High-speed trains travelling at more than 400kph (250mph) will go into service on the Hamburg-Berlin route in 2002.
There is no wheel-to-rail contact on the Transrapid, which is propelled by magnetic induction. But the train is subject to high forces as it accelerates, decelerates and takes bends at high speed.
High dynamic loads and tension place huge stress on fastenings. Special washers were needed to prevent bolts becoming loose.
Vibration-proof, self-locking washers called NordLock were approved by German authority TUV after tests exceeding two million cycles.
The locking effect is based on a series of cams on one face of the washer, the angle of which is greater than the pitch of the bolt thread.
When two washers are installed, cam-face to cam-face and the bolt or nut tightened, the interfacing cams create a wedge which increases bolt tension and prevents vibration from loosening the fastener. Radial teeth on the reverse side of the washer provide extra security.
NordLock washers are available in the UK from Primatronic in Biggleswade.