FE Power Forums
FE Power Forums => Non-FE Discussion Forum => Topic started by: frnkeore on March 13, 2020, 01:57:43 PM
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Knowing that smaller diameter retainers = less weight, what are the limits to how small in diameter that the retainers can be to spring diameter and is it based on mean spring diameter or outside diameter?
Or, is there any reason to have a retainer, larger than the mean diameter of the spring, itself? Assuming a good spring ID to retainer fit.
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I'm surprised that there are no opinions on this.
No one specs their retainers for the springs they use?
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Frank, I have seen them significantly smaller many times and they work. The weight savings would be minor as is is a savings in the thinnest part of the retainer. Looks a little goofy to me, so I don't do it
I would much rather have a tool steel ot Ti retainer that fit the spring and/or run a smaller diameter spring if I want to save more. Beehives work great for that reason and more
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1.500 titanium light weights on 1.625 springs.
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This is what mine looks like. Titanium retainers that are smaller than the valve spring. I did not build this engine it came from the builder this way.
Seat 320# open 850#
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There's going to be a industry standard to it. Most retainers are sized according to the inner diameter of the outer spring and the outer diameter of the spring itself. The pictures these guys are putting up are about normal.
Here's another pic, 1300 lbs open pressure with 400 lbs seat. PAC 1.525" spring and PAC titanium retainer.
(https://live.staticflickr.com/65535/46760219115_1fd418ce68_c.jpg)
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Just run a beehive.
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There's going to be a industry standard to it. Most retainers are sized according to the inner diameter of the outer spring and the outer diameter of the spring itself. The pictures these guys are putting up are about normal.
Here's another pic, 1300 lbs open pressure with 400 lbs seat. PAC 1.525" spring and PAC titanium retainer.
Brent, do you mean that the industry is working on a standard or, that there is one and I will have to find it?
I know that you need to locate the spring on it's inside diameter, both top and bottom (if there is room on the bottom) but, I was hoping to find a real world, proven minimum size, based on spring diameter and wire size.
At this point, I can't see why the retainer would need to be more than the mean diameter of the outer spring, if the inside diameter is within ~.005 of the spring, assuming the retainer is strong enough for the spring pressure used.
I'm a machinist and I like dimensions, rather than how it might look.
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It's an industry standard.
Any retainer will not fit any spring, obviously. When you buy a spring, the spring manufacturer will have a reference for a preferred steel, tool steel, or titanium retainer. Some manufacturers, like Comp or Manley, will have retainers that are made for other brands. You don't have too much leeway here, because there are 3 critical dimensions that have to be held: the fit between the inner spring inner diameter and the retainer, the fit of outer spring inner diameter and the retainer, and the OD of the retainer versus the spring diameter. You won't find much variation, because it's already been engineered to work with specific applications.
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>When you buy a spring, the spring manufacturer will have a reference for a preferred steel, tool steel, or titanium retainer.
This. Buy the parts all together - springs, retainers and locks. SHopping around is false economy, unless you know the exact specs required for the springs. And/or you have a lathe.
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So then, no one knows what the industry standard is, the tolerance for that standard or, the engineering behind it?
There are a lot of variables, when it comes to the spring and retainer fit but, even opinions, many of them based on "what is done" have been few and I've asked this on another forum with about the same results.
Let me ask this, are there any documented cases of retainer or spring failure, based on the outside diameter of the spring/retainer fit (not ID fit)?
There are a few types of retainers out there, 4140, titanium and tool steel and there are drilled and scalloped styles. What I'm interested in is, what is the engineering behind them and the safe limits. I would also like to know what the first signs of failure are.
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I honestly don't understand what you're trying to do. There's plenty of engineering behind it and most of it will depend on FEA and testing, along with a myriad of other variables, not stopping short of natural frequencies. It will vary from spring to spring and retainer to retainer.
The retainer size is based on the spring diameter. The limit is when it fails. Not trying to be sarcastic, but that's the limit, and it has to be determined in FEA or testing, or both.
The spring I showed above is a PAC 1359 with a PAC R508 retainer. 1.522" spring OD. Retainer OD is 1.365". That means you have .079" of spring hanging off each side.
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I honestly don't understand what you're trying to do. There's plenty of engineering behind it and most of it will depend on FEA and testing, along with a myriad of other variables, not stopping short of natural frequencies. It will vary from spring to spring and retainer to retainer.
The retainer size is based on the spring diameter. The limit is when it fails. Not trying to be sarcastic, but that's the limit, and it has to be determined in FEA or testing, or both.
The spring I showed above is a PAC 1359 with a PAC R508 retainer. 1.522" spring OD. Retainer OD is 1.365". That means you have .079" of spring hanging off each side.
Brent,
I'm trying to understand the criteria of the retainer design. I thought between this forum and Speed Talk, I could find someone that might know how they are design and where the limits are.
You offer a spring and retainer size but, will that spring/retainer fail if the retainer is 1.300 in diameter, if so, how will it fail and how long will it take to fail? Is the retainer based on outside diameter or mean spring diameter (center point of pressure).
You didn't give the wire size but, if the retainer is some other diameter than above and if it is the mean diameter of the spring, will it fail if so, how will it fail and how long will it take to fail?
What is the minimum radius that the locator cuts for springs should be and the minimum thickness per spring pressure, for the different materials?
That's what I'm looking for answers to.
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It varies from application to application is what I’m trying to tell you.
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It varies from application to application is what I’m trying to tell you.
And that is what I'm try to understand, why.
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It varies from application to application is what I’m trying to tell you.
And that is what I'm try to understand, why.
