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62-407: The system offers a choice of four rear- or four-wheel driving modes with both high and low ranges, selected using a lever mounted alongside the gear shift lever, both in motion or stopped (depending on the mode to be selected). The system differs significantly from 'traditional' 4WD systems in that it offers more driven-axle modes in both high and low ranges than most other part-time systems on

124-401: A propeller shaft or tailshaft ) which transmits the rotational force to a drive axle at the rear of the vehicle. The drive axle may be a live axle , but modern rear-wheel drive automobiles generally use a split axle with a differential. In this case, one half-axle or half-shaft connects the differential with the left rear wheel, a second half-shaft does the same with the right rear wheel; thus

186-762: A FR platform. They also maintain FR layout on the now unibody Grand Cherokee and Durango . Hyundai and Kia have also been working with new FR-based vehicles in the US, the Genesis Coupe and Sedan, the Equus and the new Kia Quoris . Ford, on the other hand, seems to be moving away from FR-based vehicles with the discontinuation of the Panther Platform in 2011 and the Australasia-only Falcon in 2016. Excluding trucks, vans, and SUVs,

248-429: A differential (kart racing). However, other go-karts have two rear drive wheels too. Some dump trucks and trailers may be configured with a lift axle (also known as an airlift axle or drop axle ), which may be mechanically raised or lowered. The axle is lowered to increase the weight capacity, or to distribute the weight of the cargo over more wheels, for example, to cross a weight-restricted bridge. When not needed,

310-518: A factory differential lock, activating this will disable the off-road traction control mode. For this reason, unless an additional selectable front locker is fitted, MATT is preferred due to its high performance and action on all four wheels. As MATT uses the ABS system to rapidly apply and reapply braking force, in extremely slippery surfaces or when the wrong mode is selected (e.g. high range when it should be low range, resulting in excessive wheel speed and slip)

372-506: A more complex system dubbed Super Select II (SS4-II). In most respects the two are the same, although the torque -split in SS4-II is 33/67 front/rear, meaning two thirds of the torque is channelled to the rear axle. In Super Select (SS4i) the torque-split is an equal 50/50. SS4-II also offers an option to lock the rear differential, offering greater traction to the rear axle. Mode Select Rear-wheel drive Rear-wheel drive ( RWD )

434-403: A one-piece rear beam axle. In other types of suspension systems, the axles serve only to transmit driving torque to the wheels: the position and angle of the wheel hubs is made independent from the axles by the function of the suspension system. This is typical of the independent suspensions found on most newer cars, and even SUVs, and on the front of many light trucks. An exception to this rule

496-413: A protruding hub to which the axle shaft flange is bolted. The semi-floating axle setup is commonly used on half-ton and lighter 4×4 trucks in the rear. This setup allows the axle shaft to be the means of propulsion, and also support the weight of the vehicle. The main difference between the full- and semi-floating axle setups is the number of bearings. The semi-floating axle features only one bearing, while

558-422: A rear wheel is spinning (and vice versa) however the gearing ratio is doubled, increasing torque by more than 2x and reducing speed in each of the gears by the same factor. 2H is intended for normal daily use around town for better fuel economy and where loss of traction is not a concern. Mitsubishi (like other manufacturers) does not recommend that 2WD be used when towing as it can cause excessive heat and wear on

620-498: A remote location, it is advisable to use at least 4H so that in the rare event of a solenoid failure on the track, all the core 4WD modes of 4H, 4HLc and 4LLc will still be selectable as high and low ranges and the centre differential are manually selected via linkage and not dependent on electronics (with the exception of the most modern rotary dial models). The system is used on Mitsubishi's Pajero iO mini SUV , while its larger Pajero , Challenger , Triton and Delica models use

682-400: A single unit called a transaxle . The drive axle is a split axle with a differential and universal joints between the two half axles. Each half axle connects to the wheel by use of a constant velocity (CV) joint which allows the wheel assembly to move freely vertically as well as to pivot when making turns. In rear-wheel drive cars and trucks, the engine turns a driveshaft (also called

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744-608: A sporty presence, as were Ford's full-size cars based on the Ford Panther platform (the Ford Crown Victoria , Mercury Grand Marquis , and Lincoln Town Car ) until they were discontinued in 2011 in favour of the Ford Taurus, which Ford discontinued production in 2019, being formally available with either a transverse front-wheel drive or all-wheel drive layout. In Australia, FR cars remained popular throughout this period, with

