Carriage with parallel sliding arms

In this track variation system, as in the previous type of undercarriages, the movement made by the boxes is a simple translation. The undercarriages with track variation by parallel sliding arms are characterised by two pairs of sliding seats. These pairs are offset one to the other and are differentiated for every side. Similarly, the extraction arms, having the same dimensions both on the right and on the left, are welded to the boxes so as to get two distinct and not coinciding axes. Due to the distinction among the axes where the stresses are applied to, the use of a system with parallel sliding arms generates more asymmetry than in case of an undercarriage with telescopic sliding arms. Additionally, here we have an increase in the frame length, due to the requirement of placing the sliding seats side by side. The use of undercarriages with parallel sliding arms allows for a remarkable reduction of the play and for a barycentre lowering, thanks to the undercarriage smaller height. These characteristics make these undercarriages suitable to be paired to machines such as cranes, that undergo the dynamic stress of the wind.