The present disclosure relates to a tandem walking beam suspension system which comprises a main walking beam pivotably mounted to the vehicle sub-frame, a first pair of spaced apart and parallel secondary walking beams pivotably mounted about the main walking beam first end, a second pair of spaced apart and parallel secondary walking beams pivotably mounted about the main walking beam second end, a first pair of rollers rotatably mounted in-between and to the first pair of secondary walking beams, and a second pair of rollers rotatably mounted in-between and to the second pair of secondary walking beams, the first and second pairs of rollers being configured to roll along the track when the track-mounted vehicle is in displacement. The system may further comprise a compression device connecting the sub-frame and the main walking beam such as to provide vertical displacement of the main walking beam relatively to the sub-frame.