Daniel Häggström

Robust pre-synchronization in heavy truck transmissions

Transmission performance directly influences vehicle behaviour, energy efficiency, and perceived quality. A modern transmission is an aggregate of interacting sub-systems, e. g. gears, bearings, sy ...

A Verified and Validated Model for Simulation-Driven Design of Heavy Duty Truck Synchronizers

The strong market trend toward lower fuel consumption for heavy road transports requires more frequent gear shifting and increased gear shift performance, i.e. shorter shift time. Increased shift p ...

Evaluation of synchronizer loading parameters and their ability to predict failure

Molybdenum coated gearbox synchronizers are tested in a μ-comp test rig under varying loading conditions until failure. Four different parameters used to describe the thermomechanical load are evaluated just before failure to compare their ability to predict failure. The parameters evaluated are the synchronized kinetic energy, the synchronization power, and the focal as well as the average surface temperature increase. The focal surface temperature increase as well as the average surface temperature increase is found to predict failure with relatively good accuracy. It is shown that there exists a threshold which divides the synchronizer into either a very long or a very short service life. Additionally, a method to determine the average surface temperature in the gearbox management system is proposed.