Because material strengths vary. Because there are different sizes of retainer/lock combos, a 10° lock takes up more real estate than a 7° lock. Because spring wire can be round, ovate, etc. Because a 4000 rpm spring has different properties than a 9000 rpm spring. You're not going to be able to come up with a one-size-fits-all rule.
Manley's 22431 spring will work with several of their retainers. It's a 1.550" OD spring. Their Super 7 TensileMax retainer is 1.420". Their H13 10° tool steel retainer is 1.440". Their 10° titanium retainer is 1.500". Tons of variables that can't be tied down to one specific rule.
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https://www.hotrod.com/articles/hrdp-1011-what-you-need-to-know-about-valvesprings/
https://www.enginelabs.com/engine-tech/engine/valve-spring-tech-overview-of-valve-spring-design-dynamics/
https://www.hotrod.com/articles/hppp-0902-comp-cams-valve-spring/
Springs vary a lot, depending on the wire diameter, wind, material, associated assembly (free, double w/damper, conventional, behive, etc), spring rate and other factors. Then the cam comes in to hammer the spring and all kids of things start to happen based on lobe design and such. So the loads on the retainers can vary a lot. And the type of material used in the retainer varies, which also changes the design. Titanium is light weight, but under certain conditions the spring can shred the retainer because titanium is a soft metal. Retainers will - I imagine - require a certain Rockwell hardness depending on the end use. Too soft or too hard can both cause fatigue failures.
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Retainers will - I imagine - require a certain Rockwell hardness depending on the end use. Too soft or too hard can both cause fatigue failures
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Falcon,
Thank you for the links but, they don't cover retainer size, only some stuff on keepers.
I'm a retired machine shop owner (still have the shop) that did aircraft work, mostly. For 4130 and 4340 AQ (aircraft quality) steel, the industry standard hardness is 38-42 RC for the best hardness to fatigue ratio and all inside cuts must be generated with a radius, as described by the engineer that designs the part. But, before that, the part must be rough machined and then heat treated, before finished machined. They are then MPI inspected and plated, to be a finished product.
I can only hope that retainers are made to those standards.
Brent,
Are you saying the the keeper size dictates the retainer diameter???
Again, all I'm asking at this time, is the minimum retainer size for a given spring diameter and wire size. I like to use the mean diameter as that reflects both OD & ID of the outer spring. Multiple enter springs are already, fully covered so it's not a issue.
I was hoping to get a real life answer here but, it looks like I need to talk to cam and spring manufacturers.
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Retainers will - I imagine - require a certain Rockwell hardness depending on the end use. Too soft or too hard can both cause fatigue failures
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Falcon,
Thank you for the links but, they don't cover retainer size, only some stuff on keepers.
I'm a retired machine shop owner (still have the shop) that did aircraft work, mostly. For 4130 and 4340 AQ (aircraft quality) steel, the industry standard hardness is 38-42 RC for the best hardness to fatigue ratio and all inside cuts must be generated with a radius, as described by the engineer that designs the part. But, before that, the part must be rough machined and then heat treated, before finished machined. They are then MPI inspected and plated, to be a finished product.
I can only hope that retainers are made to those standards.
Brent,
Are you saying the the keeper size dictates the retainer diameter???
Again, all I'm asking at this time, is the minimum retainer size for a given spring diameter and wire size. I like to use the mean diameter as that reflects both OD & ID of the outer spring. Multiple enter springs are already, fully covered so it's not a issue.
I was hoping to get a real life answer here but, it looks like I need to talk to cam and spring manufacturers.
Absolutely. A larger or smaller hole in the retainer affects the strength.
I know what you're asking for, but there's not a direct answer to it, because it depends on too many things. What material? What angle? Did you see my post above where one retainer was 1.500" and the other was 1.420"?
You're gonna drive me to drinkin', Frank.
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Retainers will - I imagine - require a certain Rockwell hardness depending on the end use. Too soft or too hard can both cause fatigue failures
.
Falcon,
Thank you for the links but, they don't cover retainer size, only some stuff on keepers.
I'm a retired machine shop owner (still have the shop) that did aircraft work, mostly. For 4130 and 4340 AQ (aircraft quality) steel, the industry standard hardness is 38-42 RC for the best hardness to fatigue ratio and all inside cuts must be generated with a radius, as described by the engineer that designs the part. But, before that, the part must be rough machined and then heat treated, before finished machined. They are then MPI inspected and plated, to be a finished product.
I can only hope that retainers are made to those standards.
Brent,
Are you saying the the keeper size dictates the retainer diameter???
Again, all I'm asking at this time, is the minimum retainer size for a given spring diameter and wire size. I like to use the mean diameter as that reflects both OD & ID of the outer spring. Multiple enter springs are already, fully covered so it's not a issue.
I was hoping to get a real life answer here but, it looks like I need to talk to cam and spring manufacturers.
Absolutely. A larger or smaller hole in the retainer affects the strength.
I know what you're asking for, but there's not a direct answer to it, because it depends on too many things. What material? What angle? Did you see my post above where one retainer was 1.500" and the other was 1.420"?
You're gonna drive me to drinkin', Frank.
As a military guy, I wish I had not only a MIL standard, but adherence to it across manufacturers that had to meet common interchange requirements. Unfortunately, even though we say the engineering and product development is far better than it ever has been, and it is, you won't find those common standards, you may find rules of thumb that work across manufacturers, but in the end, just so many differences in manufacturing and material treatment
I think the best thing is to keep things small, think about managing harmonics and weight, and try not to push individual components to the edge. If the retainer needs to be small, find a design that meets the requirements that is small. It would be handy if it was different, but it just is what it is
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I used to be a QA guy in a manufacturing co., so I get your deal on MIL-SPEC things and engineering prints, material specifications and such.
My Howards catalog has 13 moly retainers listed and 9 titanium