more thoughts about needle bearings

[pamotorman]

Take a good look at a factory designed needle roller setup and you'll find in the case of DOHC and needle roller finger followers, hydraulic lash adjusters are used to keep everything in contact at all times. That reduces shock loadings of the needles so that they'll outlast the rest of the engine if maintained properly.
Same goes for a similar setup but built for more RPM, mechanical lash adjustment but still needle rollers running on the cam lobes. In this case there's extra springs on the rockers to keep the rollers on the cams when on the base circle.
Factory reliability of course. Proven technology by winning the Paris Dakkar many times.

I remember there were what were call "mouse trap springs" used on the rocker arms

[nhrastocker]

Thanks, but this still begs the question, why do we apparently have more reports of needle bearing lifter going bust than bushings ? Shock loads ?

my guess is they are too small for the load they bear but there is no room for larger ones

Load is always spread over the contact area. In case of a needle you always only have a limited contact zone. In fact it is only a line. The only way to increase the load bearing surface would be to have more needles acting on the same axle.
I do know one thing that will always kill a needle bearing and that is a shock load. Smash something with enough force into an equally hard surface and you will get an indentation. That indentation will cause vibrations and will hammer the needles and eventually destroy them.

Needle bearings having a limited contact area?
There will always be contact will all the needle bearings if the part is designed correctly and the diameter of the shaft is consistent with the ID of the bearing. The amount of needle bearings is defined by the design and size of the bearing and cage.

Your shock load theory is incorrect.
A properly designed needle bearing with the proper material, will absorb loads.
You just cannot go and purchase a commercial needle bearing made with inferior materials.

Explain to me how you get an indentation on a caged needle bearing assembly?
Most failures of caged needle bearings are due to lack of lubrication, too much clearance between the shaft and bearing, debris/foreign material or a poorly designed or incorrect selection of the needle bearing. There are other secondary failures that can be attributed to failure of the structure that holds the bearing in place, not the bearing itself. One example is when the lifter fork shaped end starts to spread.

[nhrastocker]

If you want to learn about needle bearing design, requirements and more, download the Koyo Needle Bearing Company catalog and read.
It has a lot of useful information.

http://www.neita.nl/pdf/koyo-torringtoncat.pdf

[jred]

I had bbc with a roller cam that I did for a customer, he bought a Herbert cam and a set of comp roller lifters it took a sh?t in about a year running on the street , we put in comp cam and a new set of lifters from comp , and again it went away in about a year ..

Not a lot of street uses but a weekend car for cruises and car shows and such.. my customer had bought a cam and roller lifters from Herbert and the lifters were some black cheap looking ones that were made by Herbert.. so on the third round we put it back together new cam and the Herbert lifters no problems to date and that was 5 years ago.. I took one of the comp lifters apart and have to that the axle diameter was quite a bit smaller than the lifters from Herbert .

It seems to me that the speed of the roller and the small axle and small needle bearings doesn't give very much contact area at any 1 time oh and the spring pressure was about 200 closed and 550 open..
look at all the problems that the ls engines are having with hyd roller lifters or at least down here I have repaired about 20 ls engine with the roller gone away and wiped out the cam..

I do believe that pin oiling or roller axle oiling is a good thing but believe that the axle is to small for longevity and higher spring pressures are playing havoc with the roller..

[Belgian1979]

my guess is they are too small for the load they bear but there is no room for larger ones

Load is always spread over the contact area. In case of a needle you always only have a limited contact zone. In fact it is only a line. The only way to increase the load bearing surface would be to have more needles acting on the same axle.
I do know one thing that will always kill a needle bearing and that is a shock load. Smash something with enough force into an equally hard surface and you will get an indentation. That indentation will cause vibrations and will hammer the needles and eventually destroy them.

Needle bearings having a limited contact area?
There will always be contact will all the needle bearings if the part is designed correctly and the diameter of the shaft is consistent with the ID of the bearing. The amount of needle bearings is defined by the design and size of the bearing and cage.

Your shock load theory is incorrect.
A properly designed needle bearing with the proper material, will absorb loads.
You just cannot go and purchase a commercial needle bearing made with inferior materials.

Explain to me how you get an indentation on a caged needle bearing assembly?
Most failures of caged needle bearings are due to lack of lubrication, too much clearance between the shaft and bearing, debris/foreign material or a poorly designed or incorrect selection of the needle bearing. There are other secondary failures that can be attributed to failure of the structure that holds the bearing in place, not the bearing itself. One example is when the lifter fork shaped end starts to spread.

When you have two circles that intersect, you have a very limited contact patch at the area where they touch. In a plain bearing, this contact area is a lot bigger. So the actual contact area in a needle bearing depends on how many needless you have around the axle (and the diameter of axle versus the diameter of the needles). So the diameter of the axle is a factor here as you can fit more needles around it.
In a typical u-joint the axle is big, the needles small so a lot of needles present to distribute load. The axle in a lifter is a lot smaller.

If a lifter comes off the lobe, and is then pounded back into it, the needle will cause an indentation in the surface. Next time needles go over that indentation you get vibration.

[Geoff2]

Warpspeed,
In case you hadn't noticed.......there seems to be just as many needle brg roller lifter failures with pressurised oiling, as there was without it.....

[Geoff2]

The Koyo info was a very interesting read. Oil viscosity versus load got a mention, so are thin 0w/20 oils too thin maybe for high valve spring pressures & breaking through the oil film??

The front wheel brgs & U joints are two examples of roller brgs that run for 000s of miles with minimal lubrication.

Harley Davidson used needle roller lifters for decades; they were only splash oiled & failure was rare.

Mouse trap [ hairpin valve springs ] are nothing new, they go back decades.

