Drive shaft, also known as semi shaft or constant velocity universal joint assembly. The drive shaft is a solid shaft that transmits torque between the differential and the drive wheels. Its inner end is generally connected to the drive shaft gear through a spline, and its outer end is connected to the wheel hub.

 

A drive shaft is installed between the differential or end reducer gear and the wheels, consisting of two or one set of constant velocity universal joints, an intermediate shaft (core shaft), and other parts, which transmit the power of the engine to the wheels and drive the car.

 

Types of Drive Shafts:

• Fully floating drive shaft
• 3/4 floating drive shaft
• Semi-floating drive shaft

Fully floating drive shaft:

When working, it only bears torque, and the two ends do not bear any force or bending moment. In layman’s terms, it only bears the torque from the engine, and the load torque of the vehicle is all borne by the axle.

The outer end flange of the fully floating drive shaft is fastened to the wheel hub with bolts, and the wheel hub is mounted on the axle sleeve through two bearings far apart. Because of its reliable operation, it is widely used in commercial vehicles.

 

3/4 floating drive shaft:

 

In addition to bearing all torque, it also bears part of the bending moment. Its most prominent structural feature is that only one bearing is designed at the outer end of the axle, and the bearing supports the wheel hub. In addition to bearing torque, this axle also bears the bending moment caused by the vertical force, driving force and lateral force between the wheel and the road surface.

Due to the poor support stiffness of one bearing, 3/4 floating drive shaft is rarely used in automobiles, and is generally only used in passenger cars and vehicles with a small total mass.

 

Semi-floating drive shaft:

The supporting bearing of the semi-floating drive shaft is located in the inner hole of the outer end of the axle sleeve. The wheel is mounted on the axle. In addition to transmitting torque, its outer end also bears all the forces and moments caused by the reaction force of the road surface on the wheel.

The semi-floating drive shaft is used in passenger cars and some commercial vehicles because of its simple structure, small mass and large load.

Reference：Wikipedia – Drive Shaft Overview