This function provides proportional RPMs between the left and right wheels. If the inside tire rotates 15 RPM less in a turn than going straight, then, the outside tire will rotate 15 RPM more than going straight. For example, when your vehicle goes around a corner, the wheel on the outside must travel faster than the wheel on the inside.
The differential distributes equal amounts of torque to both wheels. This permits the wheels to react to resistance, or provide traction, to give the wheel more resistance to rotate less. The wheel with less resistance rotates faster. Some vehicles, such as go-karts, are not equipped with a differential. In this case, both driving wheels are forced to rotate at the same speed, usually on a common axle driven by a simple chain-drive apparatus. Front wheel drive vehicles are designed differently in that the axle and differential assembly is located in the transmission axle assembly or transaxle.
Open Differential is the oldest and most common design that is suitable for various makes and models of vehicles. The powered pinion gear, located at the end of the driveshaft, engages with the ring gear, which then transmits power to both axles through another set of gears. The only flaw in its design is that when one wheel begins to slip, all power is in essence sent to the wheel with the least traction, making this setup unfit for rock climbing or high-speed racing.
Limited-Slip is similar to an Open Differential but utilizes an integrated clutch system. The clutch mechanism locks the left and right sides of the axle together when a wheel loses traction. This is the preferred system for high-performance vehicles such as drag racers and those towing heavy loads.
Torque-Vectoring is the latest and greatest in differential technology. Torque vectoring encompasses a complicated collection of sensors and electronics to obtain data from the steering system, throttle position, road surface, and more, giving it the ability to distribute power to each wheel, according to the data. This option provides maximum traction while cornering, increasing performance significantly.
Regular maintenance on any vehicle is a necessity from oil changes, belts, hoses, and other fluids. So in low grip situations, one of the wheels will eventually spin meaninglessly. Under hard acceleration, some FWD performance cars with an open differential will experience torque steer. Any basic vehicle will have a setup like this.
The BMW 3 Series is a good example. Locked differential: A locking differential is essentially the same as an open differential, but it can lock the wheels in place. Effectively, this creates a fixed axle, with both wheels rotating at the same speed. For the most part, this applies to off-roaders. As you can imagine, having one wheel spinning freely is of no use when trying to get up a rocky incline.
With both wheels rotating at the same speed, an SUV or even trucks , for that matter has more traction. In hardcore off-roaders, you also get front differential lockers for the ultimate in off-road grip. A Jeep Wrangler Rubicon is equipped with lockers both front and rear. Welded differential: This is a permanently locked differential, creating a fixed rear axle. It has a very specific application, which is going sideways.
Welded differentials are pretty much standard at drifting events. If you like going sideways, you might be tempted to do the same, but we do not recommend it.
A welded diff generates a lot of heat, and at some point, it will explode, most likely taking a few other vital components with it. It's also extremely cumbersome at low speeds since it causes tires to scrape when turning.
Limited-slip differential: A limited-slip differential LSD offers the best of both worlds but usually is only found in rear-wheel drive RWD performance cars. An LSD will allow the two wheels to spin independently but limit the speed at which they can spin independently. This improves traction, which is why it's usually found on high-performance sports car models or serious four-wheel-drive 4WD machines. The mechanical clutch LSD comes with pressure rings that apply force on clutch plates alongside the gears.
This then locks the differential. The clutches can also be electronically controlled, which is how most all-wheel-drive cars function. Most all-wheel-drive AWD vehicles are front-wheel drive, but a center differential can be electronically activated to engage the rear wheels. A viscous LSD uses a much simpler setup.
A thick viscous fluid is used instead of the clutch plates mentioned above. When this liquid is subject to force, it becomes more rigid, forcing the differential to lock. It can eventually lose its viscosity, leading to problems.
Regular servicing should keep it in good shape, however. Torsen differential: A Torsen differential is once again the same setup as an open differential, but with additional "worm gears" surrounding the bevel gears. A Torsen differential is open most of the time and transfers torque equally between the front and rear axle. When a wheel on a particular axle starts rotating faster than the opposite wheel, the pinion gears and worm gears bind together in a way that sends power to the slower spinning wheel.
The Torsen differential allows multiple worm gear designs, which means manufacturers can tune them to their specifications. Active differentials: This differential is similar to a limited-slip differential, but instead of using mechanical components to control the clutches, they're electronically controlled.
There are multiple benefits to this system, though it is costly. When equipped with various sensors, the vehicle's ECU can make millions of calculations per second about what wheel requires power.
Torque vectoring: This is a step up from the traditional limited-slip diff. Instead of using clutches to lock the differential when the speed difference is too big, a torque vectoring system can reduce power on one side and increase torque.
This allows for a sharper turn-in, which is why you'll usually find it in high-end performance cars. Torque vectoring, like rear-wheel-steering, can help a bigger car feel much more agile. It then reduces engine power, or brakes the spinning wheel, or both, to get things under control. Sometimes you want a wheel to spin, such as when trying to get out of deep snow, so traction control can be temporarily disabled with a button on the dash.
Some vehicles, primarily performance models, use a limited-slip differential instead of an open one. If one wheel loses traction, power goes to the other wheel. This reduces wheel spin, and on a higher-powered FWD vehicle, helps prevent torque-steer — the tendency for a front-driver to pull from side to side when you step on the throttle. Limited-slips all serve the same purpose, but exactly how they do it depends on what type they are.
A mechanical-clutch differential has clutch plates alongside the gears, and when needed, pressure rings press on the plates to provide resistance. All differentials get you around a corner, but some do it better than others. A vehicle with torque vectoring sends a little more power to the outside wheel.
Some automakers provide an electronic torque-vectoring effect, using sensors to apply the brake on the inside wheel so the vehicle pivots around this slower-turning tire.
In a true torque-vectoring system, the differential sends more power to the outside wheel. A locking differential lets the wheels turn at different speeds most of the time, but when its locking function is activated, the wheels both turn at the same speed.
In addition to a rear-wheel locking differential, the toughest 4x4s will also have a locking front differential. That centre differential may also be open, limited-slip, viscous, or Torsen. If those wheels start to slip, the differential sends power to the other.
Some vehicles send power to both axles all the time, although one generally gets more than the other. True 4WD systems power the rear wheels, but have a transfer case that sends power to all four wheels when activated.
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