lic system and this is why gear oil SAE 90 or SAE 140 are not suitable for tractor transmissions. They are too heavy for the hydraulic pump and one will notice slow hydraulic response particularly in the morning when it is
cold. Another
function of tractor hydraulic & transmis- sion oil is to lubricate the tractor brakes which are immersed in the oil. The oil should stop brakes from making squawk- ing noise. Therefore, the oil used for the brakes must have anti-squawk proper- ties which automotive gear oil SAE 90 or SAE 140 do not have. A good tractor hy- draulic & transmission oil must have an- ti-squawk properties. Another problem of SAE 90 and SAE 140 is that they accumu- late water from the atmosphere resulting in rusting of gears and bearings. Another common mistake is the use of engine oil in the hydraulic & transmis- sion system. Engine oil does not have Ex- treme Pressure(EP) properties required to protect the wearing-off of the gear teeth and other parts in the transmission. It also does not have anti-squawk proper- ties and therefore the wear of the brakes is accelerated. Also, the viscosity is high, thus promoting water accumulation and rusting.
The other inappropriate practice is to use normal hydraulic oil viscosity grade
68 in the hydraulic & transmission sys- tem. Although the viscosity is adequate for the hydraulic oil, the oil lacks wide temperature applicability that is re- quired in a proper tractor oil. It does not have extreme pressure properties; thus, it promotes rapid wear of the transmission system. Furthermore, it does not have an- ti-squawk properties required in the wet brake system. There are two types of tractor lubri- cation to choose from depending on the number of tractors and the recommen- dation the tractor manufacturer gives which are widely available on their web- site. The ideal oil for the tractor transmis-
sion is commonly referred to as Univer- sal Tractor Transmission Oil (UTTO) and it’s an SAE 10W30 which makes it light enough for the hydraulic system. It has EP properties to the level of GL-4 that makes it ideal for gears in the transmission sys- tem. It also has anti-squawk properties that reduce the noise and the wear of the wet brakes. The light viscosity makes it not trap water from the atmosphere and thus prevents rusting of the bearings and gears. The SAE 10W30 is a multigrade oil which makes it suitable for operations over a wide temperature range. This oil is generally not recommended for engine oil lubrication. The other tractor fluid is the super
Low grade greases may melt out of bearing at low temperatures. They also do not resist water wash-out and during the rainy season possibility of bearing failure increases.
tractor oil referred to as Super Tractor Oil (STOU). This oil can be used for both engines and transmissions and it comes in qualities of API CD, CF or CG-4. It is a SAE 20W40 and it is good for lubrication of engines. The drain interval adopted will depend on the API Specification and the operating environment. It is suitable for gear or transmission application as it has EP properties up-to API GL-4. It also has anti-squawk properties to suitably lubricate the brakes. The viscosity of SAE 20W40, although strongly high, is accept- able by most hydraulic pump manufac- turers.
Damaged tractor hydraulic pump. SOURCE | COURTESY March 2023 | LUBEZINE MAGAZINE 19
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