What is the relationship between lsd, 2wd, and 4wd auto?

[Bluedog]

I know there are a million threads of lsd vs e-locker, but I wasn’t able to find this specific answer. I just got my new truck (yay!) but I’m not sure where the lsd comes into play between 2wd and 4wd auto. Thanks!

 

[YawnY]

lsd is Limited Slip Differential. So when say your left wheel loses traction, after a certain rotation a clutch inside will automatically lock both wheels together. 4wd auto is when the vehicle electronically detects slip and engages the front wheels to put the vehicle into 4x4.

 

[silver billet]

I'd like to know as well, how close the 4x4 auto is to the Jeep's 4x4 auto? Does the Ram use the brakes to stop wheel spin in 4x4 auto, kind of like a poor mans "diff lock"?

 

[YawnY]

I'd like to know as well, how close the 4x4 auto is to the Jeep's 4x4 auto? Does the Ram use the brakes to stop wheel spin in 4x4 auto, kind of like a poor mans "diff lock"?

LSD is mainly used for rear driving axles, although some front differentials have a locker as well (not sure about the ram) using traction control to brake a wheel which has loss traction is not really a 'poor mans diff lock' but more like controlling the power output. If the wheel slips, it causes the spider gear to spin and apply's power to one wheel. When applying breaking force to faster spinning wheel it helps the spider gear to push more than spin.

Here's a simple explanation that might help clear it up.

 

[heydre]

Great vid Yawn...made me think of planetary gears...also makes your head spin.

 

[Bluedog]

Ok awesome. So LSD is side to side, but 4wd auto is back to front, yes?

So if I am in 4wd auto, driving most of the time in 2wd, and my back left wheel slips, will the truck then engage both LSD to counter the side to side discrepancy AND engage 4wd because it senses the back left wheel slipping?

lsd is Limited Slip Differential. So when say your left wheel loses traction, after a certain rotation a clutch inside will automatically lock both wheels together. 4wd auto is when the vehicle electronically detects slip and engages the front wheels to put the vehicle into 4x4.

 

[Gman]

Ok awesome. So LSD is side to side, but 4wd auto is back to front, yes?

So if I am in 4wd auto, driving most of the time in 2wd, and my back left wheel slips, will the truck then engage both LSD to counter the side to side discrepancy AND engage 4wd because it senses the back left wheel slipping?

LSD/Anti-Spin is side to side in the rear, 4WD Auto directs power to the front if slippage is detected in the rear.

No matter which transmission mode you are in, the Anti-Spin diff works at any speed to apply power to both rear wheels if there's slippage on one rear wheel.

The E-Locker locks both rear axles electronically, but there are some other details in the manual:

Operating in 4WD LOW the locker can be engaged up to 40 mph (64 km/h) and will remain engaged throughout the 4WD LOW speed range.

Operating the locker in 2WD, 4WD AUTO, and 4WD LOCK/HIGH the locker can be engaged up to 20 mph (32 km/h). While driving with the locker engaged, if speed exceeds 25 mph (40 km/h), the locker will automatically disengage, but will automatically reengage at 20 mph (32 km/h).