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Maintenance of DRF450 Reach Stacker Transmission Oil Temperature High which Causes Unable to Walk

Quick maintenance of the DRF450 reach stacker gearbox oil temperature causing the locomotive to fail to run normally.

Description of failure

When a DRF450 reach stacker is used in high temperature weather with an ambient temperature exceeding 30ºC, after a period of operation, the Kalmar Information Terminal Display Unit (KIT) in the locomotive cab displays a high transmission oil temperature alarm, and the transmission oil temperature is displayed on the display. It was as high as 100ºC, the locomotive could not run normally and entered the “limp home” mode.


The maintenance personnel used a handheld infrared thermometer to measure the temperature of the gearbox at 97ºC. This value is close to the data on the locomotive display, indicating that the gearbox does have a high oil temperature. Check that the transmission oil level is normal when the reach stacker is idling. Check the customer car maintenance records and find that the transmission oil and filter element have been replaced recently. Check the transmission oil radiator, there are plastic bags, paper and other sundries below. After removing the sundries, clean the surface of the radiator with a low-pressure air gun, and after using it for about 50 minutes, the transmission will alarm again with high oil temperature.
When the high temperature alarm occurs, use the infrared thermometer to check the radiator again. The temperature of the oil inlet pipe is 95ºC, the temperature of the oil return pipe is 92ºC, and the surface of the radiator is about 93ºC. The above measurement data can infer that there are three possible reasons for the failure:
1. The transmission oil cooling system does not play a role in cooling;
2. The failure of the transmission control valve or the slippage of the internal gear hub generates extra heat, which causes the oil temperature to be too high;
3. The abnormal operation of the torque converter causes the transmission oil temperature to be high;
First check the transmission control valve and gear hub for abnormalities. After the engine is turned off and the power is turned off, check that the wiring harness between the transmission valve group and the controller is normal, there is no short circuit or open circuit, and the resistance value of each proportional solenoid valve coil is about 4.5 ohms. Select the solenoid valve coil resistance value of 27 ohms, and the pressure sensor resistance value of about 2200 Ohm, no abnormality was found in the electrical system inspection.
Then connect an external pressure gauge to the transmission control valve, and measure the forward gear (64), reverse gear (65), 1/3 gear (60/62) of the transmission in turn when the locomotive is running, according to the pressure measurement point distribution diagram of the control valve (below). ), 2/4 gear (66/61) after the solenoid valve pressure, the pressure value is maintained at 22bar. Moreover, the pressure value is the same as the pressure value of each gear hub measured on the gearbox casing, indicating that the gear hub of the gearbox is in good condition and there is no problem of pressure relief and slippage. Failure checkpoints (58/59) where multiple gear hubs work simultaneously also did not detect pressure. According to the above test results, the transmission valve group and the internal gear hub are running normally. According to the working principle of the gearbox, the high-temperature oil output from the torque converter is cooled by the radiator, and finally merges with the oil used for lubrication and returns to the gearbox oil pan together. The output pressure and flow of the torque converter will also affect the heat dissipation effect of the transmission oil. Therefore, it is necessary to check whether the output pressure of the torque converter is normal.
According to the above inspection results, it can be judged that the transmission oil radiator is the problem that affects the high temperature of the transmission oil. Carefully check the transmission radiator, and found that the thermostat on the radiator is not the same as the thermostat matched with the original car, and there are fewer fins on the radiator, and the heat dissipation effect is not ideal.
Through the comparative analysis of the unqualified radiator and the original radiator, it can be found that the processing technology of the unqualified radiator is poor, the cross-section of the heat dissipation channel is small, and the thermostat works unreliable. However, the original radiator provided by Kalmar has a large number of cross-section layers, and the total heat dissipation area, cooling effect and service life of the original radiator are much higher than those of the above substandard products.
The poor heat dissipation effect of the radiator and the failure to meet the normal use requirements is the root cause of the high transmission oil temperature alarm when the locomotive is in a high outdoor temperature condition.


After communicating with the customer, after purchasing the original Kalmar radiator and replacing it, the test run worked normally.

Case Summary

In order to ensure the safe and efficient operation of customer locomotives, we often remind customers of the importance and necessity of using Kalmar original parts, so as not to affect the normal use of the locomotive and cause unnecessary downtime.
In the daily troubleshooting of equipment, it is sometimes impossible to accurately find the root cause of the failure. At this time, we may use the “reverse inference method” to analyze the failure. Through careful analysis, we can list various options that may cause the failure. According to the principle of “from easy to difficult, from outside to inside”, the doubtful options are eliminated one by one, and the last remaining option is that we want to find the answer.
At the same time, please pay attention to check whether the radiator is dirty and blocked by foreign objects when maintaining the locomotive.

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