I am trying to figure out how the auto locking hubs work on my 1995 Ranger XLT 4x4, V6 4.0. When I move the 4wd switch to 4WD the light on the dash lights up indicating I am in 4WD, however neither of the front wheels are locked in and pulling. I have read about a pulse vacuum system, but upon inspection my truck does not seem to operate that way. I can't find any vacuum hoses electric wires running to the front hubs. I am trying to understand what causes the front hubs to lock-in, seems like there must be an actuator or solenoid some where. Any help would be appreciated, just trying to find a starting point on this one. Thanks.

 

It is done by movement and torque

Inside each hub are pieces that slide to lock, then slide to unLock

When in 2WD a front wheel turns but axle doesn't so that motion will unLock the hub if it was locked, slides the cam out

When you engage 4WD the axles are now powered, so when you move the axles turn and pull cam in and Lock the hub, and it stays locked as long as axle has power.

When wheel starts to turn axle again(2WD) the drag causes the unlock.

The hubs to tend to stay locked even in 2WD, if one or both are not unlocked, back up 50ft or so and that will unlock them, it doesn't hurt them to stay locked, as long as you don't hear a clicking noise, if you do then do the back up thing


Most common problem with these is Grease, people pack in grease because there is a wheel bearing in there, but the 4x4 hub cover is NOT a grease cap.
So clean off as much of the grease as possible, then clean it ALL OFF, lol.
And give the parts a coating of motor oil or ATF, this allows the cams to move.

Insides seen here: https://www.ranger-forums.com/genera...1-models-3747/


But parts do break and there are no replacements so best bet is to get manual hubs.

This is a conversion article but worth a look just to see where all the parts go: Automatic To Manual Hub Conversion : The Ranger Station

 

Thank you for the explanation, I'll start with inspecting the inside of the hubs. My guess is they are packed with grease, since I know the previous owner worked on them in the past. Thanks again.

 

Update:
Today I pulled both hubs today. They were both caked with grease, one was really gummy and stuck. Cleaned both up and added a light coat of ATF, all parts seemed to be moving freely. Took it for a drive afterward and still can not get any pulling action from the front wheels in 4WD or 4WD Low. I also got under the truck and had someone move the 4WD switch between 4wd and 2wd drive several times. I found the motor assembly mounted on the transmission and can hear motor activate and what sounds like a metal latching sound inside. Not sure whats next on this one?

 

Check that when in 4WD the front drive line is turning, being powered by the transfer case, that will tell you if transfer case is indeed switching to 4WD
And the turning of drive line and front axles is what Locks the front hubs

If front axle is turning then hubs may be bad, but both hubs being bad is a long shot, but if you don't know history of the truck then they may both be bad.

In 2WD you should be able to turn the front drive line by hand(unless hubs are locked), in 4WD it should not turn, it is tied/connected to rear drive shaft

If you have both front wheels off the ground(tires and hub covers off) and in 2WD you should be able to turn front drive line and watch hubs lock and then turn rotor and watch them unlock.
It is an OPEN differential on the front so only 1 axle will turn at first, but once it locks it gets harder to turn so power goes to the other side and it will turn and lock