Rubber Swell due to Gear oils

Where gear  oils  are  in  contact  with  rubber gaskets, seals, etc., the  action of  the  fluid on the  rubber compositions is of  importance. Consequently a Federal Test Method, 3604-T, has been set up. Such a test  can  be  varied as to  temperature, time and the  polymer     composition tested  depending upon  the    actual  service conditions of the  gear oil.

Thus, for ATF the following procedure is used. Sections of piston seals made from Acadia 3612 rubber compound are subjected to hot transmission fluid. Measurements of volume and hardness are made before and after the test. Two  seals are  cut  into  eight  sections each  and  the  sections  are  suspended  in  test  tubes  containing the lubricant and  held in a bath  at  300 degree F for  70  hours. The  sections are  then  cooled for  thirty  minutes  to  one hour in a  fresh  portion of the  test  fluid maintained at room  temperature. After wiping dry, the final volume and durometer readings are taken.

Gas, Fluid, or Solid Lubricants and Their Future

Thought is being given to experiments and   perhaps usage of gear lubricants in each of the above states. Application will be found  for   both  gases  and  solids as gear lubricants, the  major  portion of operating  gears  in  the  future  will  continue to be lubricated with fluids.

Naturally these fluids will be improved for many applications. For such purpose, the first thought concerns synthetics. However, the abundance and relative cheapness of petroleum oils rules out synthetics for most application in the immediate future. It can  be expected  that  mineral  oils will continue to be  upgraded  by  greater  selectivity , more  chemical  processing, and use  of  improved additives.