Fault analysis and analysis of BMW hydraulic vibratory roller

Fault phenomenon:

In the use of 2 BMW BW219D-2 hydraulic vibratory rollers, the following failures occurred: during the process of compaction, they suddenly stopped and could not walk before and after, but the hydraulic vibration was still valid.

Malfunction analysis:

The BMW BW219D-2 uses full hydraulic transmission, so its two functions of vibration and walking are fluid pressure supplied by the vibratory plunger pump and the walking plunger pump. According to the sudden breakdown of the fault and the observation on the spot, there is no sign of fault before it stops suddenly, and there is no abnormal sound at the same time. Therefore, it is preliminarily determined that the hydraulic system of the train is out of order. After the hydraulic test, it is found that the inlet of the hydraulic motor is free of pressure, and the piston pump outlet is also free of pressure. Therefore, the hydraulic system of the walking part is considered to be out of order. Because the hydraulic system of this model has been operated with many electronic components, the cause of the fault has not been known for a while. Based on the detailed inspection circuit to control the hydraulic system, found that the electromagnetic coil case a walking electromagnetic relief valve on the pump is very hot, with a multimeter test the voltage, but the electromagnetic coil ends tends to infinity, we can conclude that the electromagnetic coil has been burned. The analysis indicated that the solenoid valve relief valve plunger pump for walking, valve brake system, so when the solenoid valve coil short circuit, it will cause hydraulic pressure relief system and the rear wheel brake hydraulic lock, so the machine will suddenly stop.