806-427: A turn at all. Several manufacturers offer computer-controlled airlifts so that the dead axles are automatically lowered when the main axle reaches its weight limit. The dead axles can still be lifted by the press of a button if needed, for better maneuverability. Lift axles were in use in the early 1940s. Initially, the axle was lifted by a mechanical device. Soon hydraulics replaced the mechanical lift system. One of

868-419: A wide variety of road conditions and speeds.(Note: The 4H mode can be used all the time without the common drivetrain 'binding' associated with other traditional 4WD modes). 4HLc is a part-time four-wheel drive mode that locks the center differential to provide extra traction for sandy, snowy or poorly surfaced roads in "high range" mode, while 4LLc, the "low range" mode, also offers a much lower gearing, providing

930-407: Is a form of engine and transmission layout used in motor vehicles, in which the engine drives the rear wheels only. Until the late 20th century, rear-wheel drive was the most common configuration for cars. Most rear-wheel drive vehicles feature a longitudinally-mounted engine at the front of the car. The most common layout for a rear-wheel drive car is with the engine and transmission at the front of

992-403: Is a group of two or more axles situated close together. Truck designs use such a configuration to provide a greater weight capacity than a single axle. Semi-trailers usually have a tandem axle at the rear. Axles are typically made from SAE grade 41xx steel or SAE grade 10xx steel. SAE grade 41xx steel is commonly known as " chrome-molybdenum steel " (or "chrome-moly") while SAE grade 10xx steel

1054-500: Is a single bearing at the end of the axle housing that carries the load from the axle and that the axle rotates through. To be "semi-floating" the axle shafts must be able to "float" in the housing, bearings and seals, and not subject to axial "thrust" and/or bearing preload. Needle bearings and separate lip seals are used in semi-floating axles with axle retained in the housing at their inner ends typically with circlips which are 3¾-round hardened washers that slide into grooves machined at

1116-441: Is attached to a separate shaft. Modern passenger cars have split-drive axles. In some designs, this allows independent suspension of the left and right wheels, and therefore a smoother ride. Even when the suspension is not independent, split axles permit the use of a differential, allowing the left and right drive wheels to be driven at different speeds as the automobile turns, improving traction and extending tire life. A tandem axle

1178-445: Is known as " carbon steel ". The primary differences between the two are that chrome-moly steel is significantly more resistant to bending or breaking, and is very difficult to weld with tools normally found outside a professional welding shop. An axle that is driven by the engine or prime mover is called a drive axle . Modern front-wheel drive cars typically combine the transmission (gearbox and differential) and front axle into

1240-435: Is not an option, only transmission neutral. Shift operation in early version is done through a gated lever. Beginning in 2H at the rear-most position, the operator can push one notch forward into 4H without any lockout. To select 4HLc, the operator then pushes the lever sideways and forward into 4HLc, also without lockout. In this position 4LLc is locked out. In order to shift into 4LLc, the operator pushes directly downward on

1302-451: Is often referred to as a transaxle since the transmission and axle are one unit. Many of the cars built in the 19th century were rear-wheel drive, often with the engine mounted at the rear of the car. The first rear-wheel drive car with the engine mounted at the front was an 1895 Panhard model, so this layout was known as the "Système Panhard" in the early years. The layout has the advantage of minimizing mechanical complexity, as it allows

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1364-407: Is sent to the front and rear axles with the centre differential locked, ensuring that a percentage of power is still sent to the forward axles even if a rear wheel is spinning (and vice versa). 4LLc : 4WD, low range, locked centre differential. Power is sent to the front and rear axles with the centre differential locked, ensuring that a percentage of power is still sent to the forward axles even if

1426-423: Is the independent (rear) swing axle suspension, wherein the half-axles are also load-bearing suspension arms. Independent drive-trains still need differentials (or diffs), but without fixed axle-housing tubes attached. The diff may be attached to the vehicle frame or body, and/or be integrated with the transmission (or gearbox) in a combined transaxle unit. The axle (half-)shafts then transmit driving torque to

1488-488: Is to be used for extreme off-roading <30km/h. This doubles torque sent to the wheels while halving the speed. This mode is to be used in deep mud, rock climbing, steep hills, deep ruts, heavy snow and recovery situations. Not to be used on tarmac and sealed surfaces. In early versions of Super Select such as found in the Generation 2 Pajero, transfer-case neutral can be selected. On later models (Generation 3 and up) this

1550-421: Is very rare and if encountered is an indication that another method of self-recovery should be looked at. The system has built-in fault detection and a type of failover to mechanical systems. In the event of a vacuum solenoid failure, the vehicle will remain in the axle configuration last selected (2WD or 4WD) and the centre diff light will flash continuously indicating a fault. For this reason, if travelling into

