Motors and Drives
Bolts with waisted shanks put rail company back on track
T
he 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, M12x140. Due to the load that was applied
transverse to the bolt axis the bolts became instable after a short time in use. They were applied in the wheel drive system. After analysing the reasons for the
problem, SBB and Bossard AG worked to develop a stable bolted connection that also increased functional safety. Finally, the
solution was the use of a bolt with waisted shank. This solution has lots of advantages, including low level of loss in tightening force when setting up the connection. That leads to considerable security against it coming unscrewed by itself. Optimised mating surfaces mean that
the torsional or transverse stresses in the waisted shank can be eliminated. And the durability is substantially greater than for conventional standard bolts, even under a
vibrating load. l Enter 62 or ✔ at
www.engineerlive.com/ede
Bossard AG is based in Zug Switzerland.
www.bossard.com
Heavy-duty range for ball screw drives
L
inear motion specialist Kammerer introduces its extended product range of large-ball screw drives. The new ball screw drives are designed to support heavy
loads despite long traverse distances. The advantages of the new large-ball heavy-duty series are
their higher load capacities – which are reached at the DIN- standard nominal spindle diameter – and the low number of ball rotations per spindle revolution, which extends the ball screw drives’ service life. This series also features newly developed deflection elements with optimised ball track. With its new heavy-duty range, Kammerer now offers ball
screw drives with nominal diameters of up to 160mm and lengths of up to 15m. Depending on the required load rating and pitch, the screw
drives contain balls of sizes 9.52mm, 12.7 mm, 15.0mm and 20.0mm. l
For more information,
www.kammerer-gewinde.com Circle 63A or ✔ at
www.engineerlive.com/ede
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