Abstract
So-called "thrust cones" are currently being used in highspeed, single helical spur gear drives for taking up axial forces. To date, thrust cone technology has not been used in vehicle transmissions. To reduce noise emissions in heavy commercial vehicles, the planetary gear set had to be changed from straight to helical-cut gearing. Both single and double acting thrust cones have been developed to take up axial forces in the available installation space. Due to the special conditions, vehicle transmission applications differ greatly from those for stationary transmissions. While stationary transmission thrust cones in the EHD range must only run free of wear, in vehicle transmissions, it is also important to take into account the additional factors of fatigue lifetime, scuffing resistance and risk of wear. The thrust cone performance limits were determined under near-series conditions on a specially-designed gear load test bench. Suitable calculations procedures were then developed. From specification to production, the total development stage was approx. 2 years. Helical-cut planetary gear sets using thrust cone technology have been used as standard since mid 1996 and have proven to be very effective. A noise reduction of approx. 10 to 15dB has been achieved by changing from straight to helical-cut gearing.
