Malfunctioning of Other Mechanical Elements

Misalignment may be due to wear of bearings and in extreme cases of failures it may be difficult to determine whether a bearing or a gear failed first. In case of bearing failures, when lubrication was at fault, either oil did not get to the bearing. Or the proper oil was not used. Where  a common  oil is used for bearings and gearing, the  viscosity of the oil is  generally  a compromise  since  the bearings operate best with  a lower  viscosity oil than  is dictated for the gear sets. Therefore, when bearing trouble is encountered, thought might be given to use of a somewhat lower viscosity lubricant.

Malfunctioning of flexible couplings may also contribute to trouble with gear sets. Such couplings are often used to connect reduction gears with a different piece of apparatus. These  couplings may not only  break but  also  become  jammed, so that  they  are no longer flexible; thus the  gear  shaft will  be thrown out of line. Another possible source of trouble might be a break in a gear case or supports which would permit a shaft carrying gears to be misaligned.

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.

Desirable characteristics in gear and transmission lubricants

A number of characteristics, which were not evident in the discussion of functions of gear lubricants, contribute to satisfactory application of such products. After listing some of these qualities, consideration will be given as to what contributes to such characteristics. Such qualities include:

(a)    Adhesion

(b)   Compatibility

(c)    Freedomfrom separation

(d)   Minimumaction on other components of mechanisms, as seals, etc

(e)   Oiliness

(f)     Oxidation  stability

(g)    Satisfactory demulsibility

(h)   Satisfactory detergency

(i)    Satisfactory foam inhibition

(j)    Satisfactory viscosity temperature characteristics

(k)      Shear stability

(l)   Reasonable cost.