It’s doing my head in because yesterday I was certain it worked that way. But was informed that I was wrong so I tried all my stock of books and none give the answer in simple terms. One infers it and gives a picture with arrows but depends how you read the diagram.
Guys - I believe it is small end of taper to larger end - some v.large assemblies with Timken's had positive oil feeds to overcome this when a natural (gravity) oil feed wasn't avaialable (spindle oriented into a position where oil did not naturally feed).
Most critical applications now use grease for life method - with Kluber - this has to be run in & is very expensive - but it does work - rotations in excess of 4000/min.
If you need to preload the bearings, grease (including Kluber) does not work very well. (This is based on personal bitter experience, and I think knowledgeable people at Timken will confirm it, assuming you can get hold of them). You need really good lubrication between the rib and the ends of the rollers, which among rolling element bearings is a feature almost unique to taper rollers. Unlike the rolling contacts on the outside of the rollers, which experience elasto-hydrodynamic lubrication, the rib lubrication regime is almost purely hydrodynamic, which requires much more oil replenishment under heavy loads.
Answering any of the sitautions & challenges (not problems !) in this forum has to be seen in context that we (especially "I" don't know the specifics & most of the answers are generalising.
To answer what you have stated depends on a few factors.
My experience on using Timkens (& SKF's, GAMET precison etc) is for machine tools spindles (v.Large radial drills & boring machines).
In the company I served my apprenticeship all these were oil lubed (in some cases hydraulic oil was the lubricant - which surprises some people - hydraulic oil is very good at high speeds).
The company I worked for had elaborate systems for controlling the volume of oil delivered - too much causes overheating) & the system is dependant on the oil pump.
Since then I have worked on grease lubed Timkens - operating at over 4000/min - for precision machining of automotive parts using diamond tooling. Most of these had a very long life before change out.
In all cases I have used (or tried to use) the Kluber "sealed" system where you pre fill the bearing after first very carefuly degreasing it (this has to be done with synthetic greases)the amount of grease is critical, the spindle has to be run in & you then block up the greasing points. All of these were pre-loaded.
I originally did this for one breed of machines - saw it worked & used the method (very successfully) on other things) with adjustments to type of grease(speed, application etc) & pre load.
Pre loading bearings s a subject in itself - again each application is specific to itself. (Size, speed, load etc)
This is why bearing makers are loathe to advise unless they know all the factors, notably Barden can offer a variey of lubes for any bearing they supply. Machine tool builders have formats for the amount of pre-load that suit their product applications, which re generally pretty wide.
If you have had bearing failure attributable to lube type, lube failure, excess of lube, etc dont blame Kluber.
Kluber is not just one product or general purpose grease - they have many types & grades within each type, that can be tuned to one application.
They have great expertise in getting to the right one, especially high speed - high temp. You also have to follow the directions as regards amount of grease & de greasing before applying Kluber.
I dont work for Kluber or represnt them in any way, but their products have solved many issues that I have come accross
