Small worm and worm gear at 30:1 reduction in housing containing 3.4 ounces of oil is wearing out worm gear very quickly. Worm rotates between 500 and 1500 rpm 24/7. Went from a Texaco 80W-90 EP oil to Mobil 634 to reduce wear, possibly phosphate comtamination with bronze. The kicker here is the transmission rotates around the machine axis at 100+ rpm and is forcing the oil against the back of the transmission housing. Concern about worm gears ability to move oil to the worm keeping the fluid film lubrication throughout the engagement. Any thoughts?

What spec does the OEM call for? May be ISO 460 or 680? Did it come with a PAG?
James

We designed and built it ourselves. The alignment is good and gear manufacturer recommended Mobil 634. My concern is the centrifigal force moving the oil away from the worm and depending on the worm gear to move enough oil to lubricate the worm throughout the contact. FYI, worm is verticle.

gear oils you are using have too much HOT sulfur and maybe caseing chemical wear I would look at perhaps a AGMA compunded oil ISO VG garde 460 with MOLY disulfide that has worked for me in the past.

bruce

Probably the safest thing to use would be a Worm Gear specific gear oil. They are compatible with the yellow metals found in worm gear applications and of a much higher viscosity than what you are currently using.

quote:

Originally posted by imarukee:
Small worm and worm gear at 30:1 reduction in housing containing 3.4 ounces of oil is wearing out worm gear very quickly. Worm rotates between 500 and 1500 rpm 24/7. Went from a Texaco 80W-90 EP oil to Mobil 634 to reduce wear, possibly phosphate comtamination with bronze. The kicker here is the transmission rotates around the machine axis at 100+ rpm and is forcing the oil against the back of the transmission housing. Concern about worm gears ability to move oil to the worm keeping the fluid film lubrication throughout the engagement. Any thoughts?

If you built gearbox yourself than you can modified it also. Have you thought of adding some type of guard (e.g. a bow shaped plate) on the back of the transmission housing that would "channel" the oil that swirls on the back of the transmission housing and splash it over gears? I don’t think you will be much better off with using different type of oil as you would be with this “modification”, providing you have room for this type of baffle.

Just a thought, how about increasing the volume of oil in gearbox?

Apply Rewitec nanocoating, a ceramic-like coating that protects metal surface of tooth flanks making the lubricant job more effective. It is applied in operation into the oil and it is effective for curing wear in any kind of gears and any metal alloy. The website is www.rewitec.us

I'm with LumSK, I would lean towards using an ISO 680 worm gear lubricant (AGMA 8C) or better still in my mind a semi-fluid grease (NLGI 00 or 000) with a heavy base oil viscosity (ISO 460-680) non EP. Due to the extremely small capacity you could I would fill the unit to 90-95% capacity allowing for thermal expansion.

Thanks for everyone's input. We are going with the Mobil SHC 634 as recommended by the gear manufacturer, Boston.

I think modifying the housing is a valid point. The thought is to add the resevoir to the backside of the housing, but I think the resevoir should be on the front side. This way centrifigal force will push the oil to the back of the box when it rotates, covering the gears.

The small oil capacity is also causing the drive to get extremely hot. The larger resevoir would help reduce some of the heat.

Can anyone recommend a semi-fluid grease for worm gear drive as mentioned by David?

This message has been edited. Last edited by: imarukee,

Mobilith SHC 007- NLGI # 00 lithium thickener w/ PAO ISO 460 base oil

And I don't even sell it

Thanks for the info.

Dear Imarukee,
We have had better performance recorded when Omega64, a semi solid grease (NLGI #00)was used in several similar gearboxes. This product is fibrous and stays between and lubricates the gears. You can get more info on the products if you will visit www.magnagroup.com. you can also write to them if you need to know the distributor details in Your area.
Best Regards
Collins David

I think you have use bronze in the worm. u know most worm gear contain bronze. The active S type EP may react with bronze and lead to heavy corrosion. I recommend u Mobil XMP or Mobil Glygoyle HE Series.

NLGI 000 Grease is good to , but it will result in hotter in gearbox since grease is more thick than oil. The load of the gera is bigger.

Dear Imarukee, As I review the posts here some basic questions are missing. How hot is the oil / case. I also think you need an oil analysis to determine if the wear is contamination related or a systemic failure. I would recommend a good lab such as http://www.bentlytribology.com

Imarukee,

I had a similar case in Pulp&Paper facility. We used a Mobilgear oil ISO 460. At some point when the load was high we had overheating oil thining an several problems. We tried several oils (including Mobilsynth). Results were better with synthetics, but the Mobilith SHC 007 solved the problem. The only issue we had is how to check the lubricant level, so we had to put a rod (like the ones for cheking engine oil) in the gearbox being careful to have it as far as possible from the gear.

Saludos

Shell, Chevron, and other oil suppliers make worm specific lubricants with an "oilyness" additive, usually animal fat.

The additive is hard to wipe off which prevents "dry" spots from developing in the areas of sliding contact present in worm screws.

You just need to find a supplier that can point you to one of them.