When employees at the ZF plant in the Austrian town of Lebring watched the 100,000th AKC system roll off the line, there were no corks popping off champagne bottles. After all, this production line is located in a cleanroom and even the tiniest dust particles will trigger the alarm. Nevertheless, the cheers that erupted to celebrate this production milestone were heard loud and clear, and not only at the plant. Dr. Holger Klein, Executive Vice President of the Car Chassis Technology Division at ZF, sees this milestone as a huge success for several reasons: “First of all, it illustrates that the AKC enables almost any vehicle to easily benefit from active rear axle steering. Secondly, it has enabled ZF to cement its position as a market and technology leader in this product segment.” And last, but not least, this milestone highlights how the ZF production site in Lebring has so completely transformed itself in such a short period of time.” Located near Graz, it went from being an axle assembly plant to a hub for high-tech mechatronics. It is currently the company’s only AKC production site.
The 100,000 AKC systems produced to date are a mix of two different actuator configurations intended for different axle designs, with 60,000 central actuator systems and 40,000 dual-actuator systems having rolled off the line. The dual-actuator version celebrated its series premiere in 2013 when it went into volume production for rear axles in the Porsche 911 Turbo and 911 GT3 sports cars. This configuration features actuators which directly affect the right and left toe links. These actuators consist of control electronics, an electric motor, toothed belt drive and spindle mechanism. The Ferrari GTC4Lusso is also equipped with the dual-actuator configuration. The central actuator AKC design has one single, but somewhat larger actuator located in the center of the rear axle and increases the car’s overall performance. It is featured in other sleek speedsters, such as the Porsche Panamera. This central actuator AKC system also helps active rear steering in SUVs like the Audi Q7 and sedans like the BMW 7 Series and the Cadillac CT6. In the near future, this AKC system will appear in many more vehicles from a growing number of manufacturers, including pick-up trucks and compact cars. The versatility of these two designs means the AKC is compatible with any drive system on the market – from conventional internal combustion engines to hybrids and all-electric systems.
As soon as you look at the AKC benefits through a technological lens, the secret to the agility and stability of a vehicle equipped with this system will become immediately clear. When driving slowly, at a city speed limit, for example, the AKC steers the rear wheels in the opposite direction of the front wheels, endowing the vehicle with animal-like agility. Not only that, it feels like it can almost turn in place because the turning radius has been reduced by up to ten percent. At higher speeds, around 60 km/h, the system steers all wheels in the same direction. Even during high-speed steering maneuvers on the highway, its tracking stability remains supreme
Prime example of intelligent mechanical systems: ZF\'s active toe control kinematics AKC makes rear axles on passenger cars part of the steering system and serves all current and future megatrends in the automotive industry.
Yet another reason the AKC system is well on the road to success is because it can accommodate current and future megatrends in the automotive industry. For example, it increases safety because it reduces the vehicle’s tendency to break out in the rear. Also, it is more efficient because the system consumes power only on demand. Finally, the AKC also represents yet another building block in the world of automated driving because, if necessary, it can control a car in some situations without front-wheel steering. For all of these reasons, ZF has high sales expectations for this product. “In 2014, its first full production year, roughly 12,000 AKC systems rolled off our production lines. Today, that number has risen to a total of 100,000. In the coming years, we intend to increase production volumes to more than 250,000 units per year,” says Peter Buckermann, head of the Mechatronic Systems Product Line.