Roberts Four-Bar Front Suspension for Straight Wheel Travel

The patent applies a Roberts parallelogram mechanism that dynamically adjusts the geometry of the four-bar linkage to transform the rotational motion of the wheel support into a rectilinear trajectory of the wheel axis. The mechanism uses equal-length cranks and a connecting rod arranged in a specific configuration that converts circular motion into straight-line motion, eliminating transverse sliding while maintaining the simplicity of revolute pairs.

The patent replaces the cylindrical pair mechanism (which provides straight-line motion but adds complexity) with a Roberts parallelogram mechanism using only revolute pairs. This substitution achieves the same rectilinear trajectory of the wheel axis through geometric constraints and kinematic relationships, eliminating the need for cylindrical pairs and their associated complexity while maintaining the benefits of simple hinge connections.