Troubleshooting Of Loader Working Devices

The speed of the loader arm is slow when lifting and closing the bucket

When this happens, first check whether the oil pump level in the fuel tank is too low, resulting in insufficient oil absorption or emptying of the high-pressure pump; whether the oil return filter is blocked and the oil return is not smooth, thus causing the oil level in the fuel tank to be low; the filter should be washed frequently to maintain Clean and add enough hydraulic oil. Secondly, check whether the gear pump leaks internally, so that the volumetric efficiency of the high-pressure pump cannot meet the requirements; whether the sealing condition of the oil inlet pipe is good, whether there is air entering the system, resulting in insufficient pressure; whether the connection of the gear pump inlet and outlet pipes is accurate. After checking and eliminating the hidden dangers in the above parts, check the boom cylinder and boom control valve, dump cylinder and dump control valve for internal leakage.

After analysis and specific practice, we found an easy way to quickly diagnose and troubleshoot:

(1) Fill the loading bucket with a full load and lift it to the limit position; then put the boom control lever in the neutral position, turn off the engine, stop the hydraulic pump supplying oil, and observe the sinking speed of the boom; then put the boom The joystick is placed in the rising position. If the sinking speed of the boom is significantly accelerated at this time, the cause of the internal leakage is the automatic arm control valve. Similarly, similar methods can be used to determine the inability of the bucket to retract the bucket according to the expansion and contraction of the tipper cylinder when the joystick is in the neutral position and the rearward tilt position.

(2) Check whether the piston sealing ring of the boom cylinder is damaged. Retract the piston of the boom cylinder to the bottom, and then remove the rodless cavity oil pipe, so that the rod cavity of the boom cylinder continues to be filled with oil. ), indicating that the piston sealing ring is damaged and should be replaced immediately.

(3) If the O-ring of the distribution valve is aged, deformed or worn, the exposed part of the valve stem is corroded, resulting in damage to the sealing surface, which will cause leakage outside the distribution valve. At this time, the O-ring should be replaced. If the end of the relief valve stem is severely corroded, the corroded part can be ground off, and then brazed to restore it to the original diameter and polished smoothly. If the valve core and valve sleeve of the distribution valve are seriously worn, it will cause internal leakage. At this time, the distribution valve should be replaced. If conditions permit, the surface of the valve core can also be chrome-plated, and then matched with the valve sleeve to grind to make the matching gap reach 0.006 ~ 0.012 mm and no sticking phenomenon.

(4) Such problems will also occur when the opening pressure of the pilot safety valve is too low. At this time, the pressure regulating screw of the total safety valve cannot be blindly adjusted. The safety valve should be disassembled and inspected to see whether the pilot valve spring is broken, whether the pilot valve is well sealed, whether the main spool is stuck and whether the damping hole of the main spool is blocked. If there is no problem with the above, the opening pressure of the safety valve should be adjusted. The method of adjusting the pressure is: first unscrew the screw plug on the distribution valve, connect the pressure gauge, then start the diesel engine and control its speed at about 1800r/min, then place the rotary bucket slide valve in the neutral position, and lift the boom. To the limit position, make the system pressurized, then adjust the pressure regulating screw until the pressure gauge reading reaches the specified value.

Common fault analysis and elimination of loader working device Common failure analysis and elimination of loader working device