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Encyclopedia > Manual transmission
Transmission types
Manual

Non-synchronous
Automatic “Gearbox” redirects here. ... A sequential manual transmission (or sequential manual gearbox) is a type of manual transmission used on motorbikes and high-performance cars or auto racing, where gears are selected in order and random access to specific gears is not possible. ... A non-synchronous transmission is a form of transmission based on gears that do not use synchronizing mechanisms. ... The automatic gear selector in a Ford Five Hundred vehicle An automatic transmission is an automobile gearbox that can change gear ratios automatically as the vehicle moves, thus freeing the driver from having to shift gears manually (similar but larger devices are also used for railroad locomotives). ...

Semi-automatic Tiptronic is a type of discrete automatic transmission developed by Porsche and used in its vehicles and those of its licensees. ... Semi-automatic transmission, or also known as clutchless manual transmission, automated manual transmission, e-gear, or paddle shift gearbox is a system which uses electronic sensors, processors and actuators to do gear shifts on the command of the driver. ...

Continuously-variable
Bicycle gearing
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A manual transmission (also known as a stick shift, straight drive, or standard transmission) is a type of transmission used in automotive applications. Manual transmissions often feature a driver-operated clutch and a movable gear selector. Most automobile manual transmissions allow the driver to select any gear at any time, but some, such as those commonly mounted on motorcycles and some types of racing cars, only allow the driver to select the next-highest or next-lowest gear ratio. This second type of transmission is sometimes called a sequential (manual) transmission. A Twin-clutch gearbox or Dual Clutch Transmission (DCT) is a semi-automatic transmission with separate clutches for odd and even gears. ... Saxomat was a type of automatic clutch available as an option on Saab 93, Volkswagen Beetle, Borgward, DKW, BMW, Opel, NSU and Glas. ... The continuously variable transmission (CVT) is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios. ... Variomatic Variomatic is the stepless, fully automatic transmission of the Dutch car manufacturer DAF, using a drive belt and two pulleys. ... Audi developed a new stepless transmission named Multitronic. ... This article does not cite any references or sources. ... Shimano XT rear derailleur on a mountain bike Derailleur gears are a variable ratio transmission system commonly used on bicycles, consisting of a chain, multiple sprockets and a mechanism to move the chain from one sprocket to another. ... Hub gears or internal-gear hubs are a type of gear system used on bicycles. ... “Gearbox” redirects here. ... Car redirects here. ... This article does not cite any references or sources. ... For other uses, see Clutch (disambiguation). ... 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... For other uses, see Motorcycle (disambiguation). ... Gears on a piece of farm equipment, gear ratio 1:1. ...


Manual transmissions are characterized by gear ratios that are selectable by engaging pairs of gears inside the transmission. Conversely, most automatic transmissions feature epicyclic (planetary) gearing controlled by brake bands and/or clutch packs to select gear ratio. Automatic transmissions that allow the driver to manually select the current gear are called semi-automatic transmissions. The automatic gear selector in a Ford Five Hundred vehicle An automatic transmission is an automobile gearbox that can change gear ratios automatically as the vehicle moves, thus freeing the driver from having to shift gears manually (similar but larger devices are also used for railroad locomotives). ... Epicyclic gearing is used here to increase output speed. ... Epicyclic gearing is used here to increase output speed. ... The automatic gear selector in a Ford Five Hundred vehicle An automatic transmission is an automobile gearbox that can change gear ratios automatically as the vehicle moves, thus freeing the driver from having to shift gears manually (similar but larger devices are also used for railroad locomotives). ... Semi-automatic transmission, or also known as clutchless manual transmission, automated manual transmission, e-gear, or paddle shift gearbox is a system which uses electronic sensors, processors and actuators to do gear shifts on the command of the driver. ...


Contemporary automotive manual transmissions are generally available with four to six forward gears and one reverse gear, although manual transmissions have been built with as few as two and as many as eight gears. Semi-trucks have at least 13 gears and as many as 24. Some manuals are referred to by the number of forward gears they offer (e.g., 5-speed) as a way of distinguishing between automatic or other available manual transmissions. Similarly, a 5-speed automatic transmission is referred to as a 5-speed automatic. This article does not cite any references or sources. ...


Other types of transmission in mainstream automotive use are the automatic transmission, semi-automatic transmission, and the continuously variable transmission. The automatic gear selector in a Ford Five Hundred vehicle An automatic transmission is an automobile gearbox that can change gear ratios automatically as the vehicle moves, thus freeing the driver from having to shift gears manually (similar but larger devices are also used for railroad locomotives). ... Semi-automatic transmission, or also known as clutchless manual transmission, automated manual transmission, e-gear, or paddle shift gearbox is a system which uses electronic sensors, processors and actuators to do gear shifts on the command of the driver. ... The continuously variable transmission (CVT) is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios. ...


Manual transmissions come in two basic types: simple Non-synchronous systems, where gears are spinning freely and their relative speeds must be synchronized by the operator to avoid noisy and damaging "clashing" and "grinding" when trying to mesh the rotating teeth; and synchronized systems, which eliminate this necessity while changing gears.

Contents

Unsynchronized transmission

The earliest vehicle transmissions were entirely mechanical unsynchronized [citation needed] gearing systems. They could be shifted, with multiple gear ratios available to the operator, and even had reverse. However, the gears were engaged by sliding mechanisms or simple clutches, which required a lot of careful timing and throttle manipulation when shifting, so that the gears would be spinning at roughly the same speed when engaged; otherwise, the teeth would refuse to mesh. In an engine, the throttle is the mechanism by which the engines power is increased or decreased. ...


When upshifting, the speed of the gear driven by the engine had to drop to match the speed of the next gear; as this happened naturally when the clutch was depressed or disengaged, it was just a matter of skill and experience to hear and feel when the gears managed to mesh. However, when downshifting, the gear driven by the engine had to be speed up to mesh with the output gear, requiring letting the clutch up (engagement) for the engine to speed up the gears. Double declutching, that is, shifting once to neutral to speed up the gears and again to the lower gear, is sometimes needed. In fact, such transmissions are often easier to shift without using the clutch at all. When using this method, the driver has to time the shift with relative precision to avoid grinding the gears. The clutch, in these cases, is only used for starting from a standstill. This procedure is common in racing vehicles and most production motorcycles. For other uses, see Clutch (disambiguation). ... The double declutch (or, more simply, double clutch) is a driving technique that is somewhat harder to describe than to learn how to do. ...


Even though automotive transmissions are now almost universally synchronised, heavy trucks and machinery as well as dedicated racing transmissions are usually non-synchromesh transmissions, known colloquially as "crashboxes", for several reasons. The friction material, such as brass, in synchronizers is more prone to wear and breakage than gears, which are forged steel, and the simplicity of the mechanism improves reliability and reduces cost. In addition, the process of shifting a synchromesh transmission is slower than that of shifting a non-synchromesh transmission. For racing of production-based transmissions, sometimes half the teeth (or "dogs") on the synchros are removed to speed the shifting process, at the expense of greater wear. For other uses, see Truck (disambiguation). ... Auto racing (also known as automobile racing or autosport) is a sport involving racing automobiles. ...


Heavy duty trucks utilize unsynchronized transmissions in the interest of saving weight. Military edition trucks, which do not have to obey weight laws, usually have a synchronized transmission. Highway use heavy-duty trucks in the United States are limited to 80,000 pounds GVWR, and the lighter the curb weight for the truck, the more cargo can be carried, and with a synchronizer adding weight to a truck that could otherwise be used to carry cargo, most drivers are simply taught how to double clutch.


