Bearing of the four wheels, it has no rubber sleeve wrapped grease, usually add smooth oil demand?

The car all can rotating parts can be smooth, or wear quickly. Have a plenty of smooth oil liquid, demand change regularly, have a plenty of smooth oil, not demand change. For axle shaft of ball cage, steering machine outside the tie rod ball head, is smooth and grease, package these grease rubber plug without damage and make the oil leak, lifelong not demand a change. If plastic casing damaged, oil and rubber sets of all want to change, not in oil will be left out, bad grease will eventually cause smooth shortage. Today we would say four wheels bearing, it has no rubber sleeve wrapped grease, usually add smooth oil demand? Buses trucks is added to all the moving parts in the ordinary maintenance smooth fat project, has the specially added mouth, with a grease gun can directly into it. Car is not need to do the maintenance, the wheel bearing is also using smooth grease is smooth, but it is fully sealed structure as a whole. The bearing is blocked, the smooth oil will not flow to outside and inside the outside goes into the dirt. Fat just smooth flow not to come out, it would not loss, the role of it is just a simple smooth, there is no failure doesn't work. So don't need add four wheels usually smooth oil, without exception, don't need maintenance for life. Is don't need to do maintenance, but also has bad. The performance of the wheel bearing is broken is there is sound, ordinary is buzzing noise. Is due to lost the ball inside the circle or have abnormal wear and tear, rotates around with friction and making noise. Bearing with sound, can't repair, can only change. Different models bearing is different also, have a plenty of a monolithic, together with the shaft head, abs sensor integration in, broken will change at the same time, the price is very high. There is an ordinary small bearings, change the widget can only when changing, the price is cheap, but change to match, partners than in integral. Wheel bearing is very long, the life of the ordinary car mostly used to tens of kilometers above, some car ran hundreds of thousands of kilometers, life is not bad, we met in bearing normally local is old car. Bearing does not need maintenance, so its life in addition to its own quality problems, also has a lot to do with vehicles using environment. Bad roads, road always match, so don't slow down rutted road speed, vehicle weight compare with large, often full load or overload and so on, will affect the bearing of life. Several road and to use this way, will not only affect the service life of bearing, the suspension, the service life of tires and other chassis parts have influence, so the reduction of the central must slow down, don't overload.