Are some front wheel bearings adjustable?

I have a 96 Grand Caravan ES.
I was checking for a possible front wheel bearing going bad and discovered that the driver's side bearing had play in it. I had been noticing a vibration when turning the steering wheel to the right similar to bad front end alignment. After purchasing a new wheel bearing assembly, I began the work of removing the old one. To my surprise the axle nut was only finger tight. With the rotor off and the cotter pin, nut adjustment cover, nut and washer off, the hub slid right out of the the bearing assembly. My vehicle does not have sealed ball bearings. At least from my experience with sealed ball bearings, these are not the same. The outer bearing race and balls looked great so I repacked with grease and put it back on. After replacing the rotor, etc. and tightening the axle nut, there was no play in the bearing and a test drive showed no sign of any problem. What's up? The repair manual says I don't have adjustable wheel bearings.

Then they aren't adjustable, the axle nut being loose caused the bearing to come apart. It is a hub style bearing which means it is supposed to be a sealed unit and not serviceable. If it has come apart then it is only a matter of time before dirt and debris works its way in there and causes it to go bad. If you aren't having any trouble with it now then you should count yourself lucky but be prepared to replace it in the future.

Does that mean that these flange type bearings are just pressed together and the axle flange and nut keep them from coming apart? I've replaced front wheel bearings before and this is the first time that one came apart.

Yea, if you can ever get the thing as a complete assembly do it. Otherwise, you would have nearly as much fun jumping off of a cliff. You have to pull the bearing out of the hub and then press the flange off and hope the inner race near the flange doesn't come off with the flange.

I replaced both front wheel bearings in my 1998 Town & Country two years ago. The replacement bearings are a sealed unit that includes a new hub and mounting plate. They cost me $140 a piece. To replace, remove the hub nut, caliper and rotor, unbolt the hub & bearing assembly from the steering knuckle, bolt the new assembly on and put it all back together again.
Good Luck!

Since I tightened the axle nut, the bearing has been ok. I did keep the new one so that if and when it starts getting noisy, I can change it. So far so good.
Thanks for the comments.