Similarly, most modern motorcycles still utilize unsynchronised transmissions as synchronisers are generally not necessary or desirable. Their low gear inertias and higher strengths mean that 'forcing' the gears to alter speed is not damaging, and the selector method on modern motorcycles (pedal operated) is not conducive to having the long shift time of a synchronised gearbox. Because of this, it is still necessary to synchronise gear speeds by "blipping" the throttle when shifting into a lower gear on a motorcycle. Shift time refers to the amount of time without power between gears usually with reference to motor vehicles but can apply to any gearbox. ...


Synchronized transmission

Top and side view of a typical manual transmission, in this case a Ford "Toploader", used in cars with external floor shifters.
Top and side view of a typical manual transmission, in this case a Ford "Toploader", used in cars with external floor shifters.

Modern gearboxes are constant mesh, i.e. all gears are always in mesh. Only one of these meshed pairs of gears is locked to the shaft on which it is mounted at any one time, while the others are allowed to rotate freely. Thus, it greatly reduces the skill required to shift gears. Image File history File linksMetadata Ford_Design_3-speed_OD_Transmission_w. ... Image File history File linksMetadata Ford_Design_3-speed_OD_Transmission_w. ... Toploader 4 speed for a Ford Mustang A Toploader transmission is a manually actuated three and four speed gearbox introduced in 1964 by Ford Motor Company to replace the BorgWarner T-10. ...


Most modern cars are fitted with a synchronized gear box, although it is entirely possible to construct a constant mesh gearbox without a synchromesh, as found in a motorcycle, for example. In a constant mesh gearbox, the transmission gears are always in mesh and rotating, but the gears are not rigidly connected to the shafts on which they rotate. Instead, the gears can freely rotate or be locked to the shaft on which they are carried. The locking mechanism for any individual gear consists of a collar (or "dog collar") on the shaft which is able to slide sideways so that teeth (or "dogs") on its inner surface bridge two circular rings with teeth on their outer circumference: one attached to the gear, one to the shaft (one collar typically serves for two gears; sliding in one direction selects one transmission speed, in the other direction selects the other). When the rings are bridged by the collar, that particular gear is rotationally locked to the shaft and determines the output speed of the transmission. In a synchromesh gearbox, to correctly match the speed of the gear to that of the shaft as the gear is engaged, the collar initially applies a force to a cone-shaped brass clutch which is attached to the gear, which brings the speeds to match prior to the collar locking into place. The collar is prevented from bridging the locking rings when the speeds are mismatched by synchro rings (also called blocker rings or balk rings, the latter being spelled "baulk" in the UK). The gearshift lever manipulates the collars using a set of linkages, so arranged so that one collar may be permitted to lock only one gear at any one time; when "shifting gears," the locking collar from one gear is disengaged and that of another engaged. In a modern gearbox, the action of all of these components is so smooth and fast it is hardly noticed. Linkage can refer to: Genetic linkage Linkage (mechanical engineering) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...


The first synchronized transmission system was introduced by Cadillac in 1929[citation needed]. The modern cone system was developed by Porsche and introduced in the 1952 Porsche 356; cone synchronizers were called "Porsche-type" for many years after this. In the early 1950s only the second-third shift was synchromesh in most cars, requiring only a single synchro and a simple linkage; drivers' manuals in cars suggested that if the driver needed to shift from second to first, it was best to come to a complete stop then shift into first and start up again. With continuing sophistication of mechanical development, however, fully synchromesh transmissions with three speeds, then four speeds, five speeds, six speeds and so on became universal by the 1960s. Reverse gear, however, is usually not synchromesh, as there is only one reverse gear in the normal automotive transmission and changing gears in reverse is not required. Cadillac is a brand of luxury automobile, part of the General Motors corporation, produced and mostly sold in the USA; outside of North America, they have been less successful. ... Year 1929 (MCMXXIX) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar. ... This article is about the auto company. ... Year 1952 (MCMLII) was a leap year starting on Tuesday (link will display full calendar) of the Gregorian calendar. ... The Porsche 356 was a sports car produced from 1948 through 1965. ... The 1950s decade refers to the years 1950 to 1959 inclusive. ... The 1960s decade refers to the years from 1960 to 1969, inclusive. ...


Internals

Shafts

Like other transmissions, a manual transmission has several shafts with various gears and other components attached to them. Typically, a rear-wheel-drive transmission has three shafts: an input shaft, a countershaft and an output shaft. The countershaft is sometimes called a layshaft.


In a rear-wheel-drive transmission, the input and output shaft lie along the same line, and may in fact be combined into a single shaft within the transmission. This single shaft is called a mainshaft. The input and output ends of this combined shaft rotate independently, at different speeds, which is possible because one piece slides into a hollow bore in the other piece, where it is supported by a bearing. Sometimes the term mainshaft refers to just the input shaft or just the output shaft, rather than the entire assembly.


In some transmissions, it's possible for the input and output components of the mainshaft to be locked together to create a 1:1 gear ratio, causing the power flow to bypass the countershaft. The mainshaft then behaves like a single, solid shaft, a situation referred to as direct drive.


Even in transmissions that do not feature direct drive, it's an advantage for the input and output to lie along the same line, because this reduces the amount of torsion that the transmission case has to bear. Look up torsion in Wiktionary, the free dictionary. ...


Under one possible design, the transmission's input shaft has just one pinion gear, which drives the countershaft. Along the countershaft are mounted gears of various sizes, which rotate when the input shaft rotates. These gears correspond to the forward speeds and reverse. Each of the forward gears on the countershaft is permanently meshed with a corresponding gear on the output shaft. However, these driven gears are not rigidly attached to the output shaft: although the shaft runs through them, they spin independently of it, which is made possible by bearings in their hubs. Reverse is typically implemented differently, see the section on Reverse. A bearing is a component used to reduce friction in a machine. ... A manual transmission (also known as a stick shift, straight drive, or standard transmission) is a type of transmission used in automotive applications. ...


Most front-wheel-drive transmissions for transverse engine mounting are designed differently. For one thing, they have an integral final drive and differential. For another, they usually have only two shafts; input and countershaft, sometimes called input and output. The input shaft runs the whole length of the gearbox, and there is no separate input pinion. At the end of the second (counter/output) shaft is a pinion gear that mates with the ring gear on the differential.


Front-wheel and rear-wheel-drive transmissions operate similarly. When the transmission is in neutral, and the clutch is disengaged, the input shaft, clutch disk and countershaft can continue to rotate under their own inertia. In this state, the engine, the input shaft and clutch, and the output shaft all rotate independently.


Dog clutch

The gear selector does not engage or disengage the actual gear teeth which are permanently meshed. Rather, the action of the gear selector is to lock one of the freely spinning gears to the shaft that runs through its hub. The shaft then spins together with that gear. The output shaft's speed relative to the countershaft is determined by the ratio of the two gears: the one permanently attached to the countershaft, and that gear's mate which is now locked to the output shaft.


Locking the output shaft with a gear is achieved by means of a dog clutch selector. The dog clutch is a sliding selector mechanism which is splined to the output shaft, meaning that its hub has teeth that fit into slots (splines) on the shaft, forcing it to rotate with that shaft. However, the splines allow the selector to move back and forth on the shaft, which happens when it is pushed by a selector fork that is linked to the gear lever. The fork does not rotate, so it is attached to a collar bearing on the selector. The selector is typically symmetric: it slides between two gears and has a synchromesh and teeth on each side in order to lock either gear to the shaft.


