All greases have high pressure performance, and greases with extreme pressure additives generally have good extreme pressure performance. Those greases cannot be said to have extreme pressure performance.
Generally speaking, the higher the PB value, the higher the load resistance, that is, the better the extreme pressure performance, according to GB/T7323-2008 & LT;
Extreme pressure Lithium-based lubricating ester & GT;
The standard requirement is not less than 588N to detect PB value according to the four-ball method.
Methods the profile
Three steel balls of 12.7mm diameter are clamped in an oil box and covered by the tested oil. Another steel ball of the same diameter is placed on top of the three balls and subjected to a force of 147N(Qiaodi) or 392N(40kgf), which becomes a "three-point contact".
After the oil test reaches a certain temperature (75℃ ± 20C), the top ball rotates at a certain speed for 60min, and the wear resistance of the oil test is evaluated by the mean value of the spot diameters of the following three balls.
SH120 automatic four-ball machine grease extreme pressure performance test is in the form of sliding friction, under the condition of extremely high point contact pressure, mainly used to evaluate the bearing capacity of lubricant.
There are three indexes, including the maximum clamping load Pb, sintering load Pd, and comprehensive wear value ZMZ, etc. In practical application, different evaluation indexes can be selected according to different uses of lubricants.
The four-ball friction testing machine can also do the long time anti-wear test of lubricant, measure the friction coefficient, and record the friction force and temperature curve.
Equipped with a special spot measuring system, it can realize the calculation screen display, measurement and recording of friction pairs.
Special accessories can also be used to perform the end face
Simulation test of friction damage and material.
The design principle of the machine draws on the loading stability of the lever four-ball machine and combines with the loading characteristics of the servo valve, and realizes automatic zero clearing and self clearing through servo motor, air spring and closed-loop control software
Dynamic loading, automatic holding, automatic testing, automatic unloading, automatic measurement of the diameter of the grinding spot and taking pictures, one-key operation
Yes, data storage one-button storage test speed, error is very small, good repeatability, no pollution, no noise, high efficiency.
Determination of extreme pressure properties of lubricants by the four-ball machine method;
Gb3142-82, determination of bearing capacity of lubricant (four-ball method);
SH/T0189-92, determination of wear resistance of lubricating oil (four-ball machine method);
SH/T0202-92, Determination of extreme pressure properties of grease (four-ball machine method);
Determination of wear resistance of lubricating greases, SH/T0204-92 - Four-ball machine method.
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