The Navy Gear Wear Tester

The Navy Gear Wear Tester is described in Federal Methods 791, Methods 335. The  equipment  makes  use  of  small  brass and  steel  gears,  but  Ninos  has  also  used  mating  gears  of other metals, such  as  brass on  stainless  steel, Phosphor  Bronze, and  ST Aluminum   on  SAE     4130 steel  and  SAE B-1112  steel  against  stainless  steel.

In  the  test  two  helical  gears  of  dissimilar  metals, each  approximately  one half inch  in  diameter are  rotated  together  as the  driving  motor  delivers a simple  harmonic motion     of 4.0  inches  amplitude  and  40 cycles per minute, through a  crack  to  the  upper  brass gear. This gear  oscillates  approximately  one  revolution while  a torque load of about  three  and  one  half inch pounds  is applied to  the  test  gears by  means  of a seven  pound  weight. The  gears  are  oscillated  for the  desired  number  of  cycles, or until gear  tooth  failure  due  to  excessive  wear  occurs. At the completion of the test, the gears are removed from the fixture, cleaned as before, and reweighed to    determine weight loss. The wear rate in mg for 10,000 cycles is then calculated permitting a comparison of different lubricants. New  test  gears  are  used  for  each  run even  though  there  is  virtually  no wear  of the  steel  gear  as  compared  to the  brass  gear.

Both fluid products and lubricating greases can be tested as gear lubricants on this apparatus. Indications  are  that  with  increase  in viscosity  of  gear  oils  the  gear wear   decreases. No  speculations are  given  as to how  much  of    the  wear  might  be  due  to abrasion which  is due  to particles  from  the gears.

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.