Synchromesh

If the teeth, the so-called dog teeth, make contact with the gear, but the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a modern dog clutch in an automobile has a synchronizer mechanism or synchromesh, where before the teeth can engage, a cone clutch is engaged which brings the selector and gear to the same speed. Moreover, until synchronization occurs, the teeth are prevented from making contact, because further motion of the selector is prevented by a blocker (or "baulk") ring. When synchronization occurs, friction on the blocker ring is relieved and it twists slightly, bringing into alignment certain grooves and notches that allow further passage of the selector which brings the teeth together. Of course, the exact design of the synchronizer varies from manufacturer to manufacturer. A cone clutch serves the same purpose as a disk or plate clutch. ...


The synchronizer[1] has to change the momentum of the entire input shaft and clutch disk. Additionally, it can be abused by exposure to the momentum and power of the engine itself, which is what happens when attempts are made to select a gear without fully disengaging the clutch. This causes extra wear on the rings and sleeves, reducing their service life. When an experimenting driver tries to "match the revs" on a synchronized transmission and force it into gear without using the clutch, the synchronizer will make up for any discrepancy in RPM. The success in engaging the gear without clutching can deceive the driver into thinking that the RPM of the layshaft and transmission were actually exactly matched. Nevertheless, approximate "rev-matching" with clutching can decrease the general delta between layshaft and transmission and decrease synchro wear.


Reverse

The previous discussion applies to the forward gears. The implementation of the reverse gear is usually different, implemented in the following way to reduce the cost of the transmission. Reverse is also a pair of gears: one gear on the countershaft and one on the output shaft. However, whereas all the forward gears are always meshed together, there is a gap between the reverse gears. Moreover, they are both attached to their shafts: neither one rotates freely about the shaft. What happens when reverse is selected is that a small gear, called an idler gear or reverse idler, is slid between them. The idler has teeth which mesh with both gears, and thus it couples these gears together and reverses the direction of rotation without changing the gear ratio. Gears on a piece of farm equipment, gear ratio 1:1. ...


Thus, in other words, when reverse gear is selected, in fact it is actual gear teeth that are being meshed, with no aid from a synchronization mechanism. For this reason, the output shaft must not be rotating when reverse is selected: the car must be stopped. In order that reverse can be selected without grinding even if the input shaft is spinning inertially, there may be a mechanism to stop the input shaft from spinning. The driver brings the vehicle to a stop, and selects reverse. As that selection is made, some mechanism in the transmission stops the input shaft. Both gears are stopped and the idler can be inserted between them. There is a clear description of such a mechanism in the Honda Civic 1996-1998 Service Manual, which refers to it as a "noise reduction system": The Honda Civic is a compact car manufactured by Honda. ...

Whenever the clutch pedal is depressed to shift into reverse, the mainshaft continues to rotate because of its inertia. The resulting speed difference between mainshaft and reverse idler gear produces gear noise [grinding]. The reverse gear noise reduction system employs a cam plate which was added to the reverse shift holder. When shifting into reverse, the 5th/reverse shift piece, connected to the shift lever, rotates the cam plate. This causes the 5th synchro set to stop the rotating mainshaft. (13-4)

A reverse gear implemented this way makes a loud whining sound, which is not heard in the forward gears. The teeth on the forward gears of consumer automobiles are helically cut. When helical gears rotate, their teeth slide together, which results in quiet operation. In spite of all forward gears being always meshed, they do not make a sound that can be easily heard above the engine noise. By contrast, reverse gears are spur gears, meaning that they have straight teeth, in order to allow for the sliding engagement of the idler, which would not be possible with helical gears. The teeth of spur gears clatter together when the gears spin, generating a characteristic whine. 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... 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...


It is clear that the spur gear design of reverse gear represents some compromises—less robust, unsynchronized engagement and loud noise—which are acceptable due to the relatively small amount of driving that takes place in reverse. However, many modern transmissions now include a reverse gear synchronizer and helical gearing.


Design Variations

Gear Variety

Manual transmissions are often equipped with 4, 5, or 6 forward gears. Nearly all have one reverse gear. In three or four speed transmissions, in most cases, the topmost gear is "direct", i.e. a 1:1 ratio. For five speed or higher transmissions, the highest gear is usually an overdrive gear, with a ratio of less than 1:1. Older cars were generally equipped with 3-speed transmissions, or 4-speed transmissions for high performance models and 5-speeds for the most sophisticated of automobiles; in the 1970s, 5-speed transmissions began to appear in low priced mass market automobiles and even compact pickup trucks, pioneered by Toyota (who advertised the fact by giving each model the suffix SR5 as it acquired the fifth speed). Today, mass market automotive manual transmissions are essentially all 5-speeds, with 6-speed transmissions beginning to emerge in high performance vehicles in the early 1990s, and recently beginning to be offered on some high-efficiency and conventional passenger cars. A very small number of 7-speed 'manual derived' transmissions are offered on extremely high-end performance cars (supercars), such as the Bugatti Veyron 16.4, or the BMW M5. Both of these cars feature a "Paddle Shifter". An overdrive is sometimes a separate unit that fits into the back of a gearbox, as with this Fairey unit. ... The 1970s decade refers to the years from 1970 to 1979, also called The Seventies. ... This article is about the automaker. ... For the band, see 1990s (band). ... For other uses, see Supercar (disambiguation). ... Semi-automatic transmission, or also known as clutchless manual transmission, automated manual transmission, e-gear, or paddle shift gearbox is a system which uses electronic sensors, processors and actuators to do gear shifts on the command of the driver. ...


External Overdrive

On earlier models with three or four forward speeds, the lack of an overdrive ratio for relaxed and fuel-efficient highway cruising was often filled by incorporating a separate overdrive unit in the rear housing of the transmission. This unit was separately actuated by a knob or button, often incorporated into the gearshift knob. An overdrive is sometimes a separate unit that fits into the back of a gearbox, as with this Fairey unit. ...


Shaft and Gear Configuration

The input shaft need not turn a pinion which rotates the countershaft. Another possibility is that gears are mounted on the input shaft itself, meshed with gears on the countershaft, in which case the countershaft then turns the output shaft. In other words, it's a matter of design on which shaft the driven and driving gears reside.


The distribution of the shifters is also a matter of design; it need not be the case that all of the free-rotating gears with selectors are on one shaft, and the permanently splined gears on the other. For instance a five speed transmission might have the first-to-second selectors on the countershaft, but the third-to-fourth selector and the fifth selector on the mainshaft, which is the configuration in the 1998 Honda Civic. This means that when the car is stopped and idling in neutral with the clutch engaged input shaft spinning, the third, fourth and fifth gear pairs do not rotate. The Honda Civic is a compact car manufactured by Honda. ...


In some transmission designs (Volvo 850 and V/S70 series, for example) there are actually two countershafts, both driving an output pinion meshing with the front-wheel-drive transaxle's ring gear. This allows the transmission designer to make the transmission narrower, since each countershaft must be only half as long as a traditional countershaft with four gears and two shifters.