1612-613: The Holden Commodore and Ford Falcon having consistently strong sales until their discontinuation in the late 2010s. In Europe, front-wheel drive was popularized by small cars like the Mini , Renault 5 and Volkswagen Golf and adopted for all mainstream cars. Upscale marques like Mercedes-Benz , BMW , and Jaguar remained mostly independent of this trend and retained a lineup mostly or entirely made up of FR cars. Japanese mainstream marques such as Toyota were almost exclusively FR until

1674-411: The right hand side front axle is disconnected and connected via a dog clutch mechanism on the front differential. Vehicles with Super Select feature 'drive flanges' which are splined hubs without hub-freewheeling. This results in a much stronger hub/axle assembly and greater reliability however means that the left hand side axle is always driven. The small loss in fuel economy when in 2WD due to spinning

1736-408: The transmission to be placed in-line with the engine output shaft, spreading weight under the vehicle. In comparison, a vehicle with the engine over the driven wheels eliminates the need for the drive shaft (replacing this with the transaxle of lighter combined weight), but has the disadvantage of concentrating all the weight in one location. In order to reduce the relative weight of the drive shaft,

1798-722: The 2003 Cadillac CTS . As of 2012, all but the SRX and XTS are FR-based vehicles. Chevrolet reintroduced the FR-based Camaro in 2009, and the Caprice PPV in 2011. Pontiac also had a short run with the FR-based G8 and Pontiac Solstice . A Chevrolet replacement for the G8 called the Chevrolet SS was released in 2013 and uses the FR layout. Chrysler and Dodge reintroduced the 300 and Charger on

1860-505: The Mustang is the only FR vehicle remaining in their lineup. With the increasing popularity of electric vehicles , RWD layouts have become more common again, as the packaging advantages of FWD layouts do not apply to these vehicles, whereas the generally more powerful drivetrains benefit from the better traction during acceleration of the RWD layout. Modern electronic stability control largely negate

1922-400: The axle is lifted off the ground to save wear on the tires and axle, and to increase traction in the remaining wheels, and to decrease fuel consumption. Lifting an axle also alleviates lateral scrubbing of the additional axle in very tight turns, allowing the vehicle to turn more readily. In some situations, the removal of pressure from the additional axle is necessary for the vehicle to complete

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1984-422: The axle, and controls the angle of the axle and wheels assembly to the vehicle body. The solid axles (housings) in this system must also bear the weight of the vehicle plus any cargo. A non-driving axle, such as the front beam axle in heavy-duty trucks and some two-wheel drive light trucks and vans, will have no shaft, and serves only as a suspension and steering component. Conversely, many front-wheel drive cars have

2046-426: The bearings, housings, and only a short section of the shaft itself, that also carries all radial loads. The full-floating design is typically used in most ¾- and 1-ton light trucks, medium-duty trucks, and heavy-duty trucks. The overall assembly can carry more weight than a semi-floating or non-floating axle assembly because the hubs have two bearings riding on a fixed spindle. A full-floating axle can be identified by

2108-411: The car, mounted longitudinally. Other layouts of rear-wheel drive cars include front-mid engine, rear-mid engine, and rear-engine. Some manufacturers, such as Alfa Romeo, Lancia, Porsche (944, 924, 928) and Chevrolet (C5, C6, and C7 Corvettes), place the engine at the front of the car and the transmission at the rear of the car, in order to provide a more balanced weight distribution. This configuration

2170-481: The combination of dog clutches and vacuum actuation, internal friction/tension can cause slow engagement at the diff when shifting at a standstill (as must be done when entering or exiting low-range) while shifting-on-the-fly is usually instant. Mitsubishi officially recommends shifting to neutral before engaging the low range mode, however some owners recommend shifting into forward or reverse and idling 30cm or so in that direction to assist engagement. In 2H and 4H mode

2232-424: The differential. 4H is intended for use on gravel, wet roads, snowy or dusty conditions. In fact Mitsubishi recommends this mode for almost all situations due to the enhanced handling and safety and lower drivetrain strain when towing. Unlike many part-time 4WD systems, 4H can be used on tarmac and hard surfaces without the risk of damaging the transfer case through gearbox windup (excessive, uneven torque applied to

2294-456: The early manufacturers was Zetterbergs, located in Östervåla, Sweden. Their brand was Zeta-lyften. The liftable tandem drive axle was invented in 1957 by the Finnish truck manufacturer Vanajan Autotehdas , a company sharing history with Sisu Auto . A full-floating axle carries the vehicle's weight on the axle casing, not the half-shafts; they serve only to transmit torque from the differential to

