Motor vehicle manual gearbox; stick shift

A manual manual (MT), also known as transmission gearbox, standard transmission (in Canada, the United Kingdom, and the United states), or stick shift (in the U.s.), is a multi-speed motor vehicle manual organization, where gear changes require the driver to manually select the gears by operating a gear stick and clutch (which is usually a human foot pedal for cars or a hand lever for motorcycles).

Early automobiles used sliding-mesh transmission transmissions with upward to three forward gear ratios. Since the 1950s, constant-mesh manual transmissions have become increasingly commonplace and the number of forward ratios has increased to 5-speed and half-dozen-speed manual transmissions for current vehicles.

The alternative to a manual transmission is an automatic manual; mutual types of automated transmissions are the hydraulic automatic transmission (AT), and the continuously variable transmission (CVT), whereas the automated manual manual (AMT) and dual-clutch transmission (DCT) are internally like to a conventional manual transmission, only are shifted automatically.

Alternately, at that place are transmissions which facilitate manual clutch functioning, only the driver'south input is withal required to manually change gears; namely semi-automatic transmissions. These systems are based on the design of a conventional manual transmission, with a gear shifter, and are mechanically similar to a conventional manual transmission, with the driver's control and input however required for manually changing gears (similar with a standard manual manual), simply the clutch system is completely automated, and the mechanical linkage for the clutch pedal is completely replaced by an actuator, servo, or solenoid and sensors, which operate the clutch system automatically, when the driver touches or moves the gearshift. This removes the need for a concrete clutch pedal.

Overview [edit]

A manual transmission requires the driver to operate the gear stick and clutch in guild to modify gears (different an automatic transmission or semi-automatic transmission, where one (typically the clutch) or both of these functions are automated). Most manual transmissions for cars allow the commuter to select any gear ratio at whatever time, for example shifting from second to 4th gear, or 5th to tertiary gear. However, sequential manual transmissions, which are commonly used in motorcycles and racing cars, only let the driver to select the next-higher or next-lower gear.

In a vehicle with a transmission transmission, the flywheel is attached to the engine's crankshaft, therefore rotating at engine speed. A clutch sits between the flywheel and the transmission input shaft, controlling whether the transmission is continued to the engine (clutch engaged- the clutch pedal is non being pressed) or not connected to the engine (clutch disengaged- the clutch pedal is being pressed down). When the engine is running and the clutch is engaged (i.e., clutch pedal up), the flywheel spins the clutch plate and hence the transmission.

The pattern of nigh manual transmissions for cars is that gear ratios are selected by locking selected gear pairs to the output shaft inside the manual. This is a fundamental divergence compared with a typical hydraulic automated manual, which uses an epicyclic (planetary) design, and a hydraulic torque converter. An automated transmission that allows the commuter to command the gear choice (such as shift paddles or "+/-" positions on the gear selector) is chosen a manumatic transmission, and is not considered a transmission transmission. Some automatic transmissions are based on the mechanical build and internal design of a manual transmission just accept added components (such as computer-controlled actuators and sensors) which automatically control the timing and speed of the gear shifts and clutch; this design is typically called an automatic transmission manual (or sometimes a clutchless manual transmission).

Contemporary manual transmissions for cars typically use five or six frontwards gears ratios and one opposite gear, however, transmissions with between ii and vii gears have been produced at times. Transmissions for trucks and other heavy equipment oft have betwixt eight and twenty-five gears,^{[ citation needed ]} in gild to proceed the engine speed within the optimal power band for all typical road speeds. Operating such transmissions often uses the same pattern of shifter movement with a unmarried or multiple switches to appoint the next sequence of gears.

• Manual transmissions in functioning

• 

  Performance of a constant-mesh 4-speed manual transmission.

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  Non-synchronous "crash" gearbox; with sliding-mesh blueprint. Used in older vehicles.

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  Operation of a constant-mesh 4-speed sequential transmission transmission; commonly used in motorcycles and race cars.

• 1936 film of automobile gearbox

History [edit]

1890s to 1940s [edit]

Many of the beginning automobiles were rear-engined, with a simple belt-drive functioning as a single-speed transmission. The 1891 Panhard et Levassor is considered a pregnant advance in automotive transmissions since it used a three-speed manual transmission.^{[2] [3]} This transmission, along with many like designs that it inspired, was a not-synchronous (also called sliding-mesh) design where gear changes involved sliding the gears along their shafts so that the desired cogs became meshed. The driver was therefore required to utilize careful timing and throttle manipulation when shifting, and so the gears would be spinning at roughly the aforementioned speed when engaged; otherwise, the teeth would refuse to mesh. This was hard to achieve, so gear changes were oft accompanied by grinding or crunching sounds, resulting in the gearboxes existence nicknamed "crash boxes".^[four] Fifty-fifty after rider cars had switched to synchronous transmissions (i.e. with synchronizers), many transmissions for heavy trucks, motorcycles and racing cars remained non-synchronous, in guild to withstand the forces required or provide a faster shift fourth dimension.

