Ursus Bison

Additional Notes

• The Ursus Bison manual transaxle capacities span a wide range across the lineup, from 25 liters on the Bison 60-35 2WD up to 50 liters on the three largest variants. Capacities of this scale are characteristic of integrated transaxle assemblies in agricultural tractors, where the transmission, differential, and rear axle housings share a common fluid reservoir rather than using separate, smaller sumps.
• The Bison 60-35 2WD carries a 25-liter transaxle capacity, which is notably half that of the Bison 105-65 and 85-50 models. The smaller capacity aligns with the 60-35 being the lightest and lowest-powered variant in the range, with a correspondingly smaller drivetrain housing volume.
• The Bison 105-65 and 85-50 both share a 45-liter transaxle capacity despite differing in power output. Shared capacities across different power ratings can reflect the use of a common transaxle housing design scaled to a particular chassis class rather than strictly to engine output.
• The Bison 120-85, 145-100, and 160-110 all specify a 50-liter transaxle capacity. At 50 liters, the fluid volume is substantial enough that even minor contamination or degradation can have a significant effect on lubrication quality across the entire drivetrain, making the defined service intervals particularly relevant.
• A 100-hour check interval applies across all six configurations. In agricultural equipment, hour-based intervals are used instead of mileage because tractors accumulate operating time under varying load conditions, and engine hours provide a more consistent measure of mechanical wear and fluid stress than distance traveled.
• The fluid change interval for five of the six configurations is set at 800 hours or 12 months, whichever comes first. The dual-trigger format means that even a tractor with low annual operating hours would still require a fluid change within a calendar year under normal use conditions.
• The Bison 145-100 specifies a change interval of 800 hours without the accompanying 12-month calendar trigger listed for the other variants. Under the 800-hour-only specification, the change interval is governed solely by accumulated operating time rather than a combined time-and-calendar schedule.
• All six configurations are designated for normal use conditions. In service interval terminology, a normal use designation typically reflects standard operating environments, as opposed to severe conditions such as continuous heavy loading, extreme temperatures, or frequent short-cycle operation, which would generally call for shortened intervals.
• Both 2WD and 4WD drivetrain configurations are covered within the same capacity and interval specifications for the 105-65, 120-85, 145-100, 160-110, and 85-50 variants. Listing both drive configurations under a single set of figures indicates the transaxle fluid system is common to both variants within each model designation.