Transferability of the scuffing load capacity of gear oils determined on spur gears to hypoid gears: Classification of hypoid oils by use of a newly developed scuffing test method

The scuffing load carrying capacity is a decisive design criterion in the development of gears. In addition to the gear geometry, the entire tribological system of the gearbox must also be taken into account. Besides the loads and speeds occuring during the operation of the gears, the lubricant used and its additives have a significant influence on the scuffing load carrying capacity. In particular, hypoid gears show an unfavorable combination of high sliding velocities and high contact stresses in tooth contact with regard to the failure mode scuffing. To ensure safe operation, highly additivated gear oils are generally used in hypoid transmissions. Since it is generally not possible to determine the influence of the lubricant on the load carrying capacity of gears on the basis of physical or chemical oil data alone, experimental test methods are necessary. Due to the high scuffing load carrying capacity of highly additivated hypoid oils, the limits of many test methods are reached. In order to ensure testing highly additivated hypoid oils as close as possible to their application a new hypoid scuffing test was developed. However, since spur gear scuffing test methods can be carried out more quickly and with less resource and effort, the applicability of the spur gear scuffing test S-A10/16.6R/90 to high additivated hypoid oils is investigated. The comparability of the two test methods and the transferability of the scuffing load carrying capacity of a gear oil determined on spur gears to hypoid gears is evaluated in scope of this paper. © 2023 The Authors.