1950s to 1980s [edit]

The first car to utilise a transmission transmission with synchromesh was the 1929 Cadillac,^[5] nevertheless most cars continued to use non-synchronous transmissions until at to the lowest degree the 1950s. In 1947, Porsche patented the dissever ring synchromesh arrangement, which went on the become the near common design for passenger cars.^[6] The 1952 Porsche 356 was the first car to apply a transmission with synchromesh on all forward gears.^{[7] [8]} In the early on 1950s, most cars only had synchromesh for the shift from third gear to second gear (drivers' manuals in vehicles suggested that if the driver needed to shift from second to first, it was best to come to a consummate stop beforehand).

Up until the tardily 1970s, most transmissions had iii or four forward gear ratios, although 5-speed transmission transmissions were occasionally used in sports cars such as the 1948 Ferrari 166 Inter and the 1953 Alfa Romeo 1900 Super Dart. Five-speed transmissions became widespread during the 1980s, as did the utilize of synchromesh on all forrad gears.

1990s to present [edit]

Half-dozen-speed manual transmissions started to emerge in loftier-performance vehicles in the early 1990s, such every bit the 1990 BMW 850i and the 1992 Ferrari 456. The first vi-speed transmission transmission was introduced in the 1967 Alfa Romeo 33 Stradale. The first 7-speed manual transmission was introduced in the 2012 Porsche 911 (991).^[ix]

In 2008, 75.two% of vehicles produced in Western Europe were equipped with manual manual, versus xvi.1% with automated and viii.7% with other.^[10]

Internals [edit]

Shafts [edit]

A manual transmission has several shafts with various gears and other components attached to them. Virtually modernistic passenger cars use 'constant-mesh' transmissions consisting of 3 shafts: an input shaft, a countershaft (likewise chosen a layshaft) and an output shaft.^[11]

The input shaft is connected to the engine and spins at engine speed whenever the clutch is engaged.^[12] The countershaft has gears of diverse sizes, which are permanently meshed with the corresponding gear on the input shaft.^[thirteen] The gears on the output shaft are besides permanently meshed with a corresponding gear on the countershaft, nonetheless, the output shaft gears are able to rotate independently of the output shaft itself (through the use of bearings located between the gears and the shaft).^[14] Through the utilise of collars (operated using the shift rods), the speed of the output shaft becomes temporarily locked to the speed of the selected gear.^[15] Some transmission designs—such equally in the Volvo 850 and S70—have two countershafts, both driving an output pinion meshing with the front-cycle-drive transaxle's ring gear. This allows for a narrower transmission since the length of each countershaft is halved compared with one that contains 4 gears and two shifters.

The fixed and free gears tin be mounted on either the input or output shaft or both. For example, a five-speed transmission might have the first-to-2d selectors on the countershaft, but the third-to-fourth selector and the fifth selector on the main shaft. This means that when the vehicle is stopped and idling in neutral with the clutch engaged and the input shaft spinning, the tertiary-, quaternary-, and 5th-gear pairs do not rotate.

When neutral is selected, none of the gears on the output shaft are locked to the shaft, allowing the input and output shafts to rotate independently. For reverse gear, an idler gear is used to reverse the direction in which the output shaft rotates. In many transmissions, the input and output shafts can be directly locked together (bypassing the countershaft) to create a i:1 gear ratio which is referred to as direct-drive.

In a manual for longitudinal engined vehicles (eastward.m. most rear-wheel-drive cars), it is mutual for the input shaft and output shaft to be located on the same axis, since this reduces the torsional forces to which the transmission casing must withstand. The associates consisting of both the input and output shafts is referred to as the master shaft (although sometimes this term refers to only the input shaft or output shaft). Independent rotation of the input and output shafts is made possibly by one shaft being located inside the hollow bore of the other shaft, with a begetting located between the 2 shafts.

