Warning: long technical discussion to follow

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We need to be very careful when we talk about preloading a set of tapered bearings.
In general, tapered roller bearings need some end play (clearance). That is the case on automotive wheel applications. It is also true of most, but not all, machine applications.
There are many applications that use a crush sleeve to maintain a very tight tolerance spacing between tapered bearings in order to accurately control end play. Some use a sleeve and shims. In most of these applications, you use a dial indicator to set up the bearing assembly (to check amount of end play). When you work on those types of applications, you do apply quite a bit of torque to a locking nut. That is not to be confused with applying "clamping forces" to two tapered bearings that do not have controlled spacing.
In addition to designing tapered roller bearings to handle thrust loads (such as on the side load of wheels in corners), tapered bearings are used to very accurately locate mechanical components such as gears. In this case, there is some very carefully controlled preload on the bearing. The bearing capacity is designed to take into account the thrust load of the gear and the affect of the preload. Generally, these applications are submerged in oil so that heat is carried away from the bearing. An example of this are the pinion bearings in a rear end. When you read the manual, you will see that it is quite an exacting process to get a very accurate preload on the bearings.
Getting back to the basics of tapered bearings, the problem is that these bearings are indeed tapered. A taper is the same as a wedge. We all know that a little force on the end of a wedge causes a BIG force on the separating surface of the wedge. In the case of these bearings, that huge force is exerted on the inner race/rollers/outer race.
Tapered bearings are designed to take very large side loads in a wheel/axle type application. If we tighten the bearing (preload), we use most or all of the thrust capacity of the bearing.
If you poke around the internet, you will not find much general information on tapered bearing maintenance. This is partly a result of the fact that they are rather application specific. One process does not fit all applications. The following gives some general information:
http://motionsystemdesign.com/mag/adjusting_tapered_bearings/