Hydraulic fluid

Abstract

A method for reducing total wear-induced weight loss during wear-inducing operation of equipment, the method comprises a) providing a hydraulic fluid comprising a combination of an amount of zinc dithiophosphate and a quantity of magnesium salicylate, wherein said quantity of magnesium salicylate is from 0.001 to at most 1% wt and said amount of zinc dithiophosphate is from 0.01 to 1% wt. and b) operating the equipment using the hydraulic fluid under wear-inducing conditions that reduce the weight of the equipment. The hydraulic fluid is effective to produce a first total weight loss that is less than a second total weight loss that would be observed using a second hydraulic fluid comprising a quantity of calcium salicylate in place of said quantity of magnesium salicylate.

1 . A method for reducing total wear-induced weight loss during wear-inducing operation of hydraulic equipment, the method comprising: 
 a) providing a hydraulic fluid comprising a combination of an amount of zinc dithiophosphate and a quantity of magnesium salicylate, wherein said quantity of magnesium salicylate is from 0.001 to at most 1% wt and said amount of zinc dithiophosphate is from 0.01 to 1% wt.; and    b) hydraulically operating the equipment using the hydraulic fluid under wear-inducing conditions that reduce the weight of the equipment, the combination being effective to produce a first total weight loss that is less than a second total weight loss that would be observed using a second hydraulic fluid comprising a quantity of calcium salicylate in place of said quantity of magnesium salicylate.    
   
   
       2 . The method of  claim 1  wherein the first total weight loss and the second total weight loss are measured by Vickers V104C vane pump test under conditions comprising a test duration of 250 hours, a fluid temperature of about 66° C., a fluid outlet pressure of 35 bar (3.5 MPa), and a pump speed of 1450 revolutions per minute.  
   
   
       3 . The method of  claim 2  wherein the second total weight loss is six or more times greater than the first total weight loss.  
   
   
       4 . The method of  claim 1  wherein the hydraulic fluid includes a salicylate consisting essentially of magnesium salicylate.  
   
   
       6 . The method of  claim 4  wherein the magnesium salicylate has a magnesium content of more than 500% of the stoichiometrically equivalent amount of magnesium based on the amount of total acid present.  
   
   
       7 . The method of claim  22  wherein the magnesium salicylate has a magnesium content of more than 550% of the stoichiometrically equivalent amount of magnesium based on the amount of total acid present.  
   
   
       8 . The method of  claim 1  wherein the magnesium salicylate has a magnesium content of about 750% of the stoichiometrically equivalent amount of magnesium based on the amount of total acid present.  
   
   
       9 . The method of  claim 1  wherein step a) includes including in the hydraulic fluid from 0.001 to 5% wt of a compound according to the following Formula I:  
     
       
         
         
             
             
         
       
     
     in which R 1  and R 2  are each an alkyl of 3 to 6 carbon atoms; R 3 , R 4  and R 5  are each hydrogen; X is N and R 6  and R 7  are each an alkyl of 15 to 20 carbon atoms, or an acyl group derived from a saturated or unsaturated carboxylic acid containing 4 to 10 carbon atoms, at least one of R 6  and R 7  being an acyl group.  
   
   
       10 . The method of  claim 9  wherein step a) comprises providing a weight ratio of magnesium salicylate to zinc dithiophosphate which ranges from 1:5 to 1:100; and providing a weight ratio of magnesium salicylate to the compound of Formula I ranging from 1:0 to 1:50.  
   
   
       11 . The method of  claim 10  wherein step a) further comprises including in said hydraulic fluid at least one additive selected from the group consisting of pour point depressants, anti-foam agents, and demulsifiers.