2356-561: The front-engine, front-wheel drive (FF) layout – this trend would spawn the SUV-van conversion market. Throughout the 1980s and 1990s, most American companies set as a priority the eventual removal of rear-wheel drive from their mainstream and luxury lineup. Chrysler went 100% FF by 1990 and GM 's American production went entirely FF by 1997 except the Corvette , Firebird and Camaro . Ford's Mustang has stayed rear-wheel drive, as it must maintain

2418-504: The full-floating assembly has bearings on both the inside and outside of the wheel hub. The other difference is axle removal. To remove the semi-floating axle, the wheel must be removed first; if such an axle breaks, the wheel is most likely to come off the vehicle. The semi-floating design is found under most ½-ton and lighter trucks, as well as in SUVs and rear-wheel-drive passenger cars, usually being smaller or less expensive models. A benefit of

2480-461: The inner end of the shafts and retained in/by recesses in the differential carrier side gears which are themselves retained by the differential pinion gear (or "spider gear") shaft. A true semi-floating axle assembly places no side loads on the axle housing tubes or axle shafts. Axles that are pressed into ball or tapered roller bearings, which are in turn retained in the axle housings with flanges, bolts, and nuts do not "float" and place axial loads on

2542-580: The late 1970s and early 1980s. Toyota's first FF vehicle was the Toyota Tercel, with the Corolla and Celica later becoming FF while the Camry was designed as an FF from the beginning. The Supra, Cressida, Crown , and Century remained FR. Luxury division Lexus has a mostly FR lineup. Subaru's BRZ is an FR car. The fact that a driveshaft is needed to transfer power to the rear wheels means a large centre tunnel between

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2604-415: The left axle is considered negligible and outweighed by the strength and convenience advantages. Reduced frictional losses in the drivetrain mean that fuel economy improves while noise levels are reduced. It is a full-time four-wheel drive mode using a viscous coupling unit (VCU) and center differential to direct drive to the front wheels when the rear axle loses traction, and is capable of handling

2666-402: The lever to bypass the lockout and forward into the 4LLc position. To return, the operator simply pulls backward on the lever, no lockout needs to be bypassed. In newer versions of Super Select such as in Generation 4 Pajeros, there is a straight forward/backward travel with lockout on every position. The operator simply presses down and slides the lever forward into the desired position and does

2728-399: The market. The system features 4 modes: 2H, 4H, 4HLc and 4LLc. On early models, a neutral position for the transfer case was also selectable. 2H : 2WD, high range. 100% of available power is sent to the rear axle. 4H : 4WD, high range. Power is sent to both the front and rear axles while the centre differential remains unlocked. 4HLc : 4WD, high range, locked centre differential. Power

2790-552: The maximum amount of traction. Changing between 4HLc and 4LLc is only possible with the vehicle stationary (Note: 4HLc and 4LLc are your more traditional four-wheel drive modes, and should never be used on high traction road surfaces, as drivetrain 'binding' damage will occur). Engagement of 4HLc or 4LLc automatically switches Mitsubishi's traction control into off-road mode for vehicles equipped with MATT (Mitsubishi All-Terrain Technology). This mode disables stability control and modifies

2852-429: The overall weight-bearing capacity of a vehicle, and its potential for causing wear or damage to roadway surfaces. Axles are an integral component of most practical wheeled vehicles. In a solid, "live-axle" suspension system, the rotating inner axle cores (or half-shafts) serve to transmit driving torque to the wheels at each end, while the rigid outer tube maintains the position of the wheels at fixed angles relative to

2914-458: The potentially more difficult handling during challenging circumstances. Some examples of electric models utilizing a RWD layout are the single motor variants of the Tesla Model 3 , Volkswagen ID.4 and Kia EV6 . Axle An axle or axletree is a central shaft for a rotating wheel or gear . On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to

2976-508: The rear seats; therefore, cars such as the Mazda RX8 and the Porsche Panamera forgo a centre rear seat and divide both seats by a centre tunnel. In the 21st century, most cars are FF, including all front-engined economy cars, though FR cars are making a return as an alternative to large sport-utility vehicles. In North America, GM returned to the production of FR-based luxury vehicles with

