When diagnosing faults in hydraulic systems, it is essential to focus on the conditions required to complete a specific action, identify which conditions have been met, and determine which conditions may not be met to pinpoint the fault. The logical chain includes every step from the initial signal to the final action of the actuator, the state of each step during the process, and the physical quantities and input conditions required.
Pumping System Faults
1. Piston Rod Not Moving
(1) Pump start button fault, loose connections, broken wires, or moisture in electrical components.
(2) Relief valve malfunction.
(3) Electro-hydraulic directional valve fault, typically due to a stuck pilot valve core or a burnt solenoid.
(4) Insufficient control pressure in the pressure reducing valve.
2. Main Cylinder Piston Moving Slowly and Weakly
(1) Damage to the main cylinder check valve.
(2) Low control pressure in the pressure reducing valve.
(3) Blockage in the control oil circuit throttle.
(4) Damage to the main cylinder piston seal causing severe internal leakage.
(5) Severe wear in the main oil pump, preventing pressure buildup.
(6) Low pressure setting in the main relief valve.
3. Main Cylinder Not Reversing (Fault Analysis)
(1) Stuck valve core in the hydraulic directional valve controlling automatic pumping.
(2) Blocked throttle hole in the hydraulic control oil circuit.
(3) Check for input and output signals in the electro-hydraulic directional control and the functionality of the main cylinder proximity switch
Distribution System Faults
1. S-Tube Not Swinging
(1) Distribution valve jog button fault or loose wiring.
(2) Stuck pilot valve core in the hydraulic directional valve.
(3) Faulty pilot relief valve resulting in insufficient switching pressure.
(4) Faulty constant pressure pump failing to provide adequate switching pressure.
2. S-Tube Swinging Weakly
(1) Insufficient pressure or damaged bladder in the accumulator. The accumulator supplements the energy required for the S-tube distribution valve to swing instantaneously. Faults include insufficient pressure or bladder damage, leading to weak or no swing.
Quick test method for accumulator charging pressure.
(2) Unclosed unloading switch.
(3) Faulty solenoid or broken spring in the electro-hydraulic directional valve, preventing the main valve core from reaching the correct position. Wear in the main valve core causing internal leakage.
3. Common Causes and Solutions for Erratic S-Tube Movement
(1) Stuck or blocked discharge check valve in the signal oil.
(2) Stuck logic valve core.
(3) Damaged seals between logic valve cavities.
(4) Stuck hydraulic valve core.
(5) Stuck valve core in the main hydraulic directional valve.
(6) Blocked filter screen in the filter joint.
(7) Blocked damping plug in the hydraulic control port.
Lubrication System Faults
1. No Oil Output or Reduced Oil Output
(1) Stuck valve core in the lubrication pump.
(2) Stuck piston in the lubrication oil tank.
(3) Broken or stuck check valve.
2. No Oil Output at Lubrication Points
(1) Stuck oil distributor.
(2) Faulty lubrication pump.
(3) Blocked lubrication points.
3. Oil Pump Unable to Add Oil
(1) Stuck check valve in the oil pump.
(2) Stuck piston in the lubrication oil tank.
(3) Blocked outlet oil filter.
By focusing on these common faults and their respective solutions, you can ensure the effective and efficient operation of concrete machinery, enhancing the overall reliability and performance of hydraulic systems in concrete pumps.
