The Unistress Piston Ring Expander was invented in 1948 by engineer Anders Østergaard, who was leader of the department for new constructions at B&W Diesel A/S for many years. The principle on which the Unistress Piston Ring Expander expands the piston ring to slip it over the piston, was patented in 1949.

To read more about the Unistress Piston Ring Expander, see products