Analysis of the Reasons for the weak lifting and flipping of the loader bucket

When a loader is in operation, we often encounter situations where the boom lifting in the hydraulic system is weak (slow speed) or the bucket flipping is weak. To solve this problem, we need to first analyze the causes:

When a diesel engine is in operation, its rotational speed does not increase significantly. When the boom and the slide valve of the bucket reversing valve are in the neutral position, press the engine accelerator pedal all the way down. If the diesel engine speed does not reach the rated speed, it may be a diesel engine failure, and the cause of the low diesel engine speed should be checked.

When the throttle is small, the boom lifts slowly (or the boom cannot be lifted) and the bucket rotation is weak. When the throttle is increased, it works normally. The causes of this malfunction are as follows:

If the working pump is severely worn or damaged, it should be replaced.

b. The opening pressure of the pilot-operated safety valve is too low or the seal is not tight. The pressure of the working hydraulic system should be measured with a pressure gauge. If the pressure is too low, it should not be adjusted blindly. First, the safety valve should be removed to check whether the pilot valve spring is broken, whether the seal is good, and whether the main valve core is stuck, etc. Then make adjustments according to the situation.

c. Damage to the sealing ring of the hydraulic cylinder piston or wear of the cylinder barrel (with pull marks) causes leakage inside the cylinder. To determine whether the cylinder is leaking internally, you can retract the cylinder to the bottom, then loosen the oil pipe in the rodless cavity to allow the rodless cavity to continue filling with oil. If a large amount of hydraulic oil comes out of the rodless cavity, it indicates that the cylinder is leaking internally and the cylinder should be inspected and repaired.

⑶ It works normally when the throttle is small, but becomes weak when the throttle is large. This situation is mostly caused by air leakage in the low-pressure oil circuit of the working hydraulic system. The sealing condition of the low-pressure oil circuit should be checked.

a. The oil level in the hydraulic oil tank is too low, causing the working pump to be sucked empty and resulting in insufficient oil suction.

b. Poor sealing of the oil inlet pipe of the working pump or aging of the rubber hose allows air to enter the oil pipe. Due to the compressibility of air, the system pressure is insufficient.

c. The working pump is leaking air, causing air to enter the working hydraulic system.

In addition, if the grade of hydraulic oil does not meet the requirements, it may also cause weak loading and unloading. The hydraulic oil should be replaced as required.