Wheel Type Tractors and their Gear Lubrication

According to  Caterpillar, transmissions of a  few  models of wheel  type  tractors  require series  3 motor oils in an  SAE  30  grade above 32 degree F  and  in an  SAE  10W   grade  for  lower  starting  atmospheric  temperatures. The  transmission  lubricant  suggested  for  most  models of  wheel  type tractors  is a multipurpose type  gear oil conforming to MIL-L-2105. An  SAE 90  grade  is  recommended for  starting  temperatures above 32 degree F and  an  SAE 80  grade  for lower  temperatures. Below -10 degree F it may be necessary to dilute this latter grade with kerosene.

The  same MIL-L-2105 type of gear oil  and like  grades  are  suggested  for all models of wheel  tractor differential  and final  drive  compartments. It is recommended that transmission oil filters be changed every   250 hours, except in the case of three models where the period is 500 hours. The  suggested  oil  change  period  for both  transmission  and differential  and final drive  compartments  of wheel  type  tractors is 1000 hours.

 Similar tractors of other makes, as well as allied equipment, such as motor grades etc., will probably require similar types and grades of gear lubricants. However, it is better to follow instructions furnished by the equipment manufacturer or supplier.

Abrasive or cutting wear

Gear oils are not correctives for abrasive wear because here the action is due to hard particles between the gear face as they mesh. If the abrasive is due to loose metal, sand, etc; gear oils may wash the foreign particles from the moving areas, but unless the abrasives settle out they will continue to act as lapping compounds. However, if the viscosity of the gear oil is low, the large foreign particles may be deposited in areas where the velocity of the oil is low, and thus they will be harmless.

The best corrective for abrasive wear of gears is to drain and flush out the gear case and refill with clean oil. Circulating oil systems used for gear oils can be equipped with filters or strainers. Likewise, a settling period can be provided in the storage system for the fluid. Some gear cases in automotive  vehicles  have magnetized  drain plug  so that  most  iron or steel  particles will  become attached  as  the  gear oil  circulates. Where vehicles operate under conditions promoting  dust, as do many  tractors, it is wise to  drain  gear  cases  frequently  so  that  abrasives  filtering  into  the  gear  oil  will be removed.