Suspension joints

The most important designs include guiding suspension ball joints, supporting suspension ball joints and cross-axis joints.

The Lemförder Sensor Module is an innovation that provides information to the assistance systems in the car directly from the interior of the ball joint.

Function & Benefit

The wheel control or wheel suspension system joins the vehicle body to the wheel and its tire. The ball joints perform the task of connecting the control arms of the wheel suspension to the knuckle and thus to the wheel. The forces arising can be transmitted with the aid of the ball joints without restricting wheel mobility (compression and steering). As the connecting element between the road and vehicle, the wheel suspension (with the control arm and ball joint) provides for precise wheel control and for faultless, easy steering.

The ball joints must be designed so as to fulfill a multitude of partially conflicting requirements, such as a high load-bearing capacity, ease of handling, a small package, seal integrity/corrosion-resistance, light weight, and in some cases vibration damping.

Every ball joint (as applied in the steering knuckle) consists of a steel or aluminum housing and a steel ball stud. In addition there is a maintenance-free bearing with a plastic race and a lubricant to minimize wear and reduce friction. The bearing is protected from dirt and moisture by a rubber or elastomer sealing boot. The ball joint can rotate and tilt in every direction and thus has three degrees of freedom.

The two most important suspension joint designs (for steering knuckle application) are the supporting suspension ball joint and the guiding suspension ball joint.

A new development is the Lemförder Sensor Module (LSM). The sensor module captures data concerning the driving status directly in the ball joint. In addition to suspension joints, cross-axis joints are also used, predominantly for the rear axle.

Guiding suspension ball joint:
The guiding suspension joints are ball joints that primarily bear radial loads. They have the function of guiding the knuckle and wheel, allowing compression of the wheel and permitting steering movements of the front axle.

Supporting suspension ball joint:
In addition to transmitting radial guiding forces, supporting suspension ball joints also transmit axial elastic and damping forces. Since the sum of these forces is significantly greater than the radial forces alone, the supporting suspension ball joints are larger than the guiding suspension ball joints.

Cross-axis joint:
Cross-axis joints have a ball with cylindrical studs on both sides and a hole through the middle. Although the function and design of cross-axis joints are similar to those of ball joints, the type of mounting corresponds to that of rubber bushings. Cross-axis joints are used particularly when a very rigid connection of the control arms is desired, for example in sports cars where large angles arise (especially cardanic angles due to lateral tilting), and in SUVs or where it is necessary to bear high specific loads.

Advantages

Ball joint technology is employed wherever the joining of vehicle components must meet the most demanding requirements in terms of mobility and reliability. The technology directly affects driving safety, vehicle handling and comfort.