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Neptune
Indeed, a nice video showing how a open differential works. But what it doesn’t show is the dark side of open differentials.
A "open differential" allows for unlimited rotational speed difference between the axel shafts while splitting engine torque equally between the two drive wheels during normal driving. It’s the most common type of differential used in vehicles. It allows one wheel to infinitely turn faster than the opposing wheel while making turns. This makes the vehicle turn better, improves handling, reduces tire ware and virtually eliminates drivetrain binding and torque wind-up.
But if one wheel loses traction, the open differential will allow almost all of the torque to flow to that very wheel, leaving the opposing wheel with traction, helpless.
A good example is if a wheel is slightly lifted off the ground (resulting in complete traction loss, this event can sometimes happen off road) Take a 4x4 vehicle which normally has two differentials, front & rear (if its 4x4 system can be engaged on pavement, it will have a third center differential) When crossing a ditch one wheel will be lifted off the ground the lifted wheel will receive almost all of the supplied torque. Thus leaving the grounded wheel with not enough power (torque) to propel the vehicle forward. Open differentials are not good for 4x4 vehicles used for off road, but are more than adequate for cars or other on road vehicles.
"Electronic traction control" is used to control the undesired behavior of open differentials. If one wheel loses traction, a apply and release ABS brake cycle is initiated on that wheel. Breaking the said wheel causes resistance, which in turn causes the open differential to send some of the torque back to the opposing wheel with traction to propel the vehicle. Under normal driving conditions it allows the open differential to function as normal.
"Mechanical limited-slip differentials" perform the same as electronic traction control, but instead of using the ABS brakes, it uses an internal device (usually a clutch inside the differential case) to send some of torque back to the wheel with traction. The axle shafts are never completely locked. Under normal driving conditions it acts like an open differential.
Electronic traction control and mechanical limited-slip differentials can only send partial power to the wheel with traction, not all of it. As a result, both traction systems may not be able in some situations to deliver enough torque to the wheel (with traction) to get the vehicle moving.
"Mechanical locking differentials" can lock-up 100% when one wheel loses traction. Like electronic traction control and limited-slip differentials, locking differentials can send torque to the wheel with traction. But unlike them, locking differentials can send all 100% of the supplied torque to the wheel with traction. It does so by completely locking the axle shafts together (usually via clutch or gears) Under normal driving conditions it acts like an open differential.
Most vehicles (including 4x4s) use open differentials with electronic traction control. Some vehicles are still offered with limited-slip axle differentials, but electronic traction control has largely replaced the limited-slip differential as it performs the same with less complexity. Locking axle differentials are rarely offered by manufacturers as standard equipment. Most do not offer them at all. Locking axle differentials are largely a aftermarket item.
A "open differential" allows for unlimited rotational speed difference between the axel shafts while splitting engine torque equally between the two drive wheels during normal driving. It’s the most common type of differential used in vehicles. It allows one wheel to infinitely turn faster than the opposing wheel while making turns. This makes the vehicle turn better, improves handling, reduces tire ware and virtually eliminates drivetrain binding and torque wind-up.
But if one wheel loses traction, the open differential will allow almost all of the torque to flow to that very wheel, leaving the opposing wheel with traction, helpless.
A good example is if a wheel is slightly lifted off the ground (resulting in complete traction loss, this event can sometimes happen off road) Take a 4x4 vehicle which normally has two differentials, front & rear (if its 4x4 system can be engaged on pavement, it will have a third center differential) When crossing a ditch one wheel will be lifted off the ground the lifted wheel will receive almost all of the supplied torque. Thus leaving the grounded wheel with not enough power (torque) to propel the vehicle forward. Open differentials are not good for 4x4 vehicles used for off road, but are more than adequate for cars or other on road vehicles.
"Electronic traction control" is used to control the undesired behavior of open differentials. If one wheel loses traction, a apply and release ABS brake cycle is initiated on that wheel. Breaking the said wheel causes resistance, which in turn causes the open differential to send some of the torque back to the opposing wheel with traction to propel the vehicle. Under normal driving conditions it allows the open differential to function as normal.
"Mechanical limited-slip differentials" perform the same as electronic traction control, but instead of using the ABS brakes, it uses an internal device (usually a clutch inside the differential case) to send some of torque back to the wheel with traction. The axle shafts are never completely locked. Under normal driving conditions it acts like an open differential.
Electronic traction control and mechanical limited-slip differentials can only send partial power to the wheel with traction, not all of it. As a result, both traction systems may not be able in some situations to deliver enough torque to the wheel (with traction) to get the vehicle moving.
"Mechanical locking differentials" can lock-up 100% when one wheel loses traction. Like electronic traction control and limited-slip differentials, locking differentials can send torque to the wheel with traction. But unlike them, locking differentials can send all 100% of the supplied torque to the wheel with traction. It does so by completely locking the axle shafts together (usually via clutch or gears) Under normal driving conditions it acts like an open differential.
Most vehicles (including 4x4s) use open differentials with electronic traction control. Some vehicles are still offered with limited-slip axle differentials, but electronic traction control has largely replaced the limited-slip differential as it performs the same with less complexity. Locking axle differentials are rarely offered by manufacturers as standard equipment. Most do not offer them at all. Locking axle differentials are largely a aftermarket item.