[Warp Speed]

Warpspeed,
In case you hadn't noticed.......there seems to be just as many needle brg roller lifter failures with pressurised oiling, as there was without it.....

In case you haven't noticed, there are many factors that lead to roller lifter failure. Your Harley bearing or u joint reference have NOTHING to do with the dynamics involved in valve train operation. Please change your narrative accordingly, as the current one holds no water! LOL

Just sayin'

[cjperformance]

The Koyo info was a very interesting read. Oil viscosity versus load got a mention, so are thin 0w/20 oils too thin maybe for high valve spring pressures & breaking through the oil film??

The front wheel brgs & U joints are two examples of roller brgs that run for 000s of miles with minimal lubrication.

Harley Davidson used needle roller lifters for decades; they were only splash oiled & failure was rare.

Mouse trap [ hairpin valve springs ] are nothing new, they go back decades.

A front wheel bearing or u joint is nothing like a solid roller lifter.
Many many manufacturers have used needle roller lifters for decades not just H.D. ,, but NOT ONE of those OE manufacturers use a lobe profile or spring pressure like what is being discussed here.

[Geoff2]

Warpspeed,
I do not need to change my narrative, certainly not to suit your agenda. I am well aware of the dynamics of the valve train. You should learn to read. My last post was about LUBRICATION, & all roller brgs, among them needle roller, u joint rollers, & wheel brgs require LUBRICATION.

[Geoff2]

CJperformance,
My point was/is that the brgs I listed are ALL roller brgs & ALL require lubrication. Some may require more than others, while some exist on very scant amount of lube & seem to survive just fine. A roller brg has a line of contact between the roller & the race, & all roller brgs share that COMMON feature.

[Geoff2]

From the Bosch Automotive Handbook, 3rd edition, page 275.

Rolling bearings.

Advantages:
- low static CoF
- Low maintenance
- Suited to permanent lubrication
- Low lubricant consumption

Disadvantages:
- Sensitive to impact loads
- sensitive to dirt

[Dan Timberlake]

The Koyo info was a very interesting read. Oil viscosity versus load got a mention, so are thin 0w/20 oils too thin maybe for high valve spring pressures & breaking through the oil film??

The front wheel brgs & U joints are two examples of roller brgs that run for 000s of miles with minimal lubrication.

Harley Davidson used needle roller lifters for decades; they were only splash oiled & failure was rare.

............

====================

The lubrication of rolling bearings (and gears) strives for elastohydrodynamic (EHD) lubrication, which is similar to our beloved hydrodynamic lubrication, but different.
Hydro.... depends on sliding to form a wedge.
Elasto...... , being rolling, has to climb up on the oil faster than it can leak out, like hydroplaning driving on a wet road. And small surface deformation so the "line" contact gets some width, and thus some area is also required.
Once established, both types are VERY powerful, capable of preventing metal to metal contact under really high loads. Mating surface roughness determines how thick the oil film must be.

Like tire rpm in hydroplaning, Roller rpm ( above some minimum rpm) determines when surfaces separate, and also how far.

Attached is an image from a top tier bearing manufacturer's lubrication tech info for the minimum operating viscosity to barely achieve EHD. Schaeffler/FAG
My pre-coffee estimate of roller assembly rpm being similar to crank rpm needs scrutiny and deeper consideration.

roller bearing lube.gif

But the "proper" viscosity is indeed higher than anything anyone is likely to pour into the oil filler hole. hole.http://media.noria.com/sites/archive_im ... able_2.gif
Once again, Hot Rodders insist on using mechanical devices in ways never intended.

Full rolling bearing lube tech doc is here-
http://www.schaeffler.com/remotemedien/ ... _de_en.pdf

[nhrastocker]

When you have two circles that intersect, you have a very limited contact patch at the area where they touch. In a plain bearing, this contact area is a lot bigger. So the actual contact area in a needle bearing depends on how many needless you have around the axle (and the diameter of axle versus the diameter of the needles). So the diameter of the axle is a factor here as you can fit more needles around it.
In a typical u-joint the axle is big, the needles small so a lot of needles present to distribute load. The axle in a lifter is a lot smaller.

If a lifter comes off the lobe, and is then pounded back into it, the needle will cause an indentation in the surface. Next time needles go over that indentation you get vibration.

First, there is no intersection,; it's called tangential contact and the amount of contact is defined by the design.
Like Warp Speed has said many times, the dynamics of a U-Joint cannot be compared to those of a lifter.
The size of the axle lifter is defined and chosen by the manufacturer and it varies from manufacturer to manufacturer.
In what surface would the needle cause an indentation? Vibration?

It boils down to the design of the lifter, the materials selected and the type of needle bearing selected.
If a manufacturer chooses and inferior bearing, expect a failure.

Turbine engines have needle bearings in all the rotating assemblies.
Their rotating internal speeds in their second stage, depending on the engine are from 12000 to 24000 RPM's constantly during operation.
Just imagine the loads and beating these bearings take during a 12 hour flight, several days a week or during the year.
They also run very light synthetic oils at operating temperatures exceeding 500 degrees C.
Turbine engines also have more operational loads and vibration when compared to a race engine.
Guess? Those needle bearings run for thousands and thousands of hours without failures.

Also, it is interesting why Jesel doesn't offer a bushing lifter.
If they were so great, they would offer one.
In my book, only Jesel and Morel are the lifters to use if you want reliability.

[Belgian1979]

I have morels, so that part is covered.

Anyway, I personally think you can have a situation with enough impact that the small needle can cause a dent in either the axle or in the wheel when the force is high enough.

Additionally to that, I agree that the u-joint has little comparison to a valve lifter.