Ummm.. open differentials provide equal torque when there is equal traction and the vehicle is moving straight. Whenever traction is unequal, the differential provides all the torque to the wheel with the least traction and no torque to the wheel with traction, which is why they are worthless for off road use.
SoCalDesertRider wrote: Ummm.. open differentials provide equal torque when there is equal traction and the vehicle is moving straight. Whenever traction is unequal, the differential provides all the torque to the wheel with the least traction and no torque to the wheel with traction, which is why they are worthless for off road use.
Common misunderstanding, and you aren't the first to point it out.
Actually you are wrong though. The design of the spider gears guarantees equal TORQUE to each side, not RPM. In the case of your example, one tire spins because it lost traction and therefore can't put torque to the ground. No traction, no torque. The other tire appears to do nothing when in fact it's putting the exact same torque to the ground (none, or very little) If the spinning tire can grab even a little traction and deliver a tiny amount of torque, the other side will match it. This has nothing to do with RPM, in which case one tire can spin like crazy and the other does nothing. With an Open differential, torque is always equal (mechanically speaking) while RPM can vary.
Ever do a really smoky one wheel burnout (like when we were kids)? If you really got the spinning tire hot and melted the car would almost stop moving forward altogether. That was because the tire lost so much grip on the road that the torque applied dropped to near zero and the non-spinning tire always matches torque. When the spinning tire starts to grip and slow down the applied torque starts to increase, and the non-spinning tire matches pushing you forward with even thrust from both sides, even though one tire is smoking and the other is not.
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