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Sr. Member
Posts: 153
Reply with quote  #16 
Originally Posted by John from PA
Without knowing the age of this machine, and rethinking the situation, I would change my previous recommendation to try a synthetic and voice caution in using the Shell Omala suggested by Sinski.

Shell Omala S4 WE is an advanced synthetic heavy duty industrial worm drive gear oil formulated using specially selected polyalkylene glycol base fluids.  The issue, in an old machine, is polyalkylene glycols can attack conventional paints.  High quality epoxy paints are recommended.  There can also be some seal issues.  Omala S4 WE has been found to be satisfactory with nitrile and Viton seal materials, although Viton seals are preferred.  The Shell products also has some very specific procedures for change over to the product if you have been using a conventional lubricant. 

If this is an older machine, say 15 to 20 years or older, I really think you need to pursue making contact with the OEM and get their recommendations.  They can research paints, seal materials etc. and make sure you are using the best compatible lubricant.
I've received a rather cryptic response from the OEM which seems to suggest that typical oil is a mineral 220 or 320 cSt depending on temperature. A 460cSt is not recommended unless temperatures are "extreme" and even then only with an oil warmer due to effects on bearing lubrication.
John from PA

Sr. Member
Posts: 963
Reply with quote  #17 
To suggest a mineral based oil makes me think the sump temperature is less than about 80 deg C.  Above that and some special considerations come into play on the additive package withe the bronze gear.  

There is another good article on worm gear lubrication at   

You had previously mentioned very high levels of copper and tin in the oil analysis.  Typically these worm gears with a cast housing have some inspection ports that permit viewing the mesh area.  The downside, in your case, is when the casing is mounted on its side, the inspection port is a pipe plug and that often is the oil level.  Anyway have you made any attempt to look inside through whatever means may exist.  Since the gearbox, by your description, has seen years of service one has to consider that a bearing may be failing and that the contact is bad due to shaft movement from a failing bearing.  

Sr. Member
Posts: 75
Reply with quote  #18 
I'd be going with a 460 synthetic minimum for a worm, definitely not 220. Can't understand your OEM comments, unless they gave the problem to the office junior who looked up the wrong manual.

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