For Janicholson or anyone else.

I was reading your reply about the H shimmy below and it got me thinking. I am going to show my ignorance here but if I don?t ask I will never know. I have never understood just exactly what pre load is on bearing adjustment. I have read on here in the past where someone may say this kind of bearing requires pre load and others types that do not. I have to admit that I am somewhat in the dark on the term of pre load. I have done my share of wheel bearings in my day like my ole dad showed me where I would snug them down to where the wheel would roll with resistance then back it off till it rolled free without any play in it. I read your post all the time and see that you have obtained a lot of wisdom so I would appreciate your explanation. Thank you sir.
Paul

its basically just to give it a little more past zero end play. like in a wheel brg. you dont want any side clearance as what i usually see people do. you tighten a hair more than zero end play. but you dont want to overdue it has the brg will get hot. and you dont want too loose as the brg. will be running around. so the rollers are set in the race and turn nice and freely in their spot. maybe kind of a bad explanation but thats what preload is. and it all depends on brg. size for the amount of preload.

and a new brg. requires more preload than a used one.

Your Dad showed you how to preload, just did not tell you what to call it. Some applications require a torque, be it inch or foot pounds, with some a surprising amount of foot pound torque, but almost all require some backing off. Prof. Nicholson can certainly give a better, and further explanation. Your lack of knowledge of a term is not ignorance.

There are several types of bearings that require preload. The most common types are angular contact ball bearings, and tapered roller bearings. (preloading a radial load ball bearing is a no no, as is for bushings and orher plain bearings.)
Preload is used to keep the bearing components in contact with each other with a modest pressure. This prevents the rollers or balls from being misaligned with the common centerline/axis of the inner and outer races through slop.
The misalignment will cause the contact lines on a roller, or the contact patches on a ball, to be misplaced allowing only one or two of them to be in partial or full contact. This dramatically increases the load on those rollers/balls remaining in contact. It further more allows the shafts or hub/shaft system to hammer within the slop.
Angular contact ball bearings require the least preload, amounting to a whisker (tech term) more pressure than touching. Tapered roller bearings often require much more.
Preload can be set by adjusting a nut to a point where the rolling (lubricated) resistance can be measured (often with a spring scale at a given distance from the shaft, tangent to the hub. The nut is then kept in position with a cotter pin or clamping system/locknut. Another way is to use shims between the bearing and its housing to put pressure between the two opposed bearing sets. (tapered roller bearings are almost always in opposed pairs) Another preload method is a cruch sleeve placed between the cones (inner race) on the shaft. this, one time use, sleeve is tightened (and crushed in length) using a specific torque on the shaft nut, or tightened until the rotation force of the hub is at spec. Another method is to use threaded collars that push on the outer races toward one another. This method also allows the location of a gear or flange on the shaft to be positioned as well. Commonly found in differentials for ring gear backlash setting and preload at the same time. Thanks for the confidence. Jim

On the other hand, the rest of the world pre-loads pinion bearings and differential side bearings, and sets wheel bearings and typical transmission countershaft bearings to somewhere in the .001" to .005" range of FREE PLAY.

DUNNO why some of you guys think wheel bearings need pre-load???

Don't think the official IH manual is gonna tell you to do that.

sorry i was not referring to ih wheel brgs. i was saying what reload on a brg. is. and with vehicles with disc brakes you dont want side clearance,but a bit of preload. it was a general answer. and yes i have set preload on pinion brgs and diff. side brgs.and on top drive units with the use of removing shims to get the proper preload of .007- ,010.of crush on the brg. with the use of a dial indicator. and i did not say tractors must have preload on the front wheels, but it dont hurt a thing as tapered rollers should have preload. as a brg wears the preload is gone. using the front wheels on an old tractor is a poor example to use as there is nothing critical involved.

I do know that some tapered roller bearings require only a finger tight preload. It depends on the application. I once torqued a front wheel bearing on a Nissan 310 to spec not knowing that the spacer in between the bearings had been removed by a previous miss-chanic. The spacer normally provides the preload. My mom said the wheel was roaring on the road. I checked it and the bearings were spalled.

I think old dad taught you right, preloading tapered brgs. is used in things like automotive differentials and if you load them too much you're going to have problems.