“We help people on the road stay safe.”
Julie, Senior Product Engineer, Michigan
As a link between the road and the vehicle, the wheel suspension joints ensure an accurate wheel guidance and easy steerability. LEMFÖRDER suspension joints boast an excellent responsiveness thanks to low torques, display extremely low elasticities, and therefore permit precise and safe driving maneuvers.
The most important wheel suspension designs include (wheel) suspension ball joints, supporting joints, and cross-axis joints. These ball joints are entrusted with the task of connecting the wheel suspension control arms with the wheel carrier and, consequently, with the wheel.
While the suspension ball joint usually only transfers longitudinal and lateral forces with a low amount of vertical forces, the vehicle weight is also supported via the supporting joint (axial spring and damper forces).
The (wheel) suspension ball joint is entrusted with the task of establishing the connection and, consequently, the support between the front axle control arms and the axle body/ carrier (steering knuckle). Its task is to guide the wheel carrier and wheel, to enable the spring deflection of the wheel, and to permit the steering movement on the front axle. It is always installed at the triangle apex of the control arm. The height fixation is performed via the ball stud. The ball joint should be easy to move, low in flexibility, maintenance-free, and noise-insulating. These four, partly contradicting requirements are met at LEMFÖRDER, e.g. thanks to premium plastic shells in the joint.
In terms of design, the suspension ball joints and the supporting joints are only marginally different from one another. The supporting joint is located on the opposite side to the suspension ball joint, assembled in the steering knuckle. It assumes forces in all directions and can be installed in a suspended or vertical manner. The ball joint housing is usually attached in the control arm and the ball stud is usually attached in the steering knuckle via its conical taper or a cylindrical dog point. Advantage: This mounting is maintenance-free.
Cross-axis joints are primarily installed on the rear axle. They consist of a ball with cylindrical taper on both sides and a continuous bore in the middle. Although they are similar to the ball joint in terms of function and structure, their anchorage corresponds to that of rubber bearings. In contrast to rubber bearings, cross-axis joints are able to transfer extremely high dynamic forces and have no aligning torque. Cross-axis joints are preferably used if a stiff control arm connection is desired – on sports cars or light commercial vehicles for instance.
What she does at ZF:
How can curtain airbags – installed in the headliner above the front windshield – expand faster, without fail and cover a larger area? And how should the airbags be designed? These are just a few of the questions that Julie seeks to answer everyday in her role as product engineer at ZF Michigan. She works in the Occupant Safety Systems Business Unit, which designs and produces passive safety systems such as airbags and seat belts. She is responsible for designing curtain airbags for various automobile models from General Motors.
How she came to ZF:
Cars are her hobby, her passion. Throughout her 20-year career, Julie has never done anything else. While completing her degree in mechanical engineering at Oakland University, she worked part-time for Chrysler. After graduating, she switched over to the automotive supplier sector and ultimately found her way to ZF three years ago. A move that she has never regretted: “I originally chose ZF because it was near where I lived. Three years later, I can honestly say that I’m excited about the technologies that we develop and manufacture, not to mention the great people I work with.” She particularly appreciates the diversity of the products and how practical they are for every day use.