotive engineering is a branch of Vehicle engineering, incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the design, manufacture and operation of automobiles, buses and trucks and their respective engineering subsystems. ... This article does not cite any references or sources. ... In physics, the drag equation gives the drag experienced by an object moving through a fluid. ... In physics and engineering, mechanical advantage (MA) is the factor by which a mechanism multiplies the force put into it. ...

External links

• Gear ratio at How Stuff Works
• "GearCalc" - a program that calculates theoretical maximum speeds in each gear, and speed per 1000 RPM