Abstract
Differential is used to decrease the speed and to provide moment increase for transmitting the movement coming
from the engine to the wheels by turning it according to the suitable angle in vehicles and to provide that inner and
outer wheels turn differently. Pinion gear and shaft at the entrance are manufactured as a single part whereas they
are in different forms according to automobile types.Mirror gear which will work with this gear should become familiar
before the assembly. In case of any breakdown, they should be changed as a pair. Generally, in these systems there are
wear damages in gears. The gear inspected in this study has damage as a form of shaft fracture.
In this study, failure analysis of the differential pinion shaft is carried out. Mechanical characteristics of the material
are obtained first. Then, the microstructure and chemical compositions are determined. Some fractographic studies are
carried out to asses the fatigue and fracture conditions.