Falex Four-Ball Extreme Pressure Test Machine

The Four-Ball EP Test measures a lubricant’s extreme pressure properties under High Hertzian contact in pure sliding, or pure rolling, motion. The test is used to determine the load carrying properties of a lubricant at high test loads.

Three determinations are made:

• Load-Wear Index (LWI)


• Last Non-Seizure Load (LNSL)


• Weld Point (WP)

The Falex Four-Ball EP Test rotates a ½-inch diameter ball in contact with three similar balls held stationary in the test cup. The contact surfaces are covered with test lubricant, a load is applied and a timed test is performed. Normally, the wear scars on the three lower balls are measured and averaged. The test is generally terminated at the load where the rotating ball ‘welds’ to the three stationary balls.

Test Methods:

ASTM D2596, ASTM D2783, ASTM D2266, ASTM D4172, CEC L-45-A-99, IP 239, IP 300, IP 300 (obsolete), DIN 51350-1, DIN 51350-2, DIN 51350-4, DIN 51350-6