Steering Linkage Induced Vehicle Pull during Straight Line Braking 2012-01-1916

The vehicle pull (sideways) is a complex outcome of many parameters in an automobile vehicle. This is mainly due to steering, suspension, brake, wheels and chassis parameters. The road conditions like road camber also plays an important role in vehicle pull behavior. All efforts are put in design and manufacturing processes to maintain controlled vehicle pull in normal driving condition. Even though normal vehicle pull seems to be in acceptance limit (subjectively), its intensity increases many folds at the time of harsh braking. In these kind of panic situations where driver firmly holds on the steering wheel, it is expected that the vehicle should stop without deviating too much sideways from its intended straight line path to avoid any kinds of accidents.

This work is an outcome of systematic study carried out to understand the root cause of brake pull as a field complaint on current production vehicles and adopting best possible solutions to minimize the brake pull. This paper presents an experimental study and comparison of contribution of two basic kinds of steering linkage layouts type 1 and type 2 (detailed descriptions followed in section 1) on RHD (right hand drive) vehicle, used in front-wheel-steered vehicles having independent suspension on vehicle pull and brake pull. Brainstorming resulted in some critical hypothesis about possible contribution of these two basic layouts on vehicle pull while braking which was further supported by primary CAE (computer-aided engineering) analysis using classical approach (ADAMS® Model). Same has been validated through experimental tests also. While both of these mechanisms are widely used by different automobile OEM's (original equipment manufacturers) as they fulfill most of the design requirements of steering systems, the in-depth analysis of contribution of these two layouts on brake pull surely puts one on top of the other. The work helps in understanding the finer details of steering linkage design requirements and provides design guidelines to deliver better product through improved safety and better customer satisfaction.