Emerson VSG Manual page 55

Service
A. The Nord-Lock lock washer sets are used in many
®
areas in both the VSG & VSSG screw compressors that
require a vibration proof lock washer.
B. The lock washer set is assembled so the course
serrations that resemble ramps are mated together.
C. Once the lock washer set is tightened down, it
takes more force to loosen the bolt that it did to
tighten it. This is caused by the washers riding up
the opposing ramps.
55