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AI - VIEW
  • 6/2/2025
Transcript
00:00A differential is a key component in today's vehicles that became a standard feature in automobiles by the late 19th century.
00:09It transfers engine power to the driving wheels while allowing them to rotate at different speeds during turns.
00:19In this video, we'll take a close look at the working principle of an open differential and the clever mechanism inside to see how it works.
00:30An open differential is the simplest and most common type found in vehicles.
00:35However, it comes with a significant limitation, something you may have encountered, especially if you live in colder climates.
00:42We'll dive into that a little later in this video.
00:48Before we dive into the inner workings of a differential, let us share something that has helped us understand complex systems like this.
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01:37A differential is typically located between the drive wheels of a vehicle, and vehicles can have one or multiple differentials depending on the drivetrain configuration.
01:51The vehicle in this video is 4WD, also known as 4x4, not to be confused with all-wheel drive vehicles.
01:59It has two axles.
02:01An axle is a central shaft that connects the wheels and supports the vehicle.
02:07There's one differential in the front axle, and a second differential in the rear axle.
02:15These differentials are linked by drive shafts to the vehicle's transmission using a transfer case.
02:23An intermediate gearbox used in 4WD vehicles that splits the engine's power between the front and the rear axles.
02:34For simplicity, we will only focus on the rear differential in this video.
02:38When a vehicle is driving in a straight line, power flows from the engine to the transmission,
02:47then through the transfer case, drive shafts, and finally to the differential,
02:52which splits the power equally between the two driving wheels, allowing them to rotate at the same speed.
03:01When the vehicle turns, the outer wheel needs to cover a larger distance than the inner wheel, in the same amount of time.
03:08So it must rotate faster than the inner wheel.
03:15Without a differential, both wheels would be locked together,
03:18forcing them to rotate at the exact same speed when the vehicle turns.
03:24This would cause wheel slippage, increase wear, and make the vehicle harder to handle.
03:31The differential solves this problem by allowing the wheels to rotate at different speeds.
03:36Let's now take a look at the key components of an open differential.
03:45This is the axle housing that holds the differential gears.
03:50Mounted on the housing is the cover that allows for access to the differential gear.
03:55A filler plug is typically located on the differential cover.
04:01This plug can be removed to allow for an addition of differential fluid.
04:06The oil level is usually at the brim of the plug.
04:10Now, let's take a look inside the axle housing.
04:13The drive shaft transmits power from the engine to the differential input shaft.
04:23Attached to the input shaft is the pinion gear, which engages with a larger gear called the ring gear.
04:28The ring gear is connected to the differential case, or carrier, which is the housing that holds the differential gears in place.
04:39The case rotates along with the ring gear.
04:43Inside the differential case are two freewheeling spider gears, which allow each wheel to rotate at different speeds.
04:50These spider gears mesh with two side gears, each of which drives the axle shafts connected to the wheels.
05:00Because the pinion is smaller in diameter than the ring gear, the input shafts rotates at a higher speed than the axle shafts and wheels.
05:09This proportion is known as the axle ratio, or diff ratio.
05:14For instance, an axle ratio of 3.31 to 1 indicates that the pinion gear must rotate 3.31 times in order to rotate the axle shaft once.
05:28So how do all these components work together?
05:32The pinion gear turns the ring gear, which drives the differential case.
05:37As the case rotates, it causes the spider gears to orbit due to their attachment to the case.
05:44When the vehicle is driving in a straight line, both wheels rotate at the same speed, and the resistance from both wheels is equal.
05:54In this situation, the freewheeling spider gears do not rotate on their own axis, but instead push both side gears together at the same speed, distributing power equally to each wheel.
06:06When the vehicle turns, the outer wheel needs to rotate faster than the inner wheel.
06:15The slower inner wheel provides more resistance than the faster outer wheel, which causes the spider gears to rotate on their own axis.
06:23This produces slower rotation in one side gear and faster rotation in the opposite side gear, resulting in the vehicle's wheels turning at different speeds.
06:33The main limitation of an open differential arises when one wheel loses traction on a slippery surface, such as ice.
06:44In this situation, almost all the power is directed to the wheel with low traction, while the wheel with grip receives little to no power, causing the wheel without traction to spin freely.
06:58The open differential always applies the same torque to both wheels, however, because the spinning wheel lacks grip and spins easily, very little torque is transferred to the wheel with traction.
07:11As a result, the side gear connected to the wheel on the drive surface remains stationary, while the opposite side gear spins freely.
07:23This makes open differentials unsuitable for off-road conditions without the assistance of a traction control system.
07:31There are other types of differentials available, which we'd like to explore in a future video.
07:37Let us know in the comments what you'd like to see next.
07:39Meanwhile, check out this playlist for more deconstructed content.
08:09We'll see you next time.