This type of lock is used just as the side lock, to prevent rotation of the piston ring in the groove. If this type of lock is not used, the lock ends of the piston ring can move to a flushing port due to a possible rotation. The preload of the piston ring allows the ends of the lock to protrude outwardly or within the flushing port.

Inside notch piston ring

This situation is very undesirable and can cause all kinds of problems such as a jammed piston. The ring is then jammed by this inside lock. The lock can be produced with either a radius or with bevelled edges depending on your specifications.

ISO 6621-4 designation = NH1 to NH3

Possible applications:
– Combustion engines (two-stroke)
– Gas engines
– Hydraulics
– Steam applications