Four-ball friction machines ЧМТ-1 and ЧМТ-1 (3) are meant for providing testing of liquid and semisolid lubricants, applied for lubricating of interacting surfaces, with the aim of defining the basic tribological characteristics of lubricating materials according to GOST 9490-75 “Lubricating materials, liquid and semisolid. Methods of defining tribological characteristics on a four-ball machine”.
Four-ball friction machines ЧМТ-1 and ЧМТ-1 (3) provide reproduction of normalized effects (axial load, fixed rotation speed etc.) to the testing samples, being in the tested lubricant, according to the requirements of the current normative technical documents for lubricating materials, for the further definition of the magnitude of wear of testing samples.
Location of machines ЧМТ-1 and ЧМТ-1 (3) by operation – on the floor of the room.
The operation mode of machines ЧМТ-1 and ЧМТ-1 (3) is cyclic. Testing time – 10 s or 60 min. The tests can be automatically stopped by the excess of the set value of the moment of friction of testing samples.
Power supply parameters:
– power supply of machines ЧМТ-1 and ЧМТ-1 (3) is made from the circuit of three-phase alternating current, with voltage of 380/220 V;
– fluctuation of the line voltage is from plus 10 up to minus 15 %;
– alternating current frequency – is (50 ± 1) Hz
- Operating principle of the machines is based on the reproduction of normalized effects to testing samples, being in the tested lubricant, with the further definition of the magnitude of wear of testing samples.
- As the testing samples the balls are used (12,70 ± 0,01) -10; 16 or 20 according to GOST 3722-81, made of steel ШХ-15 by GOST 801-78, which make a pyramid of four balls, contacting each other. The three lower balls are fixed stationary in the friction unit of the machine, in which the tested lubricant is placed. The upper ball, fixed in the machine spindle, is pressed to the lower balls with the preset force (axial load) and rotates with the fixed speed. The duration of tests is 10 s or 60 min depending on the chosen mode. By the appearance of the limit friction moment in the friction unit, equal to 1 180 N·cm (120 kgf·cm), the tests are stopped.
- The machines provide the creation of axial loads in the friction unit in the range from 59 up to 9 800 N [from 6 up to 1 000kgf]. The required value of axial loads is preset by installing the weight holder with the necessary set of weights in the position, defined by the index on a lever.
- The machines provide conducting the tests by the elevated temperature of a lubricant within the range from the air temperature up to plus 300 °С.
- The magnitude of wear of the testing samples is defined by means of measuring diameters of wear of each of the three lower balls with the help of a microscope with magnification not less than 24´, equipped with a reading scale with the division value of 0,01 mm and less.