In a transmission for transverse engined vehicles (eastward.g., front-wheel-drive cars), there are unremarkably but two shafts: input and countershaft (sometimes chosen input and output). The input shaft runs the whole length of the gearbox, and there is no separate input pinion. These transmissions also have an integral differential unit, which is connected via a pinion gear at the end of the counter/output shaft.

• Gear choice in a constant-mesh transmission

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  First gear (blueish, to back)

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  Second gear (blue, to front)

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  Third gear (majestic, to back)

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  Quaternary gear (purple, to front)

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  Opposite (green engaged)

• 

  Neutral (all disengaged)

Canis familiaris clutch [edit]

In a modernistic 'constant-mesh' manual manual, the gear teeth are permanently in contact with each other, and dog clutches (sometimes called dog teeth) are used to select the gear ratio for the transmission. When the domestic dog clutches for all gears are disengaged (i.e. when the transmission is in neutral), all of the gears are able to spin freely around the output shaft. When the commuter selects a gear, the dog clutch for that gear is engaged (via the gear selector rods), locking the transmission's output shaft to a particular gear ready. This means the output shaft rotates at the same speed as the selected gear, thus determining the gear ratio of the transmission.^[16]

The dog clutch is a sliding selector mechanism that sits around the output shaft. It has teeth to fit into the splines on the shaft, forcing that shaft to rotate at the same speed as the gear hub. However, the clutch tin can move back and forth on the shaft, to either engage or undo the splines. This movement is controlled by a selector fork that is linked to the gear lever. The fork does not rotate, so information technology is attached to a neckband bearing on the selector. The selector is typically symmetric: it slides between ii gears and has a synchromesh and teeth on each side in guild to lock either gear to the shaft. Unlike some other types of clutches (such as the foot-operated clutch of a manual-transmission car), a dog clutch provides not-slip coupling and is not suited to intentional slipping.

Synchromesh [edit]

In order to provide shine gearshifts without requiring the driver to manually lucifer the engine revs for each gearshift, most mod passenger motorcar transmissions use 'synchromesh' (also called 'synchronizer rings') on the forward gears. These devices automatically match the speed of the input shaft with that of the gear beingness selected, thus removing the need for the commuter to use techniques such every bit double-clutching. The synchromesh manual was invented in 1919 by Earl Avery Thompson and first used on production cars by Cadillac in 1928.^[17]

The need for synchromesh in a constant-mesh transmission is that the dog clutches require the input shaft speed to match that of the gear being selected; otherwise, the dog teeth will fail to engage and a loud grinding sound will exist heard as they clatter together. Therefore, to speed up or slow down the input shaft every bit required, cone-shaped brass synchronizer rings are attached to each gear. When the driver moves the gearshift lever towards the adjacent gear, these synchronizer rings press on the cone-shaped sleeve on the dog collar then that the friction forces tin can reduce the difference in rotational speeds.^[18] One time these speeds are equalized, the dog clutch can engage, and thus the new gear is now in use. In a modern gearbox, the action of all of these components is then shine and fast information technology is hardly noticed. Many transmissions practise not include synchromesh on the contrary gear (see Reverse gear section beneath).

The synchromesh system must also prevent the collar from bridging the locking rings while the speeds are still existence synchronized. This is accomplished through 'blocker rings' (as well called 'baulk rings'). The synchro ring rotates slightly because of the frictional torque from the cone clutch. In this position, the canis familiaris clutch is prevented from engaging. One time the speeds are synchronized, friction on the blocker ring is relieved and the blocker ring twists slightly, bringing into alignment certain grooves or notches that allow the dog clutch to fall into the appointment.

Common metals for synchronizer rings are brass and steel, and are produced either by forging or sheet metal shaping. The latter involves stamping the piece out of a canvas metal strip and so machining to obtain the exact shape required. The rings are sometimes coated with anti-wear linings (as well chosen 'friction linings') made from molybdenum, iron, bronze or carbon (with the latter normally reserved for high-performance transmissions due to their high cost).^[19]

Mechanical clothing of the synchronizer rings and sleeves can crusade the synchromesh system to become ineffective over time. These rings and sleeves have to overcome the momentum of the entire input shaft and clutch disk during each gearshift (and as well the momentum and ability of the engine, if the commuter attempts a gearshift without fully disengaging the clutch). Larger differences in speed between the input shaft and the gear crave higher friction forces from the synchromesh components, potentially increasing their wear rate.

