Leakage of Gear Oil onto Brakes

The most common reason for leakage of oil from differential gear cases onto brakes is overfilling of the housing. Under such conditions, the leakage will probably take place no matter how effective packing may be. Use of quite low viscosity gear lubricants, for example, SAE 75 grade in hot weather may also contribute to such leakage. Use of air pressure to help remove oil from the gear box may also cause leakage onto brakes. Failure of packing should also be investigated case there is a problem of gear lubricant on brakes.

Demulsibility of gear oils

Lubricating oils vary in their tendency to emulsify with water; therefore, if emulsification of gear oils is likely to be a problem, the base oil should be investigated. Any polar compounds remaining in the oil after refining, such as sulfonates, petroleum acids, and even asphaltic bodies, may help to stabilize emulsions. Well refined oils of low viscosity  will  have  the  least  tendency  to  from  permanent  emulsions  with  water.

High interfacial tension will tend to cause emulsions to break. Many oil field emulsions are broken by causing the emulsion to revert from water in oil type to oil in water type. However, the best solution for this type of trouble is to choose oil additive combinations which do not promote emulsification.