Gear oil that meets AGMA 5EP for blower

[TheOldHokie]

Sorry to resurrect this old thread, but I may be able to add some useful info. The place to go for worm gear drive lube is Ariens. They carry several lubes specific to worm gear drives. They have the AGMA 5EP and PAG 220 lubes in pint and quart sizes. (Ariens gear lubes)

If you use the blower a lot and work it hard, I would not use 80W90 or any other general gear lube. Worm gear drives are special. Spur and helical gears in transmissions, rear ends and final drives use involute spline teeth that roll over each other with no sliding. In a worm gear drive, as the worm gear rotates it slides across the tooth face of the driven gear. This creates much higher pressures and temperatures than spur and helical gears experience. The sliding action also makes it harder to keep an oil film between the gear teeth. The tooth face on worm gears typically runs at about twice the temperature above ambient than spur and helical gears. The minimum viscosity recommended for most worm gear drives is ISO 220 and everyone I’ve ever seen calls for EP additives. There are some compounded oil recommendations below 220 out there, but let’s keep this short. Most industrial drives use oil with a higher base viscosity than 220, but they’re running at higher ambient temps, higher rpm’s and much longer run times than snowblowers. My horizontal band saw uses a worm drive and specs a 600 weight oil.

The reason the manufacturers are willing to put 80W90 alongside the AGMA 5 and PAG 220 recommendation is they know the 80W90 gear oil will get you past the warranty period and will likely last the life of the blower given the cold ambient temps and low hours these units experience.

But if you regularly slog through two feet of snow down a 600 foot drive, go get the correct oil. There’s a reason Ariens sells all these oils.

Let me clear one thing up.

You started real good and had you simply stated that worm gears operate at much higher contact pressures thsn spur and helical gears requiring special lubricants you would have been 100% correct.

But the notion that spur and helical gears dont slide in contact is 100% wrong. A simple involute spur gear is in sliding contact at every point in engagement except when the contact point is at the pitch circle. The surface speed difference is greatest at initial engagement where the contact point is well outside the pitch circle and diminishes as the gears rotate and the contact point moves inward toward the pitch circle. When the teeth are fully meshed the contact point is at the pitch circle, the rolling surface speeds are equal, and there is no sliding component. As the gears continue to rotate the contact point moves outward again away from the pitch circle and the process is reversed.

Helical gears are more complex but the same principle applies. The helical design also increases both the sliding effect and tooth loading just like worm gears.. Spiral bevel gear sets and hypoid gears in particular are subject to very high sliding loads which is why EP additives providing API GL5 level perfornance are used/required in differentials.

Here is a very simplified analysis of sliding action on straighr cut involute spur gears.

https://involute.pro/fileman/Uploads/sliding%20velocity.pdf

Now back to your regular programming.

Dan

 

[North Idaho Wolfman]

I see we have another OIL THREAD!

 

[TheOldHokie]

I see we have another OIL THREAD!

No,. This is now a thread on gear geometry and operation


Dsn

 

[Quarencia]

No,. This is now a thread on gear geometry and operation


Dsn

No. It’s a thread about oil and you’ve kinda missed that point. Yes, you’re right, there is a very small amount of sliding for involute gear teeth when the contact point is off the pitch line, which is less than negligible when compared to a worm gear drive. The point I was trying to make for the OP or anyone else who stumbled on this thread, without getting into the weeds of gear geometry, was:

1. First and foremost, where to get the oil spec’d for his snowblower - since no one actually answered that question
2. Provide a rudimentary explanation of why worm gear drives are special
3. To make the point that worm gear drives may warrant getting oil actually formulated for them
4. Why it’s reasonably OK just going with the 80w90 if one is so inclined for a snowblower

I was just trying to be helpful to the OP and anyone else who stumbled on post. And this discussion of gear tooth design characteristics isn’t conducive to the OPs question.

 

[TheOldHokie]

I was just trying to be helpful to the OP and anyone else who stumbled on post. And this discussion of gear tooth design characteristics isn’t conducive to the OPs question.

That was exactly the point I was making WRT your introduction of (bogus) gear tooth action. As I said in my post - you should have stopped after the first paragraph.

BTW - AGMA dropped all recommendations for use of EP additives in worm drives with the adoption of AGMA 9005-D94 in 1994. That decision is now left to the OEM to make based on gearbox materials and the application.

Dan