Reverse gear [edit]

Even in modern transmissions where all of the frontwards gears are in a constant-mesh configuration, frequently the contrary gear uses the older sliding-mesh ("crash box") configuration. This ways that moving the gearshift lever into reverse results in gears moving to mesh together. Another unique attribute of the opposite gear is that information technology consists of 2 gears—an idler gear on the countershaft and some other gear on the output shaft—and both of these are direct fixed to the shaft (i.due east. they are always rotating at the same speed equally the shaft). These gears are ordinarily spur gears with directly-cutting teeth which—unlike the helical teeth used for forward gear—results in a whining sound as the vehicle moves in opposite.

When reverse gear is selected, the idler gear is physically moved to mesh with the corresponding gears on the input and output shafts. To avert grinding as the gears brainstorm to the mesh, they need to be stationary. Since the input shaft is often still spinning due to momentum (even after the motorcar has stopped), a mechanism is needed to stop the input shaft, such every bit using the synchronizer rings for 5th gear. Yet, some vehicles do employ a synchromesh arrangement for the reverse gear, thus preventing possible crunching if reverse gear is selected while the input shaft is still spinning.^[20]

Nigh transmissions include a lockout mechanism to forbid contrary gear from beingness accidentally selected while the car is moving forwards. This can take the course of a neckband underneath the gear knob which needs to exist lifted or requiring extra forcefulness to push button the gearshift lever into the plane of reverse gear.

Non-synchronous transmission [edit]

Another pattern of transmission that is used in older cars, trucks, and tractors, is a non-synchronous transmission (also known as a crash gearbox). Non-synchronous transmissions use a sliding-mesh (or constant-mesh, in later years) blueprint and accept the nickname "crash" because the difficulty in irresolute gears can lead to gear shifts accompanied by crashing/crunching noises.

Clutch [edit]

Vehicles with manual transmissions utilize a clutch to manage the linkage between the engine and the transmission, and decouple the transmission from the engine during gearshifts and when the vehicle is stationary. Without a clutch, the engine would stall whatsoever time the vehicle stopped, and changing gears would be difficult (deselecting a gear while the transmission requires the driver to adjust the throttle then that the manual is non under load, and selecting a gear requires the engine RPM to be at the exact speed that matches the road speed for the gear beingness selected).

Well-nigh motor vehicles utilize a pedal to operate the clutch; except for motorcycles, which usually have a clutch lever on the left handlebar.

Gear stick [edit]

In nigh vehicles with a manual transmission, the commuter selects gears by manipulating a lever chosen a gear stick (likewise called a gearshift, gear lever or shifter). In most automobiles, the gear stick is located on the floor betwixt the commuter and forepart passenger, merely some cars have a gear stick that is mounted to the steering cavalcade or center console.

The movement of the gear stick is transferred (via solid linkages or cables) to the selector forks inside the transmission.

Motorcycles typically employ sequential manual transmissions, although the shift design is modified slightly for safety reasons. Gear selection is usually via the left-foot (or, on older motorcycles; correct-pes) shift lever with a layout of 1–Due north–2–3–4–5–half-dozen.

External overdrive [edit]

In the 1950s, 1960s, and 1970s, fuel-efficient highway cruising with low engine speed was in some cases enabled on vehicles equipped with iii- or 4-speed transmissions by means of a divide overdrive unit in or behind the rear housing of the manual. This was actuated either manually while in high gear by throwing a switch or pressing a button on the gearshift knob or on the steering column, or automatically by momentarily lifting the pes from the accelerator with the vehicle traveling above a certain route speed. Automatic overdrives were disengaged by flooring the accelerator, and a lockout control was provided to enable the driver to disable overdrive and operate the transmission as a normal (non-overdrive) manual.^[21]

The term 'overdrive' is as well used to describe a gear with a ratio of less than one (e.g., if the summit gear of the transmission has a ratio of 0.eight:1).

Push starting [edit]

Vehicles with a manual transmission tin can often be push started when the starter motor is not operational, such as when the car has a dead battery.

When push-starting, the energy generated by the wheels moving on the road is transferred to the driveshaft, and then the transmission, and eventually the crankshaft. When the crankshaft spins equally a result of the energy generated by the rolling of the vehicle, the motor is cranked over. This simulates what the starter is intended for and operates in a like way to creepo handles on very old cars from the early 20th century, with the cranking movement being replaced by the pushing of the machine.

Driving techniques [edit]

Vehicles with manual transmissions, and an experienced driver, tin can advance more efficiently than automated vehicles. This is because transmission transmissions allow the driver to choose specific rpm/power to the tires while pushing the clutch and modulating the power output during clutch release to account for weight transfer, tire wear, temperature, and route conditions.^[22] Automated transmissions do not permit to select rpm during shifting or modulating power release to the tires subsequently the gears have shifted. These abilities enable an experienced driver to fully utilise the bachelor grip, maximize acceleration, and reduce (or promote) wheel spinning.

