Performance evaluation of high-contact-ratio gearing for combat tracked vehicles - A case study

To enhance the mobility of combat tracked vehicles, a high-powered compact power pack is crucial. To achieve this goal, it is planned to apply the concept of high-contact-ratio (HCR) gearing to an independent final-drive planetary gear assembly of the tracked vehicle transmission. Before applying the concept to the final-drive, the performances of both normal-contact-ratio (NCR) and HCR conventional parallel shaft spur gearing systems are evaluated and compared. The results show that, for the same torque, HCR gears are subjected to lower loads and endure almost double the life of NCR gears. This reveals that an HCR gear can transmit more power for the same size. Furthermore, the power loss, vibration, and noise level of the HCR gearing are significantly lower than those of the NCR gearing. The proven results of the case study have encouraged the replacement of the existing NCR gearing with the HCR gearing for the final-drive planetary assembly of the combat tracked vehicle for evaluation.