metal compatibility roller rocker conversion
metal compatibility roller rocker conversion
(OP)
We are designing a rocker conversions for a SOHC race engine. The operation is via finger follower style rocker with 2 rollers under the cam and one on the tip for the valve stem. I need help to find the best material compatibility for the rollers and pins. The cam roller runs directly on a needle bearing so I was thinking something like case hardened 8620 for both the roller and pin would be OK? Cam it self I'm not sure of exact grade, i think is 41xx... and induction hardened. Geometry and cam is all sorted we have spent a great deal of time and development into getting it designed correctly.
My main concern is the tip roller which runs directly on the pin with no bearing, similar to all your typical v8 style roller rockers and I need to find the best material and hardening process for these two components. Iv heard dissimilar metals are usually better. This is only splash fed with engine oil, i have included into the design some little oil tracks in the sides of the body to promote oil down to the pin.
the cam roller is 26mm x 10mm wide with 2mm open cage needle running on a 10mm shaft (pin)
the tip roller is 13mm x9mm wide running directly on a 5mm pin
Thoughts and comments greatly appreciated.
My main concern is the tip roller which runs directly on the pin with no bearing, similar to all your typical v8 style roller rockers and I need to find the best material and hardening process for these two components. Iv heard dissimilar metals are usually better. This is only splash fed with engine oil, i have included into the design some little oil tracks in the sides of the body to promote oil down to the pin.
the cam roller is 26mm x 10mm wide with 2mm open cage needle running on a 10mm shaft (pin)
the tip roller is 13mm x9mm wide running directly on a 5mm pin
Thoughts and comments greatly appreciated.





RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
ISKY is offering roller rockers with bushings for some extreme applications due to bushings' superior overload carrying capabilities.
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
INA catalog 307 is what I was referring to.
I do no know if there is an online equivalent, but suspect there is. This says something similar will be available November 2012
http://www.fag.com/content.fag.de/en/branches/indu...)
There is a section dedicated to the design of shafts that needle bearings will roll directly against
Materials for rolling raceways.
Light duty applications successfully run the needles on some pretty basic, soft steels.
But Since hard working ball/roller bearings (Harley and oher MC crankpins) need a case depth of 1.5 mm or so, I'd anticipate hardening 3 mm of the 5mm shaft - might as well consider it thru hardening
INA lists thru hardening steels - DIN 17230 eg 100Cr6 ( same as 52100 maybe)
Surface hardness 670 to 840 HV is required, with hardness >550HV at depth based on load and rolling element ( needle ) diameter.
Nitriding is generally too shallow to work. Chrome plate is out.
the geometry ( roundness, smoothness, cylindricity, clearance ) for use as a bearing are all specified.
What the shock loads are, and whether the shaft/race can "take it" is another story
RE: metal compatibility roller rocker conversion
thank you for the input, the roller I am most concerned with has no bearing it runs directly on the shaft and its the material and hardness for this roller follower and shaft Im looking for help with.
I have received help from SKF for the bigger roller and shaft which does have a needle bearing and we have gone with a case hardened steel for both so at this stage I have a starting point to try.
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
Steel on steel is a bad start, hard or not.
Skimpy lubrication supply makes it worse.
Likelihood of starting from zero rpm makes it harder to initiate or maintain hydrodynamic lubrication, which makes it even worse.
Some plating or coatings might help. I believe Honda used to nitride their con rod pin ends when the attempted a steel-on-steel full float, and it was common to find the rod and pin galled to some degree.
Leaded bronzes are better at surviving marginal lubrication than the stronger bronzes.
RE: metal compatibility roller rocker conversion
Tekton
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
e21jps,
If cost is no object, then consider cold-worked Haynes L25 (cobalt alloy). I have had good experience with this alloy (also called Haynes alloy L-605) in challenging boundary lubrication applications. Metal-to-metal galling resistance at elevated temperatures is very good.
Dick
RE: metal compatibility roller rocker conversion
Would you suggest both pin and bush utilise the same cobalt alloy, or should dissimilar materials be used - - if so in which positions?
I asked similar questions of Tmoose regarding his Nov 5th suggestion of using leaded bronze, presumably the bush, but he may not have an answer - - does anyone else have suggestions please?