Clutch

In all vehicles using a transmission (virtually all modern vehicles), a coupling device is used to separate the engine and transmission when necessary. The clutch accomplishes this in manual transmissions. Without it, the engine and tires would at all times be inextricably linked, and anytime the vehicle was at a stop, the engine would be forced to a stall. Without the clutch, changing gears would be very difficult, even with the vehicle moving already: deselecting a gear while the transmission is under load requires considerable force, and selecting a gear requires the revolution speed of the engine to be held at a very precise value which depends on the vehicle speed and desired gear. In a car the clutch is usually operated by a pedal; on a motorcycle, a lever on the left handlebar serves the purpose. For other uses, see Clutch (disambiguation). ...

Pedal setup on a 2007 Subaru Legacy. From left to right, the dead pedal, clutch pedal, brake, and accelerator.
Pedal setup on a 2007 Subaru Legacy. From left to right, the dead pedal, clutch pedal, brake, and accelerator.
  • When the clutch pedal is fully depressed, the clutch is fully disengaged, and no torque is transferred from the engine to the transmission, and by extension to the drive wheels. In this state, it's possible to select gears or stop the car.
  • When the clutch pedal is fully released, the clutch is fully engaged, and essentially all of the engine's torque is transferred. In this state, the clutch does not slip, but rather behaves like a rigid coupling. Power is transmitted to the wheels with minimal loss.
  • In between these extremes, the clutch slips to varying degrees. When the clutch slips, it transmits torque, in spite of the difference in speeds between the engine crankshaft and the transmission input. Because the torque is transmitted by means of friction, a lot of power is wasted as heat, which must be dissipated by the clutch. Slip allows the vehicle to be started from a standstill, and when it is already moving, slip allows the engine rotation to gradually adjust to a newly selected gear ratio, resulting in a smooth, jolt-free gear change.
  • Because of the heat that a slipping clutch generates, slip cannot be maintained for a long time. Moreover, because energy is wasted, it would be undesirable to do so. Skilled drivers rarely allow a clutch to slip for more than about one second. Making effective use of clutch slip requires the development of feeling through practice, similar to learning to play a musical instrument or to play a sport.
  • A rider of a highly-tuned motocross or off-road motorcycle may "hit" or "fan" the clutch when exiting corners to assist the engine in revving to point where it makes the best power.
  • Note: Automatic transmissions also use a coupling device, however, a clutch is not present. In these kinds of vehicles, the torque converter is used to separate the engine and transmission.

Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (2048 × 1536 pixel, file size: 851 KB, MIME type: image/jpeg) Photo showing the pedals of my car for use in the article on manual transmissions. ... Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (2048 × 1536 pixel, file size: 851 KB, MIME type: image/jpeg) Photo showing the pedals of my car for use in the article on manual transmissions. ... The Legacy is a mid-size car introduced by the Japanese manufacturer Subaru in February 1989 as a larger, upscale companion to the companys Leone/Loyale and currently serves as the flagship model in the Subaru range. ... 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. ... ZF torque converter A cut-away model of a torque converter A torque converter is a modified form of a hydrodynamic fluid coupling, and like the fluid coupling, is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating...

Gear selection

Floor-mounted shifter

In most modern cars, gears are selected through a lever attached to the floor of the automobile—this selector is often called a gearstick, gear lever, gear selector, or simply shifter. Moving this lever forward, backward, left, and right allows the driver to select any given gear. In this configuration, the gear lever must be pushed laterally before it is pushed longitudinally. A gear stick (also gearstick, gear lever and gear shifter) is the lever used to change gear in a vehicle, such as an automobile, with manual transmission or automatic transmission. ...

5 speed shift stick of a 1999 Mazda Protege.
5 speed shift stick of a 1999 Mazda Protege.

A sample layout of a four-speed transmission is shown below. N marks neutral, or the position where no gears are engaged. In reality, the entire horizontal line is a neutral position, although the shifter is usually equipped with springs so that it will return to the N position if not left in another gear. The R denotes reverse, which is technically a fifth gear on this transmission. Image File history File links Download high resolution version (1500x1125, 284 KB) Summary Gear shift stick of my Mazda Protege SE 1999. ... Image File history File links Download high resolution version (1500x1125, 284 KB) Summary Gear shift stick of my Mazda Protege SE 1999. ... The Mazda 323 (called the Mazda Familia in Japan) was a subcompact car produced by Mazda in Japan between 1976 and 2003. ...


Image File history File links Manual_Layout4d. ...


This layout is called the shift pattern. Because of the shift quadrants, the basic arrangement is often called an H-pattern. While the layout for gears one through four is nearly universal, the location of reverse is not. Reverse can be found outside of the quadrant at the upper left (late 1960s GM models and AMC models, 1960s-1980s Ford Europe models, and current VW/Audi models), lower left (Toyota Land Cruiser FJ, Ferrari), the lower right (Jeep CJ7, Datsun models, and Honda Civic), or upper right (Corvette), so caution is always warranted in gear selection. The shift pattern for a specific transmission is usually molded on the gear knob. General Motors Corporation (NYSE: GM), also known as GM, is an American automobile maker with worldwide operations and brands including Buick, Cadillac, Chevrolet, GMC, Holden, Hummer, Opel, Pontiac, Saturn, Saab and Vauxhall. ... This article is about the automaker. ... This article needs cleanup. ... For other uses, see Ferrari (disambiguation). ... The Honda Civic is a compact car manufactured by Honda. ... French steam corvette Dupleix (1856-1887) Canadian corvettes on antisubmarine convoy escort duty during World War II. A corvette is a small, maneuverable, lightly armed warship, smaller than a frigate but larger than a coastal patrol craft. ... A gear stick (also gearstick, gear lever, selection lever, and gear shifter) is the lever used to change gear in a vehicle, such as an automobile, with manual transmission or automatic transmission. ...


The image below shows the most common five-speed layout found in the USA and the UK.


Image:Manual Layout.PNG Image File history File links Manual_Layout. ...


This layout is reasonably intuitive because it starts at the upper left and works top to bottom, left to right, with reverse far away and toward the rear of the car. There is usually a mechanism that only allows selection of reverse from the neutral position, so reverse will be less likely to be accidentally chosen when downshifting from 5th to 4th (or by someone used to a 6-speed transmission and trying to shift from 5th to the non-existent 6th).


Image File history File links Manual_Dogleg. ...


This five-speed layout, found on a number of older models and race cars, is commonly referred to as a "dog-leg first" or "racing" pattern, because of the "up and over" 1-2 shift. Its use was common on race cars and sports cars in the days before six and seven speed transmissions. By putting 4th and 5th on the same vertical plane, shifting at high speed becomes easier and faster. Conversely, the long, offset 1-2 shift can have a notable effect on a car's initial acceleration, especially in 0-60 mph time tests.


This gear pattern can also be found on some heavy vehicles where 1st gear is a crawler gear and would see little normal use.


Another five-speed shift pattern (common on many European cars) is this:


Image File history File links Manual_Layout_2. ...


Transmissions equipped with this shift pattern usually feature a lockout mechanism that requires the driver to depress a switch or the entire gear lever when entering reverse, so that reverse is not accidentally selected when trying to find first gear. This style of pattern (including depressing the gear lever) is common on BMWs, Opels, most Volkswagens (though some have reverse towards second gear,) older Volvo 240s and some Renault models (12, 9, 19, 5, Mégane, Twingo and Clio).


A typical pattern for the more modern six-speed transmission is shown here


Image:Manual Layout6.png Image File history File links Manual_Layout6. ...


