<p>The rack railway is widely used in mountainous scenic areas with complex vibration environments owing to its excellent adaptability to large-slope lines. Stable current collection from the collector shoe and third rail system (shoe-rail system) is essential for the proper operation of the rack vehicle, and this stability can be influenced by gear-rack engagement. Taking into account track irregularities, nonlinear wheel-rail contact, time-varying mesh stiffness of the gear-rack, and shoe-rail interaction, a rack vehicle-track spatially coupled dynamics model which is validated by field-tested results has been developed to analyze the vibration characteristics of the shoe-rail system on large-slope line. Furthermore, the effect laws of the running speed and third rail joint gaps on the dynamic performances of the shoe-rail system are studied. The results indicate that the vibration of the collector shoe on the rack bogie is considerably influenced by gear-rack mesh excitation, particularly in the longitudinal direction. Owing to the damping effects of intermediate components such as the tension spring, the bogie frame is less affected by the excitation originating from the shoe-rail contact zone. Increased operational speed intensifies the vibrations of the collector shoe, thereby diminishing current collection performance. Furthermore, an off-line state of the system may occur as the collector shoe passes over third rail joint gaps, which negatively impacts the current collection. This study provides a theoretical basis for the engineering design and performance enhancement of the current collection system in the rack railway.</p>