What is the effect of caster angle on straight-line tracking?

Caster angle significantly affects straight-line tracking by influencing steering stability and returnability. Caster is the angle of the steering axis relative to the vertical axis when viewed from the side of the vehicle. Positive caster means the steering axis is tilted back towards the rear of the vehicle, while negative caster means it's tilted forward. Positive caster promotes straight-line stability by causing the wheels to naturally want to return to the center position after a turn. This is because the weight of the vehicle is effectively ahead of the steering axis, creating a self-centering effect. Insufficient or negative caster can lead to wandering, where the vehicle tends to drift from side to side, requiring constant steering corrections to maintain a straight course. Excessive positive caster can make the steering feel heavy and increase steering effort. The correct caster angle, as specified by the vehicle manufacturer, provides a balance between steering stability and ease of steering.