Triangle Tire has developed a revolutionary new test method for obtaining a ton kilometer per hour (TKPH) rating for earthmover tires using an indoor test drum. There is currently no international unified standard for obtaining this rating. Compared with field testing, this new method is more accurate, cost-effective, efficient, easy to do, and can be globally standardized. It is different from that specified in SAE J1015, which obtains this rating by testing tires on vehicles and testing ground.
Test preparation
The vulcanized tire should be rested at ambient temperature for at least 24 hours. Drilling holes on the tire surface is a very important step in the whole test procedure. The location, depth and size of the drilled holes have significant impact on the error of the test data obtained during the test and the accuracy of the final test result. Holes with a diameter of 5mm ± 0.5mm should be drilled on the tread for temperature measurement. They should be located between the tread center line and shoulders. At least two transverse rows should be drilled, each with three or more holes, equally spaced around the circumference of the tire. Preferably, the holes should be located at the crown centerline and the center of the pattern blocks in the shoulder area. If a groove goes through the crown centerline, holes should be drilled 25mm away from the groove at each side, but no less than 12.5mm from the edge of the pattern blocks. The bottom of the hole should be at most 5mm away from the top of the topmost reinforcement and should not touch this layer.
At least three test speed values should be chosen within tire rated speed, as the speeds for the test drum. Take half of the tire rated speed as a reference speed, choose test speed values around this reference speed, and start the test from the minimum speed value. The test load should be 85% of the rated load capacity. The test pressure should be the pressure corresponding to the rated load capacity. Ambient temperature should be constant during the test, no less than 20℃ and be 38 ± 3℃.
Test method steps
There are eight key steps in the test procedure. First of all, the tire should be mounted on the measuring rim and inflated to the specified pressure. The tire-rim assembly must then be rested for 24 hours under ambient temperature. Then, adjust tire pressure to the specified value, and 15 minutes later, make the tire run at the minimum test speed under the specified load.
Next, measure the temperature of all test holes every hour. After the measurement, keep running the tire until the temperature remains stable. Finish temperature measurement within 15 minutes if it is safe to do so. The temperature should then be recorded for each probe point as well as the ambient temperature. Next, stop testing after the temperature on all probe points remains stable. Let the tire rest and cool down to the ambient temperature before each of the next test speeds so that tire separation will not occur due to internal overheating. Run the tire at the next test speed until the temperature remains stable. The above test procedure should then be repeated until tire failure, or finishing the test at the last selected test speed.
Take the maximum equilibrium temperature of each group of probe points at each selected test speed as the Y-axis and the products calculated by test load multiplying test speed as the X-axis to plot the TKPH value versus equilibrium temperature curve graph. The TKPH reading from the curve graph corresponding to the rating temperature given by tire manufacturers is taken as the TKPH rating of the tire.
Customer response
Triangle has provided its global mining customers with the TKPH rating obtained through the drum test method for its OTR tires and in doing so, guided customers in the selection of new products. Questionnaire feedback has shown that this TKPH rating plays an important role in tire application and customers are very satisfied with actual tire performance.
April 20, 2016
