Yes, it is wikipedia, but it's a pretty accurate explanation. From what I'd read on the Scout forums, they offered the auto locking variety - if you shifted into 4H/4L, you were in 4WD, but the procedure was to (in 2WD) manually turn the hubs to the "LOCK" position, get back in, shift into 4WD, and those axles were locked in. I never used them this way, so I can't speak to the advantages of auto versus locked. I have a feeling that someone on here is much more knowledgeable than I am.
stopped using them on Jeeps when the YJ debuted. Most CJs (except for Quadratrac Models) had them. When you wanted to run in 4x4, you got out of the jeep, turned the hubs from free wheel to lock. This locked the outer axles to be able to make the axle "live" for the 4x4 to work. When the hub was set at free, the axle performed like a 2 wheel drive. The front axle shafts were not engaged, so no 4x4 would be available when you pulled on the stick in the cab. I personally wish they were still available as an option for all axles. Just my opinion. You were sure you were in 4x4 or not. Simple and tried and true design. No vacuum motors to worry about, and the axle wasn't "live" like the new setups, less wear and tear and rotating mass.
They were an aftermarket item in the late 60's. They became a factory option in the mid 70's.
The idea was to disconnect the wheels from the axle - that stopped the axles from turning, giving better mileage from less drag - and most important - it took the gyroscopic effect of the axles out. Otherwise you could feel the gyroscopic effect when you didn't have them, or they were locked. The Jeep would wander.
When you wanted 4 wheel drive you had to get out and lock them - that just made them ready - they didn't put you in 4x4, you still had to shift the transfer case into 4 wheel.
The automatic lockout hubs would lock when the axles turned - by a Sprague clutch inside. They were much weaker than manual hubs. If you wanted to back up with the automatics, you had to manually lock them.
Warn was the leader, but there were several other brands too. Selectomatic etc., names since long forgotten.
I have 2 used sets on Ebay for sale right now.
You can still get kits to put them on the front and rear of a TJ - to disconnect the axles when flat towing. I think they are about $700 for each axle.
It's no wonder the country is falling apart - stupidity abounds!
I've had two sets of Warn manual locking hubs. One set in a custom 1986 Ford Bronco, the other in a 2001 Ford F350. The Warn hubs were brass while the OEM hubs were plastic. As rrich said, you had to step out to lock them. I usually got a mile or two per gallon better fuel economy while unlocked. The down side was they always seemed to be unlocked when I needed them most. Case in point, on a cold winter day with dry roads, I had them unlocked on my Bronco for my daily 45 mile commute to work. A camaro tried to pass another vehicle on a curve. The camaro was in my lane headed directly for me. I figured, in the second of time I had to figure, I could either run him over (literally - my Bronco had 35" BFGs and a 4" Ranco suspension lift) or take the berm of the road. Well we had a foot or more of snow off the road. If I'd had my hubs locked I could have shifted into 4hi and perhaps avoid the line of trees that destroyed my ride.
I don't think they'll fit our TJ without new axles, tho.
I put the Warn hub kit on my TJ ten years ago. The kit included the hubs, wheel bearings, outer axles shafts with ujoints, new brake rotors and several other items. I also changed out the inner axles shafts to matching chromaloy...put in a Powertrax noslip, and 4:56 gears (rear too). Some say its a waste to put them on but my experience has been good. If I lock the hubs and drive in 2wd at highway speeds there is more vibration and noise than when they are unlocked and nothing turns in the front drivetrain. I repack the bearings every spring and the original bearings are still rolling. The brake rotors are modified yj rotors and the wheel span is 1/4 inch wider. Mile marker sells a kit now and Randys Ring and Pinion bought the rights to the Warn kit.
It would be better to describe them as unlocking hubs instead of locking hubs. All they do when unlocked is to disconnect the wheel and hub from the axle shaft. In other words, the factory hubs are always locked anyway. They were invented by Warn to reduce bearing wear and help improve gas mileage. Later bearing and front-end designs made that benefit largely disappear.
Today, their need is mostly for those who anticipate breakage in their front-end and want to be able to drive home on the breakage by simply unlocking the hub(s) on the side of the broken axle shaft, ring & pinion gears, etc. Or to disengage an automatic front locker so it doesn't affect the steering when you're in 4x4.
They are useful, I had Warn hubs on my '97 TJ and again on my '04 TJ but few actually need them. For a stock TJ they are of little to no benefit.
__________________ ...Gone wheeling, back Sunday night.
Actually they were invented way before Warn was around. The Dana/Spicer corp made them way back when and an original set of spicer lockouts are 3 times stronger than anything warn ever made. Having the lockout hub on the front is a way better design than the crap everyone is making today. It makes your bearings/ujoints/axleshafts etc last alot longer and will give you better fuel economy. Ballistic fab is making kits right now that take the later model trucks automatic junk off and go back to the lockout style. For a standard jeep though I agree with Jerry, its not really worth the money spent unless your doing an axle swap to some older axles...which will have them already
I owned a stock 1981 Jeep CJ-7 that had the old 258 cube inline 6 cyl and a 4 speed manual. This Jeep had a limited slip rear and manual locking hubs. I like the locking hubs and think they should be offered as an option on all 4x4 vehicles. Two definite advantages I saw were the ability to totally disconnect the front diff in case of breakage and increased fuel mileage. In several controlled experiments, I found that I was getting about 30% better highway gas mileage with the hubs unlocked...you results may vary.
Two disadvantages that I experienced were the inconvenience of having to get out and lock the hubs when I need four wheel drive and front slip yoke/spline wear. Apparently, with the hubs unlocked, the front driveshaft sits in one position and frequent driving on rough roads will cause the slip yoke/splines to wear so that the driveshaft will rattle when you hit a bump. This wasn't an extreme problem as the Jeep had almost 100,000 miles on it when I sold it and I had never replaced the driveshaft.
... Two definite advantages I saw were the ability to totally disconnect the front diff in case of breakage and increased fuel mileage. In several controlled experiments, I found that I was getting about 30% better highway gas mileage with the hubs unlocked...you results may vary.
While I'll agree with your first statement, I'll disagree with your 30% mpg improvement with manual hubs... you definitely won't see a mpg by unlocking the TJ's hubs. If it was truly that easy to achieve a 30% mpg improvement, you can bet the Feds & EPA would have already forced the industry to go to either automatic or manual hubs. Or at least the auto manufacturers would have so they could more easily achieve their ever-increasing federally mandated CAFE (mpg) requirements. Achieving a 30% mpg improvement that easily would be like finding the Holy Grail.
And as one who has installed manual Warn hubs onto two different Jeeps, I'm here to tell you there is zero mpg difference in mpg when my hubs are locked vs. unlocked. The only way I can tell if my hubs are locked or not is to get out and look at them.
__________________ ...Gone wheeling, back Sunday night.