Shift Force Loading Rules Research for Automated Mechanical Transmission

Li Bo, Ge Wenqing*, Zhao Yiqiang, Chen Shanshi
School of Transporation and Vehicle Engineering, Shandong University of Technology, Zibo 255049, China.

© 2015 Bo et al

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


To improve the system reliability and reduce the shift shock of Automated Mechanical Transmission, shift force loading rules is researched on the basis of strength and stiffness analyzing of shift fork. The shift mechanism of A-5- speed manual transmission is used as an example to illustrate the simulation, co-relation and validation of the shift fork strength and stiffness. The three-dimensional model of the shift fork is built and the finite element analysis model based on ABAQUS is established. And then, the influence of strength and stiffness of shift fork on the shift force loading rules can be analyzed. The fork tends to deflect with the synchronizer sleeve during synchronization thus acting as a damper and storing energy, the maximum instantaneous force output by driving device under the strength requirement of shift fork is determined. The shift control strategy is corrected according to the stiffness analysis of shift fork. The results shown that, in order to meet the strength requirement of shift fork, the maximum instantaneous force for the 4 gear fork is 1185.5N. In the same time, the maximum deformation on fork legs is 0.617 mm. The research provides a sufficient theoretical basis for formulating the shift control strategy.

Keywords: Maximum instantaneous force, shift force loading rules, shift fork, stiffness, strength.