AGMA-certification

[moideen]

To get the AGMA approval for the new gear box for the GEA Polacel for cooling tower, I asked the supplier for it. They told me they don't follow AGMA but can give me DIN and ISO. They also say that European brands don't follow AGMA, but from what I know, all makers should follow AGMA to make sure quality. Please looking advise…

 

[dgeesaman]

Oof, that's a deep subject. First, AGMA, DIN, and ISO does not "approve" any gearboxes that I'm aware of. (It's not like UL.) So in contractual language, a vendor should never offer an AGMA approved or certified gearbox. If they do, question their competence.

On a more practical level, gearboxes designed to AGMA practices and standards are serving in equally severe services as DIN and ISO designed gearboxes. What does vary, from standard to standard and manufacturer to manufacturer, is the robustness of that rating (which comes from the honesty of the inputs they use in calculating the rating and the relevance of those assumptions to your particular use case). I've tested gearboxes built to DIN standards that were very robust and others that were junk. I've also competed against AGMA rated gearboxes that show surface pitting after one year even though they claim the same rating as our product, which has sufficient surface fatigue rating that it will not pit for many years. That competitor, by the way, considers pitting to be a normal wear behavior and not an 'end-of-life' event.

This leaves you to choose based on experience and/or expertise. There are gear design consultants who can probably assist if buying on experience is not an option. I realize that not many facilities keep people and knowledge around long enough to see the difference between good and bad design gearboxes - heck it's a great accomplishment in many cases to simply have the end user performing basic maintenance and operating within the design specifications.

I've seen contracts that require the vendor to supply a fully detailed rating calculation with a PE stamping. The PE generally has no gearbox design experience and signs based on a cursory review that the major inputs (power, RPM, etc) align with the project. Even if the PE was expert in gear design, it would be a deeply detailed audit ito try and confirm the inputs. So that method doesn't seem to add value, from my perspective. And there are only so many gearbox suppliers who will provide those calculations, since all of those details can be considered highly proprietary data.

I'd love to brag that good, reputable gearbox suppliers will always provide their gearboxes with the same robustness over the lifespan of the company. I won't. I think it's often true but mistakes can be made and ownership/management can alter their commercial approach at any time.

 

[mfgenggear]

Op
The gear box is designed for imput torque and rpm. And output rpm and torque. All the details are designed and manufactured based on that requirement. Generally a gear box must be test to runs many hours
With out failure. The details are certified to either usa or other specifications. AGMA , Iso or other.
I am strong in the details , each detail is designed to meet or exceed many different specifications including AGMA and ISO.. gear box rating is based on all of above.
Ask for all documentation on inspection and heat treat reports.

 

[moideen]

Oof, that's a deep subject. First, AGMA, DIN, and ISO does not "approve" any gearboxes that I'm aware of. (It's not like UL.) So in contractual language, a vendor should never offer an AGMA approved or certified gearbox. If they do, question their competence.

On a more practical level, gearboxes designed to AGMA practices and standards are serving in equally severe services as DIN and ISO designed gearboxes. What does vary, from standard to standard and manufacturer to manufacturer, is the robustness of that rating (which comes from the honesty of the inputs they use in calculating the rating and the relevance of those assumptions to your particular use case). I've tested gearboxes built to DIN standards that were very robust and others that were junk. I've also competed against AGMA rated gearboxes that show surface pitting after one year even though they claim the same rating as our product, which has sufficient surface fatigue rating that it will not pit for many years. That competitor, by the way, considers pitting to be a normal wear behavior and not an 'end-of-life' event.

This leaves you to choose based on experience and/or expertise. There are gear design consultants who can probably assist if buying on experience is not an option. I realize that not many facilities keep people and knowledge around long enough to see the difference between good and bad design gearboxes - heck it's a great accomplishment in many cases to simply have the end user performing basic maintenance and operating within the design specifications.

I've seen contracts that require the vendor to supply a fully detailed rating calculation with a PE stamping. The PE generally has no gearbox design experience and signs based on a cursory review that the major inputs (power, RPM, etc) align with the project. Even if the PE was expert in gear design, it would be a deeply detailed audit ito try and confirm the inputs. So that method doesn't seem to add value, from my perspective. And there are only so many gearbox suppliers who will provide those calculations, since all of those details can be considered highly proprietary data.

I'd love to brag that good, reputable gearbox suppliers will always provide their gearboxes with the same robustness over the lifespan of the company. I won't. I think it's often true but mistakes can be made and ownership/management can alter their commercial approach at any time.

thanks for the comments.
I recently had an experience with an Indian brand, Paharpur Cooling Tower, which has four units placed at our plant. Within six months, the gearboxes began to experience a variety of problems, including oil seal leakage, vibrations, and damaged tower blades during full-speed operation. However, the mechanism functioned properly at lower speeds. The gearbox was identified as the underlying source of these issues.

In contrast, I have Evapco cooling towers at another plant that have been operational for more than nine years with no difficulties with the gearbox or other tower components. After examining the selection sheets of both manufactures, I discovered that Evapco specifically follows the AGMA code for gearboxes.

This event made me more cautious. For future cooling tower requirements, I will prioritize ensuring that the gearbox meets AGMA specifications.

As I said in my first post, the new Polacel cooling tower meets DIN and ISO requirements but not AGMA. My question was based on the context.

 

[3DDave]

Almost never is reliability related to a claim about following a standard nor is following a standard a guarantee of suitability or durability as they might follow the wrong standard or the wrong criteria for a standard applied to your requirements.

What matters is what the company does when you call them up and say their gearboxes are leaking and appear to be causing severe vibration issues.

What I would prioritize is not buying from a maker that doesn't have good answers for why their product appears to have failed.

 

[mfgenggear]

Op
Have a local gear shop tear down and inspect the gear box. Have them take pictures as it is being dis assembled.
Have the gears inspected to which is specification the gear box manufacture specifies. Inspect the bearings for damage.
There are many factors for a bad gear box. Poor ground surfaces, un balanced details , eg gear shafts or shafts. Under rated or improper bearing installs. The precision of gear box case it self. Improper gear manufacture with excessive run out.
Or bad total composite error.
While the gear box is running before disassembling verify the vibration.
The installation has be level and in line with the motor. And the out put shaft. an improper install can cause vibration and damage.

 

[MintJulep]

Nothing to do with AGMA vs. ISO or DIN.

It's manufacturer competence and quality.

 

[mfgenggear]

Not correct, gears ,spur, bevel, helical have to inspected and certified to a standard. The gear box has to be tested by the manufacture , depending on the industry. Or its function.

 

[mfgenggear]

Even commercial gears have to be inspected and certified.