Method for reducing wear and metal fatigue during high temperature operation of a gear set

Abstract

Disclosed is a method for reducing wear and metal fatigue during high temperature operation of a gear set, which method comprises operating the gear set with a dispersed hydrated sodium borate composition.

What is claimed is:  
     
         1 . A method for inhibiting gear damage, as measured by reduced wear and metal fatigue associated with ridging and pitting, during operation of a gear set at a temperature of at least 163° C., which method comprises operating said gear set with a dispersed hydrated sodium borate composition comprising: 
 (a) a hydrated sodium borate  
 (b) a dispersant, and  
 (c) an oil of lubricating viscosity,  
 wherein the dispersed hydrated sodium borate composition is characterized by a sodium to boron ratio of from about 1:2.75 to 1:3.25 and a turbidity value of no more than 300 ntu.  
 
     
     
         2 . The method according to  claim 1 , wherein the dispersed hydrated sodium borate has a sodium to boron ratio of from about 1:2.9 to about 1:3.1  
     
     
         3 . The method according to  claim 1 , wherein the dispersed hydrated sodium borate has a sodium to boron ratio of about 1:3.  
     
     
         4 . The method according to  claim 1 , wherein the dispersed hydrated sodium borate has a hydroxyl to boron ratio of from about 0.5:1 to 2.0:1.  
     
     
         5 . The method according to  claim 4 , wherein the dispersed hydrated sodium borate has a hydroxyl to boron ratio of from about 0.7:1 to 1.8:1.  
     
     
         6 . The method according to  claim 5 , wherein the dispersed hydrated sodium borate has a hydroxyl to boron ratio of from about 0.8:1 to 1.6:1.  
     
     
         7 . The method according to  claim 1 , wherein said composition further comprises from about 0.001 moles to about 0.11 moles of a water soluble oxo anion per mole of boron atom.  
     
     
         8 . The method according to  claim 7 , wherein said water-soluble oxo anion is selected from the group consisting of nitrate, sulfate, carbonate, phosphate, pyrophosphate, silicate, aluminate, germanate, stannate, zincate, plumbate, titanate, molybdate, tungstate, vanadate, niobate, tantalate, uranates, isopolymolybdates, isopolytungstates, heteropoly-molybdates, heteropolytungstates, and mixtures thereof.  
     
     
         9 . The method according to  claim 1 , wherein said dispersant is selected from the group consisting of a polyalkylene succinimide, a polyalkyene succinic anhydride, a polyalkylene succinic acid, a mono- or di-salt of a polyalkylene succinic acid and mixtures thereof.  
     
     
         10 . The method according to  claim 1 , wherein said composition comprises 2 to 40 weight percent of said dispersant, based upon the total weight of the composition.  
     
     
         11 . The method according to  claim 1 , wherein said composition further comprises 0.2 to 10 weight percent of a detergent, based upon the total weight of the composition.