Recently, many automatic transmissions have included more gear ratios than their manual counterparts.^{[23] [24]}

Driving a vehicle with a transmission transmission is more hard than an automatic transmission for several reasons. Firstly, the clutch pedal is an extra command mechanism to operate and in some cases, a "heavy clutch" requires significant forcefulness to exist operated (this can likewise forestall some people with injuries or impairments from driving manual transmission vehicles). The operation of the gearstick— another office that is non required on automatic transmission cars— means that the driver must take one manus off the steering wheel while irresolute gears. Another challenge is that shine driving requires co-ordinated timing of the clutch, accelerator, and gearshift inputs. Lastly, a auto with an automatic transmission evidently does not require the driver to make whatever decisions about which gear to use at any given time. On the other hand, beingness able to choose a specific gear and engine rpm setting manually gives the commuter total command of the torque applied by the tires, a disquisitional ability for racing, and of import for spirited driving.

In some countries, a driving license issued for vehicles with an automatic transmission is not valid for driving vehicles with a transmission transmission, simply a license for transmission transmissions covers both.^[25]

Colina starts [edit]

Starting from a stationary position is a challenge in a transmission transmission machine, due to the extra strength required to accelerate the vehicle upward the hill and the potential for the auto to scroll backward in the time it takes to move the commuter'southward foot from the brake pedal to the accelerator pedal (to increase the engine RPM before letting out the clutch). The traditional method of hill starts in a manual transmission car is to apply the parking brake (also chosen "handbrake", "emergency restriction", or "e-restriction") to agree the vehicle stationary. This means that the driver's right pes is not needed to operate the restriction pedal, freeing information technology upwardly to be used on the throttle pedal instead. One time the required engine RPM is obtained, the commuter tin can release the clutch, also releasing the parking restriction every bit the clutch engages.

A device called the loma-holder was introduced on the 1936 Studebaker. Many modern vehicles use an electronically actuated parking brake, which often includes a colina-holder characteristic whereby the parking brake is automatically released as the driven wheels kickoff to receive power from the engine.^[26]

Other driving techniques [edit]

• Rev-matching is an effective way to downshift gears in a machine. This is peculiarly useful on a track where optimum acceleration is needed. Rev-matching can too take some stress off the clutch, as information technology will exist doing less piece of work in matching the engine speed to the wheels.^[27]
• Double-clutching can be advantageous for smoothly upwards shifting in order to accelerate, and when done correctly information technology prevents wearable on the "synchros" which normally equalize transmission input and output speeds to allow downshifting.
• Heel-and-toe shifting is an advanced driving technique used more often than not in performance driving with a manual gearbox, although some drivers apply information technology on the route in everyday conditions in the interest of effectiveness. This technique allows the driver to increase the engine's rpm/power during the braking stage of a bend in preparation for the leave/dispatch stage.
• Rowing is the technique of downshifting more than one gear along with the heel-and-toe technique to provide engine braking and smoother deceleration/braking while in the intermediate gears. This provides for maximum braking when going from top gear to a much lower gear, and optimal engine RPM for exiting the corner.

Truck transmissions [edit]

Some trucks have transmissions that wait and behave like ordinary consumer vehicle transmissions—these transmissions are used on lighter trucks, typically have upwardly to 6 gears, and usually take synchromesh.

For trucks needing more gears, the standard "H" pattern tin can be complicated for some truck drivers, and then additional controls are used to select additional gears. The "H" pattern is retained, then an additional control selects amid alternatives. In older trucks, the command is often a split up lever mounted on the floor or more recently a pneumatic switch mounted on the "H" lever; in newer trucks, the control is ofttimes an electric switch mounted on the "H" lever. Multi-control transmissions are built in much higher power ratings merely rarely employ synchromesh.

There are several common alternatives for the shifting pattern. The standard types are:

• Range transmissions use an "H" design through a narrow range of gears, then a "range" command shifts the "H" pattern betwixt high and low ranges. For example, an 8-speed range transmission has an H shift blueprint with 4 gears. The first through fourth gears are accessed when a low range is selected. To access the fifth through eighth gears, the range selector is moved to high range, and the gear lever again shifted through the first through 4th gear positions. In loftier range, the first gear position becomes fifth, the second gear position becomes sixth, and and then on.
• Splitter transmissions use an "H" pattern with a wide range of gears, and the other selector splits each sequential gear position in two: First gear is in the showtime position/low split, second gear is in the first position/high split up, tertiary gear is in second position/depression split up, 4th gear is in second position/high split, and so on.
• Range-Splitter transmissions combine range-splitting and gear-splitting. This allows even more gear ratios. Both a range selector and a splitter selector are provided.

