is the test used in developing industrial gear
lubricants to meet equipment manufacturers’ specifications. The FZG test
equipment consists of two gear sets, arranged in a four-square
configuration, driven by an electric motor. The test gear set is run in the
lubricant at gradually increased load stages until failure, which is the
point at which a 10 milligram weight loss by the gear set is recorded. Also
called Niemann four-square gear oil test.