A six-speed manual transmission (seven speeds with reverse) is widely considered to be the largest number of gears that can be contained within a variation of the "H" shift pattern. Note that reverse is placed outside of the "H", with a canted shift leg. This is to prevent the shift lever from intruding too far into the driver's footwell (in left-hand drive cars) when reverse is selected. This is the most common layout for a six-speed manual transmission.  drive on right drive on left Driving on either the left or the right side of the road prevents vehicles moving in opposite directions from colliding with each other. ...


Most front-engined, rear-wheel drive cars have a transmission that sits between the driver and the front passenger seat. Floor-mounted shifters are often connected directly to the transmission. Front-wheel drive and rear-engined cars often require a mechanical linkage to connect the shifter to the transmission. In automobile design, an FR, or front-engine, rear wheel drive means a layout where the engine is in the front of the vehicle and drive wheels at the rear. ... In automobile design, an FF, or Front-engine, Front wheel drive, layout places both the engine and driven wheels at the front of the vehicle. ... This article does not cite any references or sources. ...


Historically, 4-speed floor shifters were sometimes referred to as "Four on the Floor", when steering column mounted shifters were more common.


Column-mounted shifter

Some cars have a gear lever mounted on the steering column of the car. It was common in the past but is no longer common today. However, many automatic transmissions still use this placement.


Column shifters are mechanically similar to floor shifters, although shifting occurs in a vertical plane instead of a horizontal one. Column shifters also generally involve additional linkages to connect the shifter with the transmission. Also, the pattern is not "intuitive," as the shifter has to be moved backward and upward into R to make the car go backward. Intuition has many meanings across many cultures, including: quick and ready insight seemingly independent of previous experiences and empirical knowledge immediate apprehension or cognition knowledge or conviction gained by intuition the power or faculty of attaining to direct knowledge or cognition without evident rational thought and inference. ...


A 3-speed column shifter, nicknamed "Three on the Tree" (alternatively, "Three in the Tree"), began appearing in America in the late 1930s and became common during the 1940s and 50's. Its layout is as shown below:


Image:Manual Layout 3.PNG Image File history File links Manual_Layout_3. ...


First gear in a 3-speed is often called "low," while third is usually called "high." There is, of course, no overdrive. Later European and Japanese models began to have 4-speed column shifter and some of these made their way to the USA. Its layout is shown here:


Image:Column4MT.PNG Image File history File links Column4MT.PNG‎ Four speed manual transmission column-mounted shifter pattern. ...


However, the column manual shifter disappeared in America by the late 1970s. But in the rest of the world, the column mounted shifter continued to be made, and was in fact common in some places. For example, all Toyota Crown and Nissan Cedric taxis in Hong Kong had the 4-speed column shift until 1999 when automatic began to be offered. Since the late 1980s or early 1990s, 5-speed column shifter has been made in some vans sold in Asia and Europe, such as Toyota Hiace and Mitsubishi L400. The Toyota Crown is a line of full-size luxury sedans by Toyota. ... The Nissan Cedric is a large luxurious automobile produced by Nissan since 1960. ... An urban red taxi in Hong Kong. ... The Toyota Hiace is an automobile that was first produced by the Toyota Motor Corporation in 1967. ... This page meets Wikipedias criteria for speedy deletion. ...


Sequential manual

Some transmissions do not allow the driver to arbitrarily select any gear. Instead, the driver may only ever select the next-lowest or next-highest gear ratio. These transmissions often provide clutch control, but the clutch is only necessary when selecting first or reverse gear from neutral. Most gear changes can be performed without the clutch.


Sequential transmissions are generally controlled by a forward-backward lever, foot pedal, or set of paddles mounted behind the steering wheel. In some cases, these are connected mechanically to the transmission. In many modern examples, these controls are attached to sensors which instruct a transmission computer to perform a shift—many of these systems can be switched into an automatic mode, where the computer controls the timing of shifts, much like an automatic transmission. The automatic gear selector in a Ford Five Hundred vehicle An automatic transmission is an automobile gearbox that can change gear ratios automatically as the vehicle moves, thus freeing the driver from having to shift gears manually (similar but larger devices are also used for railroad locomotives). ...


Motorcycles typically employ sequential transmissions, although the shift pattern is modified slightly for safety reasons. In a motorcycle the gears are usually shifted with the left foot pedal, the layout being this:

The gear shift lever on a 2003 Suzuki SV650S motorcycle.

            6
         5 ┘
      4 ┘
    3 ┘
  2 ┘
N
1
Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (2048 × 1536 pixel, file size: 847 KB, MIME type: image/jpeg) Photo of the gearshift on my motorcycle, for use in the article on manual transmissions. ... Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (2048 × 1536 pixel, file size: 847 KB, MIME type: image/jpeg) Photo of the gearshift on my motorcycle, for use in the article on manual transmissions. ... 2006 Suzuki SV650S 2002 Suzuki SV650 2004 Suzuki SV650 Suzuki introduced the SV650 in 1999 as a budget entry in the emerging naked bike market. ...


The pedal goes one step - both up and down - from the center, before it reaches its limit and has to be allowed to move back to the center position. Thus, changing multiple gears in one direction is accomplished by repeatedly pumping the pedal, either up or down. Although neutral is listed as being between first and second gears for this type of transmission, it "feels" more like first and second gear are just "further away" from each other than any other two sequential gears. Because this can lead to difficulty in finding neutral for inexperienced riders most motorcycles have a neutral indicator light on the instrument panel to help finding the neutral gear. The reason neutral does not actually have its own spot in the sequence is to make it quicker to shift from first to second when moving. You will not accidentally shift into neutral. The reason for having neutral between the first and second gears instead of at the bottom is that when stopped, the rider can just click down repeatedly and know that they will end up in first and not neutral.


On motorcycles used on race tracks, the shifting pattern is often reversed, that is, the rider clicks down to upshift. This usage pattern increases the ground clearance by placing the riders foot above the shift lever when the rider is most likely to need it, namely when leaning over and exiting a tight turn. Ride height (ground clearance or simply clearance) is the amount of space between the base of an automobile tyre and the underside of the chassis; or, more properly, to the shortest distance between a flat, level surface, and any part of a vehicle other than those parts designed to contact...


The shift pattern for most underbone motorcycles with automatic centrifugal clutch is also modified for 2 key reasons - to enable the less-experienced riders to shift the gears without problems of "finding" the neutral gear, and also due to more force needed to "lift" the gearshift lever (because gearshift pedal of an underbone motorcycle also operates the clutch). The gearshift lever of an underbone motorcycle has two ends, therefore the rider clicks down the front end with the left toe all the way to the top gear and clicks down the rear end with the heel all the way down to neutral. Some underbone models such as Honda Wave have "rotary" shift pattern, which means that the rider can shift directly to neutral from the top gear, but this is only possible when the motorcycle is stationary for safety reasons. Some models also have gear position indicators for all gear positions at the instrument panel. Modern underbones use plastic cover sets, allowing users to customize their bikes easily such like this Modenas Kriss 2. ... There are very few or no other articles that link to this one. ... Honda Wave series, also known as Honda NF series, Honda Innova (in Europe), and Honda Supra (in Indonesia) is a series of small motorcycle models (known as moped or kapchai) manufactured by Honda Motor Co. ...


Semi-manual

Some new transmissions (Fiat's Selespeed gearbox and BMW's Sequential Manual Gearbox (SMG) for example) are conventional manual transmissions with a computerized control mechanism. These transmissions feature independently selectable gears but do not have a clutch pedal. Instead, the transmission computer controls a servo which disengages the clutch when necessary. Fiat S.p. ... For other uses, see BMW (disambiguation). ... For other uses, see Clutch (disambiguation). ... Look up servo in Wiktionary, the free dictionary. ...


