Effect of Temperature on Synchronizer Ring Performance

Abstract

The brass synchronizers are not resistant to abusive conditions of gearbox operations, but they are very durable and cheap when used on their favorable material property working limit. The main failure which can occur in the gearbox due to the synchronizer is crash noise. During gear shifting the gear crash will create high discomfort for the driver and must apply high force to change the gears. The main factors which contribute to the crash phenomenon are the insufficient coefficient of friction, high drag in the system, and high wear rate of the synchronizer rings before the intended design life of the synchronizer.

The brass synchronizers were tested on the SSP-180, ZF synchronizer test rig to know the effect of the synchronizer performance parameters like the coefficient of friction, sleeve force, slipping time as well as durability parameters like wear rate when the operating temperature of the oil is changed. This study will help to predict the impulse behavior, surface pressure, and power of the brass material and oil for enhancing the endurance life of the synchronizer.

The effect of gearbox oil drag induced on the synchronizer system in different temperature conditions is also studied in this research work. This helps to reduce the contribution of the drivetrain losses of the gearbox, and it will also give the better shift quality. The wear rate analysis makes it possible to predict the warranty life of the gearbox in the design phase itself. In the case of shift quality, it was identified that the presence of the drag is creating the speed difference between the gear and synchronizer hub. This is creating a gear clash noise when shifted at a slow speed. The data was captured at low temperatures and high temperatures. It was found that the increase in the temperature helps in reducing the drag locally which allows smoother gear shift without speed difference.