Ashless Antiwear and Extreme-Pressure Additives 241
for oils. These procedures involve the running of a series of 10 s tests over a range of
increasing loads until welding occurs. From the scar measurements, the mean load (load-
wear index) is calculated and it serves as an indicator of the load-carrying properties of the
oil being tested.- FZG Four-Square Gear Test Rig. The FZG test equipment consists of two gear sets,
arranged in a four-square confi guration, driven by an electric motor. The test gear set is
run in the test fl uid, while increasing load stages (from 1 to 13) until failure. Each load
stage is run for a 15 min period at a fi xed speed. Two methods are used for determining
the damage load stage. The visual rating method defi nes the damage load stage as the
stage at which more than 20% of the load-carrying fl ank area of the pinion is damaged by
scratches or scuffi ng. The weight loss method defi nes the damage load stage as the stage at
which the combined weight loss of the drive wheel and pinion exceeds the average of the
weight changes in the previous load stages by more than 10 mg. The test is used in develop-
ing industrial gear lubricants, ATFs, and hydraulic fl uids to meet various manufacturers’
specifi cations. - Falex EP/Wear Tester. The Falex test machine provides a rapid method of measuring the
load-carrying capacity and the wear properties of lubricants. The test consists of rotating a
test pin between two loaded journals (V-blocks) immersed in the lubricant sample. There
are two common tests run in this machine: one is an EP test (subjecting a test lubricant to
increasing loads until a failure occurs) and the other is a wear test (subjecting a lubricant
to a constant load for a defi nite period of time while measuring the wear pattern). - Timken EP Test. This test provides a rapid method of measuring abrasion resistance and
the load-carrying capacity of lubricants. A number of lubricant specifi cations require
Timken “OK” loads above certain minimum values. The mode of operation consists of
rotating a Timken tapered roller bearing cup against a stationary, hardened steel block.
Fixed weights force the block into contact with the rotating cup through a lever system.
The OK load is the highest load the cup and block can carry without scoring during a
10 min run. Timken abrasion tests are run under fi xed loads for extended time periods,
and the weight loss of the cup and block are a measure of the abrasion resistance of the
lubricant. - L-37 High Torque Test. The CRC L-37 test operates under low-speed, high-torque condi-
tions. It evaluates the load-carrying ability, wear stability, and corrosion characteristics
of gear lubricants. The test differential is a Dana Model unit driven by a Chevrolet truck
engine and four-speed transmission. A complete, new axle assembly is used for each test
after a careful examination of gear tooth and bearing tolerance. After break-in at reduced
load and high speed, the test continues for 24 h under low-speed (80 axle rpm) and high-
torque conditions. - L-42 High Speed Shock Test. The CRC L-42 test is established to evaluate the antiscore
performance of EP additives in gear lubricants under high-speed, shock load conditions.
The test axle is a Dana Model unit driven by a Chevrolet engine through a four-speed truck
transmission. The procedure requires fi ve accelerations in fourth gear with inertia loading
and 10 accelerations in third gear with dynamometer loading. The lubricant evaluation is
based on the amount of scoring, and test results are expressed as percent tooth contact area
scored. - FAG FE-8 Test. FAG developed this test frame to be a fl exible tribological system to
conduct tests over a wide range of operating conditions with different test bearings. Short-
duration standardized tests have been developed for different applications. FAG also uses
longer-term testing (e.g., fatigue) for comprehensive evaluations. The FE-8 gear oil test
was developed specifi cally to evaluate the effectiveness of antiwear additives. The test
runs under heavy load and low speed that forces the bearing to operate under boundary
lubrication conditions.