Removal of malfunction of bulldozer
A bulldozer of type PD220, where the earth is weak during the earthwork construction of the subgrade. After field inspection, it is found that the engine power is normal, the transmission and torque converter filter is dirty, and hydraulic oil deterioration, which is estimated to cause failure. Thus, the magnetic coarse filter (see Figure) is removed and cleaned, and the filter core of the oil filter 3 is replaced with hydraulic oil in the transmission, but after a few hours, the bulldozer is unable to work again.
Because the mechanic can not remove the trouble, the machine will be sent back to the machine repair shop for repair. Measured by the mouth of C transmission clutch pressure of 2.0MPa (normal pressure should be 2.5MPa), due to low pressure, then suspect the speed pump wear serious, can not reach the rated pump oil pressure. After the new transmission pump was replaced, the machine was re tested and found to be still weak. Therefore, the suspect is due to the pressure regulating valve spool wear and low pressure. In the demolition of the pressure regulating valve, it is found that at the entrance to the oil there are two rubber mats to plug the valve core, so that the pressure regulating valve does not work, therefore, can not guarantee the joint of the clutch block, resulting in pushing the soil weak. After the rubber pad is removed, the bulldozer is restored to normal.
In this analysis of the source of rubber pad, a rubber pad is the same in the oil filter 3 are found, and put together a complete rubber gasket and pressure regulating valve port can be that the rubber gasket is from the old aging after falling into the oil filter on the road. This reminds of repair personnel, that must be carefully examined in the repair work, do not make the damaged wreckage falls in the body.