Servotwin – latest generation of CV steering systems from Bosch
There is a long list of commercial vehicle assistance systems based on the connectivity of steering systems and on-board electronics: These include highway pilots, traffic-jam assistants, blind-spot assistants, automatic emergency braking on vulnerable road users, adaptive cruise control (ACC Stop & Go), lane-departure warning systems, turning assistants, maneuvering distance warning systems and many more.
To facilitate such features, an increasing number of commercial vehicles is equipped with Servotwin electrohydraulic steering systems.
Servotwin success – increasing numbers
The commercial vehicle manufacturers’ demand for these steering system is continuously growing. By now, several modern commercial vehicles are already equipped with electrohydraulic steering systems such as Bosch Servotwin. This number is expected to continue growing in future. For commercial- vehicle workshops, this means: Servotwin will be on the service schedules even more often in future.
Based on classic hydraulic steering systems
The electro-hydraulic Bosch Servotwin steering system basically consists of the RB-Servocom hydraulic ball-and-nut power steering system and a platform-based combination of an electric motor with control unit and a worm-gear transmission. The ball-and-nut power steering system – based on the principle employed in a classic hydraulic power steering system – provides most of the steering assistance. An oil circuit and a power cylinder provide the hydraulic steering assistance.
In addition, a turning motion of the steering wheel and the steering moment applied are detected by turning-angle and torque sensors and transmitted to the integrated electronic control unit. Taking other vehicle parameters into account – for instance, speed and load – it then determines the required additional steering moment. By means of an electric motor and a worm-gear transmission, the additional steering moment then acts on both of the input shafts of the RB-Servocom thus assisting the driver when steering.
By the connection of the steering system to the onboard electronics, Servotwin is not only suitable for its integration into comfort and driver- assistance features, but also into automatic driving functions.