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The TE 96 is very simple “coast-down” tribometer using a miniature sliding four ball test configuration. The tester comprises a bench with a bell-jar vacuum chamber, which is connected to a vacuum pump. A motor driven vacuum feed-through provides a rotating shaft within the chamber. A simple ball cup is mounted on the shaft, in which three test balls are pressed. Balls as small as 2 mm can be used, providing the user is sufficiently skilled in handling such items. For ease of handling and measurement, 3 mm test balls are recommended.
A single upper test ball is super-glued to the end of the “needle” of a top-hat shaped spinning top. This ball is then engaged with the three supporting balls in the ball cup, to form the conventional sliding four ball test geometry.
With the chamber evacuated, the drive spindle is brought into motion and accelerated very slowly, such that there is no slip between the upper ball and the lower supporting balls. The shaft and the top are thus brought into motion together and the speed increased to that required for the test. Once the required running speed is achieved, the shaft is brought rapidly to rest and the top spins. Because of the vacuum environment, the only drag force on the top is the friction in the contact between upper rotating ball and the lower (now static) balls. The top decelerates as a result of this friction and eventually comes to rest. The number of cycles to come to rest is measured with a simple proximity sensor and data logging of pulses against time allows the changing velocity to be plotted.
Tests are performed as a progressive sequence of run-downs, with, in dry tests, the number of cycles for the top to come to rest decreasing as wear takes place. Tests may be run either dry or with a drop of lubricant on the contact. As the only measurement is digital (pulse counting proximity sensor) there is no requirement for calibration of sensitive force transducers.
The test load and inertia of the top are of course a function of the design and mass of the top itself, so tests are ideally run as comparative tests with a given top rather than attempting to derive absolute measurements of friction from an intimate knowledge of the inertia of the top.
| Test Configuration: | Miniature Four Ball |
| Recommended Ball Diameter: | 3 mm |
| Maximum Shafts Speed: | 1,000 rpm |
| Interface: | PLINT HSD High Speed Data Acquisition Interface |
| Software: | PLINT COMPEND 2000 Software |
| Rotational Speed | |
| Number of Run-down Cycles |
| Rotational Speed | |
| Number of Revolutions | |
| Time |
| Sliding Speed | |
| Sliding Distance |
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