Chemical Activity Toward Copper of Universal Gear Lubricants

This test, which provides for  immersion  of a clean  copper strip in a  sample  of the  lubricant for a  prescribed  time  and  at a given  temperature, rates the  strip at the  end  of the test  as follows: “ At the conclusion  of the  test  the copper  strip  is removed, rinsed with sulfur-free  acetone and  inspected. The  degree  of discoloration of the  strip  is expressed  in one  of the  following  terms:

a.       None

b.      Stained

c.       Light peacock

d.      Dark  peacock

e.      Black.”

Sulfated Residue, Lead, Iron and Copper in Lubricating Oils

In this  methods, the sample  is completely  oxidized  by wet  ashing  with  concentrated  sulfuric acid, concentrated  nitric  acid and  hydrogen  peroxide, or  if  only iron and copper  are  to be  determined, by dry  ashing. To determine sulfated  residue, the  solution obtained by  wet  ashing  is  transferred  to a weighed  dish, evaporated  to  dryness, ignited at 775 degree C, cooled and  weighed. In determining lead, iron and  copper, the  solution resulting  from  the  wet  ashing is  mixed with  alcohol and  filtered  to give  a  precipitate  of  primarily  and  sulfate. This  precipitate  is  boiled  with  sodium carbonate and  then  precipitated  with  hydrogen  sulfide.

Iron  and  copper are  determined on  separate  aliquots  of the  filtrate  from  wet  ashing. The  iron is  separated  as the  hydroxide and  determined colorimetrically  as the  orange  ferrous  orthophenanthroline  complex,  while  copper  is  determined  colorimetrically  as the  yellow diethyldithiocarbamate  complex

Nonferrous Metal Rolling Gear Lubrication

Metals such  as aluminum, brass, copper etc., are  rolled  into  sheets or  other  shapes in  continuous rolling  mills designed  somewhat like those  found in steel  mills. Modern mills use circulating oils to lubricate the gear drives, pinion stands, and journal bearings. Either mild EP or MP gear oils of a noncorrosive nature can   be employed in such service. The  grade  of  oil  will depend  upon the speeds  of the gears  and  may  vary  from an  SAE  80  to an SAE  140. In  screw down  equipment  either of the above  type  of oils  or a straight  mineral  oil  can  be  used. Where  any  of the above  drives  are  through open gears, a residual  type  of gear  oil  containing  a  rust  inhibitor  and having  a viscosity  of 1000 to  2000 SUS at 210  degree F  should  prove  satisfactory. The  best  practice  is to  apply  such a lubricant automatically so as  to  insure a coating on  the  gears  at all  times.