The Swiss Federal Railways SBB was faced with challenges to stabilise its system of bolts that were causing high maintenance and downtime costs
Originally hexagonal bolts had been used – type DIN 931, 10.9, M12 x 140. The bolts were applied in the wheel drive system and due to the load that was applied, transverse to the bolt axis, the bolts became instable after a short time in use. Even though there was no security risk at any time, SBB was highly interested in finding an efficient solution.(…)
