What is an Automotive Drive Shaft/Axle Shaft ?
The drive shaft/axle shaft transmits the drive force to the wheel. 1. Drive shaft (Independent suspension type) They must have a mechanism which absorbs changes in the length of the drive shafts accompanying the up and down movements of the wheels. In the case of FF vehicles, since the same wheels are used for steering and for driving, they must be capable of maintaining the same operating angle while the front wheels are being steered, and they must rotate the wheels at uniform speeds. 2. Axle shaft (Rigid suspension type) The right and left wheels are connected to the axle shaft. The axle housing supports the weight of the vehicle while also holding the differential in its center.
Construction and Operation
1. Constant velocity joints
The constant velocity joints prevent a rotation difference from occurring between the drive shaft and driven shaft no matter what the angle of the joint. These joints are mainly used in the drive shafts of vehicles with independent suspensions. There are various kinds of different types of constant velocity joints.
(1) Rzeppa (Birfield) joint The inner race fits into the bowl-shaped outer race, with six steel balls held by a ball cage between them. The construction of this system is simple and its transmission capacity is great. This type of joint is used on the drive shaft tire side.
(2) Principle of constant velocity joint (Rzeppa joint) A special curvature is provided on the ball seat in such a way that intersecting point (O) of the centerlines of the drive and driven shafts are always on the line connecting the center (P) of each steel ball. As a result, the angular velocity (speed of rotation through an angle) of the drive shaft is always identical to that of the driven shaft. (1/3)
2. Tripod joint In this joint,
there is a tripod with three trunnion shafts on the same plane. Three rollers are fitted on these trunnions, and fitted to each of the rollers are three tulips with grooves which are parallel to each other. The construction of this system is simple and it is inexpensive. Generally, this type of joint can move in the axial direction. This type of joint is used on the drive shaft differential side.
3. Double-offset constant velocity
The construction of this type of joint closely resembles that of the Rzeppa (Birfield) type, but it can slide in the axial direction. The outer and inner surfaces of the ball cage are offset axially from each other.
4. Cross-groove constant velocity
This is a small, light-weight joint in which the ball grooves of the outer race and those of the inner race are set at angles to each other. These are two types, one which slides axially, and one which dose not.
SERVICE HINT:
If there is a crack in dust boots of the constant velocity joint, the grease will deteriorate and flow out, which will cause abnormal sounds and make it impossible to drive. Since there are various types of boot clamps that hold the drive shaft boots, refer to the Repair Manual and handle them correctly. The type and amount of grease used inside the drive shaft boots varies depending on the model, so refer to the Repair Manual.
Drive Shaft Length
In the FF vehicles, differences in the length of the left and right drive shafts can also causes the steering wheel to jerk to one side or the vehicle to veer during quick starts or sudden acceleration. This phenomenon is known as “torque steer”. For this reason, some models use an intermediate shaft in combination with right and left drive shafts of the same length to prevent torque steer from occurring.