3038-492: The same to return. In the most modern versions of Super Select such as in Pajero Sport and Tritons, selection is done via an electronic rotary dial. 4HLc and 4LLc are locked out and require a downward press to bypass. On all versions, 4WD engagement is done via solenoid-activated vacuum actuators and physical linkages on the transfer case. Though on rotary dial models these linkages are electronically shifted via servos. Due to

3100-399: The system's constant and rapid brake application on a constantly slipping wheel over an extended period of time (>1min continuously) can result in a short, temporarily low brake vacuum level. This is made known to the operator through a high pitched cabin alarm. In this situation the operator should stop the vehicle for 15~30 seconds to allow for brake vacuum to be recovered. This occurrence

3162-506: The torque and allows a lighter shaft construction. In an era when petrol was cheap and cars were heavy, the mechanical advantages of the front-engine, rear-wheel-drive (FR) drivetrain layout made up for any disadvantage in weight terms. It remained almost universal among car designs until the 1970s. After the Arab oil embargo of 1973 and the 1979 fuel crises , a majority of American FR vehicles (station wagons and luxury sedans) were phased out for

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3224-462: The transfer input/output shafts through the difference in rotation speeds of each wheel when on a high-grip surface that cannot relieve this through slippage on the terrain itself). 4H can be used in moderate off-road situations where extra traction is desired, however as the centre differential remains unlocked, a single slipping wheel will result in power being fed to that wheel, halting forward progress (unless other traction aids are used). Depending on

3286-408: The transmission was normally split into two parts: the gearbox and the final drive. The gearbox was normally produced with its highest gear being 1:1, which offers some mechanical advantages. The final drive, in the rear axle, would then reduce this to the most appropriate speed for the wheels. As power is the product of torque and angular velocity, spinning the shaft faster for any given power reduces

3348-458: The two half-axles and the differential constitute the rear axle. The front drive axle is providing the force to drive the truck. In fact, only one wheel of that axle is actually moving the truck and trailer down the road. Some simple vehicle designs, such as leisure go-karts, may have a single driven wheel where the drive axle is a split axle with only one of the two shafts driven by the engine, or else have both wheels connected to one shaft without

3410-434: The vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a spindle . On cars and trucks, several senses of

3472-432: The version of Super Select, the operator can shift between 2H and 4H at speeds of up to either 80km/h or 100km/h. 4HLc is intended for high speed operation (~50km/h) in more challenging terrain such as mud, fording water, rutted or off camber terrain and snow where low speed operation is not necessary or possible. This mode is not to be used on tarmac and sealed surfaces due to the centre differential being locked. 4LLc

3534-432: The way traction control is implemented. When a wheel loses traction, the operator must increase throttle input slightly, MATT will then bring the slipping wheel to a halt, sending power to the opposite wheel, periodically releasing the braking on the slipping wheel to check if traction has been regained. The system operates at a rapid speed and comes close to differential locker performance in most terrains. If fitted with

3596-400: The wheel positions steady under heavy stress, and can therefore support heavy loads. Straight axles are used on trains (that is, locomotives and railway wagons), for the rear axles of commercial trucks, and on heavy-duty off-road vehicles. The axle can optionally be protected and further reinforced by enclosing the length of the axle in a housing. In split-axle designs, the wheel on each side

3658-403: The wheels, usually via constant-velocity joints . Like a full floating axle system, the drive shafts in a front-wheel-drive independent suspension system do not support any vehicle weight. A straight axle is a single rigid shaft connecting a wheel on the left side of the vehicle to a wheel on the right side. The axis of rotation fixed by the axle is common to both wheels. Such a design can keep

3720-400: The wheels. They "float" inside an assembly that carries the vehicle's weight. Thus the only stress it must endure is torque (not lateral bending force). Full-floating axle shafts are retained by a flange bolted to the hub , while the hub and bearings are retained on the spindle by a large nut. In contrast, a semi-floating design carries the weight of the vehicle on the axle shaft itself; there

3782-459: The word axle occur in casual usage, referring to the shaft itself, its housing, or simply any transverse pair of wheels. Strictly speaking, a shaft that rotates with the wheel, being either bolted or splined in fixed relation to it, is called an axle or axle shaft . However, in looser usage, an entire assembly including the surrounding axle housing (typically a casting ) is also called an axle . An even broader (somewhat figurative) sense of

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3844-411: The word refers to every pair of parallel wheels on opposite sides of a vehicle, regardless of their mechanical connection to each other and to the vehicle frame or body. Thus, transverse pairs of wheels in an independent suspension may be called an axle in some contexts. This very loose definition of "axle" is often used in assessing toll roads or vehicle taxes , and is taken as a rough proxy for

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