Although in that location are many gear positions, shifting through gears commonly follows a regular design. For example, a series of upward shifts might use "movement to splitter direct; move to splitter overdrive; motion the shift lever to No. 2 and move splitter to underdrive; motion splitter to straight; motion splitter to overdrive; movement the shifter to No. iii and motility splitter to underdrive"; and so on. In older trucks using floor-mounted levers, a bigger trouble is mutual gear shifts require the drivers to motility their easily between shift levers in a single shift, and without synchromesh, shifts must exist carefully timed or the manual volition not engage. For this reason, some splitter transmissions have an additional "nether under" range, so when the splitter is already in "under" it tin can be apace downshifted over again, without the filibuster of a double shift.

Modern truck transmissions are most commonly "range-splitter". The about mutual 13-speed has a standard H pattern, and the pattern from the left upper corner is as follows: R, down to L, over and upwards to i, downwardly to 2, upwardly and over to 3, downwardly to 4. The "butterfly" range lever in the center front of the knob is flipped up to high range while in quaternary, and so shifted dorsum to 1. The i through 4 positions of the knob is repeated. Also, each tin can exist split using the thumb-actuated under-overdrive lever on the left side of the knob while in high range. The "thumb" lever is not available in depression range, except in 18 speeds; 1 through iv in the low range can be separate using the pollex lever and L can exist dissever with the "Butterfly" lever. Fifty cannot be carve up using the thumb lever in either the 13- or 18-speed. The 9-speed transmission is like a 13-speed without the under-overdrive pollex lever.

Truck transmissions use many physical layouts. For example, the output of an N-speed transmission may drive an M-speed secondary manual, giving a total of N*M gear combinations. Transmissions may be in split cases with a shaft in between; in separate cases bolted together; or all in one instance, using the same lubricating oil. The 2d manual is oft called a "Credibility" or "Brownie box" after a popular brand. With a third manual, gears are multiplied nonetheless again, giving greater range or closer spacing. Some trucks thus have dozens of gear positions, although almost are duplicates. Sometimes a secondary transmission is integrated with the differential in the rear axle, called a "two-speed rear end". Two-speed differentials are e'er splitters. In newer transmissions, in that location may be two counter shafts, so each main shaft gear can be driven from one or the other countershaft; this allows construction with brusk and robust countershafts, while all the same allowing many gear combinations within a unmarried gear case.

Heavy-duty transmissions are generally non-synchromesh. Sometimes synchromesh adds weight that could be payload, and is 1 more than thing to fail, and drivers spend thousands of hours driving so tin can take the time to learn to drive efficiently with a non-synchromesh transmission. Bladder shifting (besides called "floating gears") is irresolute gears without disengaging the clutch, usually on a non-synchronized transmission used past large trucks. Since the clutch is not used, information technology is piece of cake to mismatch speeds of gears, and the driver tin can quickly crusade major (and expensive) damage to the gears and the transmission.

Heavy trucks are usually powered with diesel fuel engines. Diesel fuel truck engines from the 1970s and earlier tend to have a narrow power ring, so they need many close-spaced gears. Starting with the 1968 Maxidyne, diesel truck engines take increasingly used turbochargers and electronic controls that widen the ability ring, allowing fewer and fewer gear ratios. As of 2021, armada operators oft utilize 9, 10, 13, or xviii-speed transmissions, but automatic manual transmissions are condign more common on heavy vehicles, as they can improve efficiency and drivability, reduce the barrier to entry for new drivers, and may improve prophylactic past allowing the driver to concentrate on road conditions.^{[ citation needed ]}

Lubrication [edit]

Transmission transmissions are lubricated with gear oil (or engine oil in some vehicles) which must be inverse periodically in some vehicles, although not as frequently as the fluid in an automatic manual. Gear oil has a characteristic odour considering it contains added sulfur-bearing anti-habiliment 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 direct-cut spur gears). 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.

See also [edit]

References [edit]

External links [edit]

• As Stick Shifts Fade Into Obscurity, Collectors See Opportunity 24 June 2021 New York Times commodity by Rob Sass