These transmissions vary from sequential transmissions in that they still allow nonsequential shifts: BMWs SMG system, for example, can shift from 6th gear directly to 4th gear when decelerating from high speeds.


Comparison with automatic transmissions

Manual transmissions are typically compared to automatic transmissions, as the two represent the majority of options available to the typical consumer. These comparisons are general guidelines and may not apply in certain circumstances. Additionally, the recent popularity of semi-manual and semi-automatic transmissions renders many of these points obsolete. It should be kept in mind that some of these points are true of "conventional" automatic transmissions which shift gears and are coupled to the engine with a torque converter but are not a true comparison or do not apply to other kinds of automatic transmissions, like the continuously-variable transmission. An automatic transmission is an automobile gearbox that can change gear ratios automatically as the car moves, thus freeing the driver from having to shift gears United States since the 1950s have had automatic transmissions. ... Semi-automatic transmission, or also known as clutchless manual transmission, automated manual transmission, e-gear, or paddle shift gearbox is a system which uses electronic sensors, processors and actuators to do gear shifts on the command of the driver. ... ZF torque converter A cut-away model of a torque converter A torque converter is a modified form of a hydrodynamic fluid coupling, and like the fluid coupling, is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating... A continuously variable transmission (CVT) is a type of automatic transmission that can change the gear ratio (gears are not generally involved) to any arbitrary setting within the limits. ...


Advantages

  • Manual transmissions typically offer horrible fuel economy compared to automatics.[2] Increased fuel economy with a properly operated manual transmission vehicle versus an equivalent automatic transmission vehicle can range from 5% to about 15% depending on driving conditions and style of driving -- extra urban or urban (highway or city). There are several reasons for this:
    • Mechanical efficiency. The manual transmission couples the engine to the transmission with a rigid clutch instead of a torque converter that introduces significant power losses. The automatic transmission also suffers parasitic losses by driving the high pressure hydraulic pumps required for its operation.
    • Driver control. Certain fuel-saving modes of operation simply do not occur in an automatic transmission vehicle, but are accessible to the manual transmission driver. For example, the manual-transmission vehicle can be accelerated gently, yet at wide open throttle (WOT), by means of shifting early to a higher gear, keeping the engine RPM in a low power band. By contrast, in an automatic transmission, the throttle position serves as the indicator of how fast the driver wishes to accelerate. If the accelerator pedal is floored, the transmission will shift to a lower gear, resulting in high engine RPM and aggressive acceleration. The thermodynamically efficient combination of open throttle and low RPMs is unavailable to the automatic transmission driver. Fuel-efficient acceleration is important to achieving fuel economy in stop-and-go city driving.[3]
    • Fuel cut-off. The torque converter of the automatic transmission is designed for transmitting power from the engine to the wheels. Its ability to transmit power in the reverse direction is limited. During deceleration, if the torque converter's rotation drops beneath its stall speed, the momentum of the car can no longer turn the engine, requiring the engine to be idled. By contrast, a manual transmission, with the clutch engaged, can use the car's momentum to keep the engine turning, in principle, all the way down to zero RPM. This means that there are better opportunities, in a manual car, for the electronic control unit (ECU) to impose deceleration fuel cut-off (DFCO), a fuel-saving mode whereby the fuel injectors are turned off if the throttle is closed (foot off the accelerator pedal) and the engine is being driven by the momentum of the vehicle. Automatics further reduce opportunities for DFCO by shifting to a higher gear when the accelerator pedal is released, causing the RPM to drop.[citation needed]
    • Geartrain efficiency. Automatics may require power to be transmitted through multiple planetary gearsets before attaining the desired gear ratio. In comparison, manual transmissions usually transmit power through one or two gearsets at most.[citation needed]
  • Manual transmissions are still less efficient than belt-driven continuously-variable transmissions.[4][5]
  • Manual transmissions are generally significantly heavier than torque-converter automatics.[2]
  • Vehicles with manual transmissions are typically more expensive than those with automatic transmissions.
  • Manual transmissions generally require more maintenance than automatic transmissions.[citation needed]
  • Manual transmissions normally do require active cooling, because not much power is dissipated as heat through the transmission.[5]
    • The heat issue can be important in certain situations, like climbing long hills in hot weather, particularly if pulling a load. Unless the automatic's torque converter is locked up (which typically only happens in an overdrive gear that would not be engaged when going up a hill) the transmission can overheat.[6] A manual transmission's clutch only generates heat when it slips, which does not happen unless the driver is riding the clutch pedal.
  • A driver has more direct control over the state of the transmission with a manual than an automatic. This control is important to an experienced, knowledgeable driver who knows the correct procedure for executing a driving maneuver, and wants the machine to realise his or her intentions exactly and instantly. Manual transmissions are particularly advantageous for performance driving or driving on steep and winding roads. Note that this advantage applies equally to manual-automatic transmissions, such as tiptronic, provided they have a quick reaction time to driver input.
    • An example: the driver, anticipating a turn, can downshift to the appropriate gear while the steering is still straight, and stay in gear through the turn. This is the correct, safe way to execute a turn. An unanticipated change of gear during a sharp turn can cause skidding if the road is slippery.
    • Another example: when starting, the driver can control how much torque goes to the tires, which is useful for starting on slippery surfaces such as ice, snow or mud. This can be done with clutch finesse, or possibly by starting in second gear instead of first. The driver of an automatic can only put the car into drive, and play with the throttle. The torque converter can easily dump too much torque into the wheels, because when it slips, it acts as an extra low gear, passing through the engine power, reducing the rotations while multiplying torque. An automatic equipped with ESC, however, does not have this disadvantage.[citation needed] Some cars, such as the Saab NG900 Automatic transmission, have a special mode for low traction situations.
    • Yet another example: passing. When the driver is attempting to pass a slower moving vehicle by making use of a lane with opposite traffic, he or she can select a lower gear for more power at exactly the right moment when conditions are right to begin the maneuver. Automatics have a delayed reaction time, because the driver can only indicate his intent by pressing the throttle. The skilled manual transmission driver has an advantage of superior finesse and confidence in such situations.
  • Driving a manual requires more involvement from the driver, thereby discouraging some dangerous practices. The manual selection of gears requires the driver to monitor the road and traffic situation, anticipate events and plan a few steps ahead. If the driver's mind wanders from the driving task, the machine will soon end up in an incorrect gear, which will be obvious from excessive or insufficient engine RPM. Related points:
    • It's much more difficult for the driver to fidget in a manual transmission car, for instance by eating, drinking beverages, or talking on a cellular phone without a headset. During gear shifts, two hands are required. One stays on the wheel, and the other operates the gear lever. The hand on the wheel is absolutely required during turns, and tight turns are accompanied by gear changes. If the hand leaves the wheel, the steering will begin to straighten. In general, the more demanding the driving situation, the more difficult it is for the manual driver to do anything but operate the vehicle. The driver of an automatic transmission can engage in distracting activities in any situation, such as sharp turns through intersections or stop-and-go traffic.
    • The driver of a manual transmission car can develop an accurate intuition for how fast the car is traveling, from the sound of the motor and the gear selection. It's easier to observe the lower speed limits—like 30 km/h and 50 km/h or their U.S. and Imperial counterparts, 20 mph and 30 mph—without glancing at the instrumentation.
  • Cars with manual transmissions can often be started when the battery is dead by pushing the car into motion or allowing it to roll downhill, and then engaging the clutch in third or second gear. This is commonly known as a "push start", "popping the clutch" (in the USA), "crash starting" (in New Zealand), or Bump starting in the UK , describes the action of suddenly releasing the clutch pedal after putting it in gear. Note that this is not always possible with a truly dead battery due to theft-deterrent mechanisms and steering wheel locks. If not, a potential thief could drain the battery then push-start the vehicle.
  • Manual transmissions work regardless of the orientation angle of the car with respect to gravity. Automatic transmissions have a fluid reservoir (pan) at the bottom; if the car is tilted too much, the fluid pump can be starved, causing a failure in the hydraulics. This could matter in some extreme off roading circumstances where gravity pulls the fluid away from the reservoir, or when high cornering forces force the fluid to pool on one side.[citation needed]
  • It is sometimes possible to move a vehicle with a manual transmission just by putting it in gear and cranking the starter. This is useful in an emergency situation where the vehicle will not start, but must be immediately moved (from an intersection or railroad crossing, for example). It is also easier to put a car with a manual transmission into neutral, even when the transmission has suffered damage from an accident or malfunction. Many modern vehicles will not allow the starter to be run without the clutch fully depressed, negating this advantage, but some manufacturers have begun to add a clutch start override switch so that this advantage may still be enjoyed when necessary.