Tekton
RE: metal compatibility roller rocker conversion
http://www.buntingbearings.com/index.html?gclid=CN...
http://www.buntingbearings.com/data.html
http://www.anchorbronze.com/c93200.htm
"C93200 is suitable for bearings, bushings having medium loads and speeds with adequate lubrication".
SAE 660 Bearing Bronze , High Leaded Tin Bronze , 83-7-7-3 , ASTM B 505 , ASTM B 271.
A little lead eases manufacturing. A little more buys better resistance to galling when lubrication is poor. "Too much" can cost too much strength.
RE: metal compatibility roller rocker conversion
My experience with using L-605 is both the pin and the bushing in a variable nozzle mechanism for a turbocharger. I believe the alloy was developed for similar pin and bushing applications in the variable exhasut nozzle mechanisms of fighter jet engines.
I also used this alloy to solve a valve to valve guide wear issue for a large engine (CAT 3600 series) exhaust gas bypass valve. I don't really know of any other commercial applications, or how the material may be purchased other than bar stock.
See link for info about New Hampshire bearings.
The big advantage of L-605 is the high temp dry anti-galling properties. It may not be the ideal cost material for your application, but it would very likely work from a technical stand-point.
Dick
http://www.nhbb.com/reference/rod-ends-bearings/be...
RE: metal compatibility roller rocker conversion
Our application differs from the OP's in that we intend swaging 5mm od hollow pins into either end of the rocker arms, one to support an approximately 15mm od roller acting on the camshaft lobe, the other an approximately 8mm od roller acting on the valve stem tip
My suspicions are that a C93200 high leaded tin bronze bushing and complementary pin would suit the valve stem tip roller assy, but may not the higher rpm camshaft lobe roller depending on Anchor Bronze & Metals Inc. definition of "medium loads and speeds"
While L605 may also be suitable, I expect its cost effectiveness will suffer due to the materials required to meet the extreme operating temps and minimum lubrication of its design brief
Tekton
RE: metal compatibility roller rocker conversion
http://www.buntingbearings.com/data.html
RE: metal compatibility roller rocker conversion
Whit any type of hertzian contact, like that of your camshaft roller follower or rocker roller tip, you should always try to equalize the contact stresses in both parts. With the contact between the roller follower and cam lobe, the roller follower will typically have a smaller radius of curvature than the cam lobe, except for contact across the nose of the cam lobe, and will also be subject to a greater number of load cycles than the cam lobe due to its smaller circumference. To minimize friction losses at the roller follower, it is best to have rolling contact between the cam and roller, and to have sliding contact at the much smaller radius interface between the roller and rocker pin.
The same applies with the contact at the rocker roller tip and valve stem. The reversing rolling contact between the roller tip and valve stem, produces less friction loss than the sliding contact at the smaller radius contact between the tip roller ID and the rocker tip shaft.
RE: metal compatibility roller rocker conversion
I recently got far enough along with my OHC design to assign dimensions to my "fingers" and come up with ballpark worst-case tensile and shear stress requirements. It looks like I could get away with easy-machining 4130 (off-the-shelf wrought bar at about 30 -32 Rockwell-C). Comments?
RE: metal compatibility roller rocker conversion
Anyone have thoughts on this combo??
RE: metal compatibility roller rocker conversion
http://www2.mae.ufl.edu/arakere/docs/STLE_spall_1....
RE: metal compatibility roller rocker conversion
-Tony Staples
www.tscombustion.com
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
Maybe the tribological nightmare of skimpily lubricated steel-on-steel has proven to survive just fine in this application, but substitution of "ceramic" balls, still running on 52100 races, immediately brings life improvements related to disagreements that go on at the secret ball/race interface. The weaker the ElastoHyroDynamic lubrication, the more impressive the resistance of the mixed material combo to wear and damage becomes.
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
RE: metal compatibility roller rocker conversion
Springs will be about 250 lb. seat and 575 lb. open (about .625" lift). Follower ratio will be within a whisker of 1:2. Maximum negative acceleration of lobe profiles will be limited to about 2.5 x 10^(-4) inches per cam degree squared. I'm building the engine (blown alky) to have good power up to at least 10,000 RPM.
RE: metal compatibility roller rocker conversion
Neither the EZ-Roll nor EZ-Max lifters have internal oiling- "splash" is fine for all but extremely severe applications (1,300 lb. springs, etc.), in which case "dedicated" oil supply to the axle is recommended (but merely "aimed" near the axle is sufficient).