Steering gears

The task of steering gears is to transfer the rotational movement of the steering wheel to the front wheels of the vehicle via the tie rods. Depending on the design, this occurs directly or indirectly via a rack. There are also many solutions in this area that thyssenkrupp offers its partners in the automotive industry.

HPS

HPS systems are powered hydraulically. These rack power steering systems can be used in all vehicle classes because they meet all of the requirements for safety and driving comfort – in compact cars as well as luxury sedans.

Characteristics:

  • Wide scope of application across all vehicle classes
  • High degree of safety
  • Speed-dependent steering assistance

Rack EPS

In contrast to HPS, Rack EPS is powered electrically. With these steering gears, the assist torque acts directly on the rack. At thyssenkrupp, we align the servomotor and the control unit parallel to the rack. The torque of our own electric motor is transferred to a ball screw via a toothed belt. The ball screw then moves the steering rack which, in turn, moves the vehicle wheels to the turning angle.

Characteristics:

  • Rack forces up to 18 kN (small utility vehicles)
  • Speed-dependent steering assistance
  • Improved steering feel due to “column torque control”
  • Interface for vehicle assistance functions (steering torque and angle)
  • Modular design for higher volume
  • Good road feedback due to low system friction and low inertia
  • Simplified vehicle coordination in comparison with hydraulic systems
  • Low stress on the steering train because the assist torque acts directly on the rack
  • Low noise emissions because the servo unit is installed in the engine compartment
  • No additional space needed in the cockpit

Dual pinion EPS

Dual pinion EPS is also an electrically powered steering gear. It is used in vehicles from the middle to upper middle classes as well as in small SUVs, providing up to 13 kN rack force. In this EPS system, the engine can also be aligned parallel to the steering system. The assist torque of the electric motor is transferred to the rack via a second drive pinion.

Characteristics:

  • Engine can be aligned parallel to the steering rack
  • Torque transfer via a second drive pinion
  • Greater flexibility in installation space design
  • Lower costs than for Rack EPS