ZF torque converter A cut-away model of a torque converter A torque converter is a modified form of a hydrodynamic fluid coupling, and like the fluid coupling, is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating... Wide Open Throttle (WOT) refers to an internal combustion engines maximum intake of air and fuel that occurs when the throttle plates inside the carburetor or throttle body are wide open, providing the least resistance to the incoming air. ... In a vehicle with a manual transmission, riding the clutch refers to the practice of keeping the clutch partially disengaged when not required. ... Electronic Stability Control (ESC) is the generic term for systems designed to improve a vehicles handling, particularly at the limits where the driver might lose control of the vehicle. ... For other uses, see Saab (disambiguation). ... The U.S. customary units (more commonly known in the US as English units or standard units) are the non-metric units of measurement that are presently used in the United States, in some cases alongside the metric system of units. ... The Imperial units or the Imperial system is a collection of English units, first defined in the Weights and Measures Act of 1824, later refined (until 1959) and reduced. ... Bump starting also known as push starting is the process of starting an internal combustion engine - typically in a motor vehicle - with out the use of the starter motor. ...

Disadvantages

Many of the disadvantages of a manual transmission involve the driver interaction with the vehicle. While most of these can be overcome with practice and experience, they should be considered:

  • Manual transmissions often require the driver to place their full and continuous attention on operating the vehicle, which may be seen as a disadvantage. Many, though, consider this an advantage, as it prevents the driver from other potential distractions like mobile phone or radio use.
  • Inexperienced drivers may place more of their attention on shifting the gears of the transmission, potentially distracting them from the road surroundings.
  • A driver may inadvertently shift into the wrong gear with a manual transmission, potentially causing damage to the engine or transmission. It may also result in loss of control due to a sudden change in the vehicle's speed. However, some of this can be offset with a lockout on the reverse such as those found on many European cars.
  • Manual transmissions require a learning curve as one must develop a feel for properly engaging the clutch.
  • While it can easily be overcome with experience, manual transmission vehicles require good accelerator pedal application and clutch control when starting the car from a standstill. Excessive RPMs may cause the car to redline, exacerbating engine wear, whereas insufficient RPMs upon clutch release causes the engine to stall due to the lack of momentum required to sustain engine operation.
  • The smooth and quick shifts of an automatic transmission are not guaranteed when operating a manual transmission; such changes are dependent on the driver's experience and timing.
  • Manual transmissions burden the driver in heavy traffic situations since the driver is seemingly too often operating the clutch pedal. In comparison, automatic transmissions merely require moving the foot from the accelerator pedal to the brake pedal, and vice versa.
  • For a person with physical impairment, an automatic transmission might be the only available shifting option. The comparable systems for hand-operated clutch and brakes for a manual-transmission-equipped car are usable only by people with just lower body handicap. Retrofit of such a system also requires extensive modifications to the car.
  • Vehicles with manual transmissions are more difficult to start from a rest when positioned upward on a hill as it requires coordination of the accelerator, the clutch pedals, and the handbrake. This can be easily feasible, however, with experience.
  • The clutch disc, with the exception of kevlar clutch discs, wears, and therefore must be replaced periodically. While this is typically a labor intensive process that can be an expensive service, it should not prove more expensive than periodic service to an automatic gearbox in the long run. How long the clutch lasts (and therefore the cost relative to servicing an automatic transmission) is highly dependent on the skill and driving style of the operator.

Kevlars molecular structure; BOLD: monomer unit; DASHED: hydrogen bonds. ...

Applications and popularity

Many types of automobiles are equipped with manual transmissions. Small economy cars predominantly feature manual transmissions because they are relatively cheap and efficient, although many are or may be optionally equipped with automatics. Economy cars are also often powered by very small engines, and automatic transmissions can make them comparatively very slow, while a manual transmission makes much more efficient use of the power produced.


Sports cars are also often equipped with manual transmissions because they offer more direct driver involvement and better performance. Off-road vehicles and trucks often feature manual transmissions because they allow direct gear selection and are often more rugged than their automatic counterparts.


Conversely, manual transmissions are no longer popular in many classes of cars sold in North America and Japan, although they remain dominant in Europe. Nearly all cars are available with an automatic transmission option, and family cars and large trucks sold in the US are predominantly fitted with automatics. In Europe and Asia (except Japan) most cars are sold with manual transmissions. Most luxury cars are only available with an automatic transmission. In situations where automatics and manual transmissions are sold side-by-side, the manual transmission is the base equipment, and the automatic is optional—although the automatic is sometimes available at no extra cost. Some cars, such as rental cars and taxis, are nearly universally equipped with automatic transmissions in countries such as the US, but the opposite[dubious ] is true in Europe. Rental cars are generally recent model cars that are available, in exchange for a fee, for periods typically ranging from a day to a week or longer. ... For specific countries see Taxicabs around the world. ... For other uses, see Europe (disambiguation). ...


In some countries, such as the United Kingdom, Israel, Ireland, Switzerland, Germany, Austria, The Netherlands, Greece, Sweden, Japan, Belgium, Finland, Singapore, Australia, the United Arab Emirates and New Zealand, when a driver takes the licencing road test using an automatic transmission, the resulting licence is restricted to the use of automatic transmissions. This treatment of the manual transmission skill seems to maintain the widespread use of the manual transmission, as many new drivers worry that their restricted licence will become an obstacle for them where most cars have manual transmissions, so they make the effort to learn with manual transmissions and obtain full licenses. Some other countries (such as Pakistan and China) go even further, whereby the licence is granted only when a test is passed on a manual transmission. Motto: Je Maintiendrai (Dutch: Ik zal handhaven, English: I Shall Uphold) Anthem: Wilhelmus van Nassouwe Capital Amsterdam1 Largest city Amsterdam Official language(s) Dutch2 Government Parliamentary democracy Constitutional monarchy  - Queen Beatrix  - Prime minister Jan Peter Balkenende Independence Eighty Years War   - Declared July 26, 1581   - Recognised January 30, 1648 (by Spain... The automatic gear selector in a Ford Five Hundred vehicle An automatic transmission is an automobile gearbox that can change gear ratios automatically as the vehicle moves, thus freeing the driver from having to shift gears manually (similar but larger devices are also used for railroad locomotives). ...


