The spiders have no bearings or bushings…Just steel against steel in an oil bath
Thanks for the vdo link. From what I can see from that vdo, and taking into account the vdo model arrangement isn’t really how a differential is typically configured, the pinion shaft is fixed w/respect to the case; i.e. it doesn’t rotate (other than end over end) as the case rotates.
It seems like that pinion shaft takes on a whole lot of force. I wonder what they have to do to prevent it from bending/deforming?
All of the torque driving the wheels goes through the pinion shaft, but a 3/4" - 1" bar of steel is pretty strong. High powered vehicles have two pinion shafts at 90 degrees to each other and 4 spider gears to share the load.
That spider gear shaft doesn’t rotate either, it contains a bolt through it to hold it in the diff case.
As for Torsen diffs, they are wonderful. They spread traction to each wheel but don’t cause a rear drive car to break loose as easily as a clutch type limited slip diff. The clutch type requires torque across the axle to break it loose so the axles can turn different speeds in a corner. On snow, that isn’t gonna happen. That’s why new Mustangs and Camaros use Torsen diffs.
I couldn’t use a Torsen on my road race car 'cause occasionally the inside wheel was airborne…
@B.L.E.
The last two tractors I have (had), were never used in situations where I felt I had to used the braking separately. I have always had 4 wd where many farm tractors were two wheel drive and needed the extra control. Un driven front wheels tend to plow straight ahead and you need the turning power of the rear wheels. Also, when the front wheels are engaged with 4 wd, that differential locks and the rear locks with a foot lever. You can’t get any better drive then that. Most tractors have no brakes on the front wheels. The brakes are only on the back, often wet discs emerged in the rear differential. So, you need four wheel drive in hilly areas, just to brake the front wheels through the transmission. In the old days.many many people died in tractor accidents because of their design. Four wheel drive is almost a necessity to make a tractor safe with any hills what so ever. The front tires with that diff locked all the time, take a lot of wear. With less then 300 hours on my newest tractor, my fronts may need replacement in just another year.
If the planet gear shaft failed, it would likely fail by shearing. The gears are right next to the housing that holds the shaft. Also, the shaft can’t turn with the gears because the gear on the opposite side turns in the other direction.
The lug nut bolts on your wheels are subject to the same forces that the planet gear shafts are and they aren’t anywhere near as thick as the planet gear shafts are.
That differential in the video was a designed to demonstrate the principles of differential gears, not to serve as a working differential and was designed for the express purpose of making it easy to see what is going on.
@dagosa I totally agree with how dangerous farm tractors are, there is no vehicle that’s easier to overturn, except maybe an industrial forklift. There’s no way I would want to mow a steep hillside next to an interstate right of way with a 1938 John Deere row crop tractor.
There are also a surprisingly large number of accidents with zero turn radius mowers when mowing sideslopes.