What causes "dog tracking" in a tandem axle tractor?

Dog tracking in a tandem axle tractor refers to a condition where the rear axles do not track inline with the front axle, causing the vehicle to appear to move sideways while driving. This misalignment can lead to uneven tire wear and handling issues.

Worn walking beam bushings can lead to a misalignment of the axles. The walking beam is a critical component in the suspension system that connects the two axles and allows them to move independently while maintaining the proper alignment. When the bushings that allow for this movement become worn, they fail to maintain the correct geometric relationship between the axles. As a result, the rear axles may not align properly with the front axle, causing the dog tracking phenomenon.

Other factors such as broken shock mounts, worn torque rod bushings, or incorrect suspension height can also affect vehicle dynamics, but they do not specifically address the misalignment caused by the walking beam bushings. The primary issue with worn bushings in the walking beam is that it directly impacts the ability of the rear axles to stay aligned with the front, which is the root cause of dog tracking in this scenario.