Truck transmissions

Very heavy trucks also feature manual transmissions because they are efficient and, more importantly, can withstand the severe stress encountered in hauling heavy loads.


Most companies with fleets of large trucks use 10 speed non-synchronized manual transmissions, because their shift patterns are simpler to learn than the super-10 and 13 speed transmissions. The shift pattern for a standard 10-speed transmission on a truck, such as the Eaton-Fuller RoadRanger 10 speed, is the same as a 5 speed standard in a passenger car. There is a high-low selector switch on the gear shift itself, and after going through 5th gear, which is approximately 15 MPH though it may be geared differently, the switch is flipped up, and the shifter moved back to the first gear position, which is now 6th gear. This causes Reverse to have a HIGH reverse also, which will allow the vehicle to move at speeds up to 25 MPH in reverse, and is definitely not recommended.


To start a large truck moving from a standstill, with the engine started and the transmission in neutral, the clutch pedal must be pressed all the way to the floor to engage the clutch brake. The service brakes should also be applied. Once the clutch brake is engaged, the shifter is moved to the low/1st gear, and the clutch and brakes can be released. It is VERY important to note that a heavy-duty truck engine is capable of producing over 1500 foot-pounds of torque and can destroy a clutch fairly easily, so the throttle should not be touched until the clutch pedal is completely released. Giving the vehicle throttle while the clutch is not fully engaged will do nothing more than make the clutch slip, and wont actually help move the vehicle at all, while at the same time overheating the clutch.


However, Automated Manual Transmissions (AMT's) and semi-automatic transmissions are becoming more common on heavy vehicles, particularly in the European market. Mercedes-Benz is one of the manufacturers leading the introduction of AMT and semi-automatic gearboxes. This has been closely followed by other leading truck manufacturers, such as MAN, Scania, Volvo, and DAF. The use of fully automatic gearboxes is more common on buses, with Voith and Allison being the leading manufacturers of heavy automatic gearboxes, the use of this type of transmission is also common in specialist vehicles, such as fire appliances and municipal vehicles (road-sweepers, refuse collection vehicles, etc.). This page is about the Mercedes-Benz brand of automobiles and trucks from the DaimlerChrysler automobile manufacturer. ... MAN AG (formerly called Maschinenfabrik Augsburg-Nürnberg AG, ISIN: DE0005937007) is a German transportation company. ... A vintage Scania truck (L80 successor to the Scania-Vabis L56) Scania A1 1901 Scania Type A Tonneau 1903 Scania AB is a leading European manufacturer of heavy trucks (British English: lorries), buses, and diesel engines, based in Södertälje, Sweden. ... Volvo Trucks, a Swedish truck manufacturer, owned by Volvo, is the Worlds second largest heavy-duty truck brand. ... DAF Trucks NV is a Dutch truck manufacturing company and a division of PACCAR. Its headquarters and main plant are in Eindhoven. ... The Voith-Schneider propeller is a specialized marine propulsion system. ... Allison Transmission is a manufacturer of automatic transmissions for medium and heavy-duty commercial vehicle applications. ...


Maintenance

Because clutches use changes in friction to modulate the transfer of torque between engine and transmission, they are subject to wear in everyday use. A very good clutch, when used by an expert driver, can last hundreds of thousands of kilometres (or miles). Weak clutches, abrupt downshifting, inexperienced drivers, and aggressive driving can lead to more frequent repair or replacement. For other uses, see Friction (disambiguation). ... “km” redirects here. ...


Manual transmissions are lubricated with gear oil, which must be changed periodically in some cars, although not as frequently as the automatic transmission fluid in a vehicle so equipped. (Some manufacturers specify that changing the gear oil is never necessary except after transmission work or to rectify a leak.)


Gear oil has a characteristic aroma due to the addition of molybdenum disulfide compounds. These compounds are used to reduce the high sliding friction by the helical gear cut of the teeth (this cut eliminates the characteristic whine of straight cut spur gears). Some manufacturers, however, such as Honda, do not use this additive in their gear lube, specifying regular motor oil until recently, and now their own brand of gear lube which seems to be an enhanced version of motor oil. On motorcycles with "wet" clutches (clutch is bathed in engine oil), there is usually nothing separating the lower part of the engine from the transmission, so the same oil lubricates both the engine and transmission. Molybdenum disulfide, also called molybdenum sulfide or molybdenum(IV) sulfide, with the formula MoS2, is a black crystalline sulfide of molybdenum. ... Sliding friction is when two objects are rubbing against each other. ... Spur gears found on a piece of farm equipment. ... Spur gears found on a piece of farm equipment. ... This article is about the Japanese motor corporation. ... // A typical container of motor oil, with some in a glass. ... // A typical container of motor oil, with some in a glass. ...

See also

The T-56 six speed manual transmission has been used in a wide range of vehicles from General Motors, Dodge, and Ford Motor Company. ... Toploader 4 speed for a Ford Mustang A Toploader transmission is a manually actuated three and four speed gearbox introduced in 1964 by Ford Motor Company to replace the BorgWarner T-10. ...

Suggested other reading

gear ratio
non-synchronous transmissions
transmission (mechanics) Gears on a piece of farm equipment, gear ratio 1:1. ... Non-synchronous transmission is a form of transmission system based on gears that do not use synchronizing mechanisms. ... “Gearbox” redirects here. ...


References

  1. ^ Synchronizers; graphic illustration of how they work. Retrieved on 2007-07-18.
  2. ^ a b The United States Department of Energy website is dedicated to providing information about the fuel consumption of many makes and models of vehicles, with separate entries for the manual and automatic transmission variants of a model, if they exist. The site's Transmission Technologies page states that "Manual transmissions are lighter than conventional automatic transmissions and suffer fewer energy losses."
  3. ^ For more information, see the BSFC page:
    A reciprocating engine achieves maximum efficiency at torque-peak speed and wide-open throttle.
  4. ^ An Investigation into The Loss Mechanisms associated with a Pushing Metal V-Belt Continuously Variable Transmission, Sam Akehurst, 2001, Ph. D Thesis, University of Bath.
    Despite these theoretical predictions to date reduced fuel consumptions and emissions have not been realised by production cars fitted with CVTs. Rather fuel economy figures compared to equivalent fixed ratio vehicles have been at best equal and in most cases considerably lower. (p. 1-2)
  5. ^ a b An Overview of Current Automatic, Manual and Continuously Variable Transmission Efficiencies and Their Projected Future Improvements, Kluger and Log, SAE 1999-01-1259
    This publication assigns 94% efficiency to current 5 speed manual transmissions, 70-80% efficiency (city-highway) to a current four-speed automatics, and predicts 88% efficiency for future continuously-variable designs.
  6. ^ Car Repair and Maintenance on Yahoo
    Extended discusson about automatic transmission overheating issues.

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st Century. ... is the 199th day of the year (200th in leap years) in the Gregorian calendar. ... Brake Specific Fuel Consumption (BSFC) is a measure of an engines efficiency. ...

External links


  Results from FactBites:
 
Howstuffworks "How Manual Transmissions Work" (509 words)
The transmission allows the gear ratio between the engine and the drive wheels to change as the car speeds up and slows down.
The transmission is connected to the engine through the clutch.
A five-speed transmission applies one of five different gear ratios to the input shaft to produce a different rpm value at the output shaft.
  More results at FactBites »

 
 

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