Fault Analysis of the sudden stop of the scraper of VOGLE1800 Asphalt Paver

Analysis of the reasons for the weak operation of the scraper of the paver

The VOGLE asphalt paver adopts two independently controlled scraper feeding systems on the left and right. The left and right scrapers are independently driven. The independent hydrostatic system drives the left and right scraper motors. The two oil motors are transmitted through the reducer, sprocket and chain transmission mechanism, which can drive the scraper feeder shaft independently or simultaneously, making the scraper feeder rotate.

The reasons for the sudden lack of power and cessation of rotation of the scraper conveyor may come from three aspects, namely the hydraulic system, the mechanical transmission system and the circuit system.

1.1 Hydraulic system failure

Since only the right scraper feeder of the paver does not rotate while other systems are working normally, it indicates that there is sufficient oil in the system, the oil performance is good, and the oil suction filter is not clogged. The possible causes of the fault are:

(1) The hydraulic pipeline burst. The oil inlet and outlet pipelines burst, causing the right scraper feeding motor to fail to rotate.

(2) The relief valve is damaged due to poor sealing between the valve body and the valve seat, the valve core being stuck, the spring being damaged, or the pressure setting being too low, causing a large amount of pressure oil to directly return to the oil tank, and the system is unable to establish sufficient pressure.

(3) The control valve of the scraper conveyor is faulty. The valve core and the valve body are excessively worn. The valve core and the valve body are sealed with a gap. Excessive wear leads to excessive internal leakage. The valve core and the valve body are stuck. The valve core does not move flexibly or cannot move at all, and the oil passage cannot be opened or closed correctly. The system cannot work normally.

(4) Motor failure of the right scraper feeder: The scraper feeder motor adopts an inner curve rotor motor. The working surface or end face of the motor is severely worn or has serious scratches, which reduces the volumetric efficiency of the motor and results in no power output.

(5) The right scraper feeder pump is damaged. The scraper feeder pump uses a plunger pump. The plunger and the cylinder block hole, the sliding shoe and the swash plate, the distribution plate and the distribution surface of the cylinder block are severely worn, with excessive internal leakage, reduced volumetric efficiency and mechanical efficiency, and a decrease in the displacement of the hydraulic pump.

1.2 Main Faults of the Circuit system

(1) The fuse blew

(2) The relay is damaged

(3) The solenoid valve does not act when powered on due to poor contact in the power connection, voltage fluctuations beyond the allowable range, short circuit or burnout of the coil, resulting in the solenoid valve not acting when powered on and failing to correctly control the oil circuit.

(4) Poor contact of the power supply wiring for the speed control switch of the scraper feeder or damage to the switch

(5) The installation position of the scraper level gauge is incorrect, the power connection has poor contact, or the level gauge is damaged

1.3 Main faults of the mechanical transmission system

(1) Scraper chain failure

The scraper chain is too loose and scratches against the ground.

The B asphalt mixture was mixed with impurities such as steel bars, which jammed the scraper chain and prevented the scraper from rotating.

The connecting bolts of the C paver's base plate are loose or the base plate is cracked and warped, which will jam the scraper feeder.

The scraper chain on the right side of D is broken.

The bearings at both ends of the E scraper chain are damaged. Generally, it is due to the damage of the oil seal and dust seal sleeve outside the bearing. After the asphalt mixture enters, it causes the scraper to get stuck or the resistance to be too large, resulting in the damage of the bearing.

(2) Faults in the sprocket and chain transmission mechanism

The chain A was jammed. Iron debris entered between the chain and the sprocket transmission mechanism, causing the chain to be jammed.

Chain B broke. The chain broke under the action of impact load.

The teeth of the C sprocket are broken or severely worn. Due to poor processing quality, the teeth of the driving and driven sprockets are broken or severely worn.

The spline (flat key) connecting the driving and driven sprockets is damaged.

(3) The reducer is damaged

The bearing of reducer A is damaged. The support bearings at both ends of the driving and driven shafts of the reducer are burned out or fall apart, causing the output shaft of the reducer to have no power output.

The gears of reducer B are damaged. Excessive wear of gears or breakage of individual teeth prevent power from being transmitted normally.

The meshing clearance adjustment of gear C is incorrect. Normal meshing transmission cannot be carried out.

The spline (flat key) connecting the driving and driven gears is damaged.

Iron debris entered the E gearbox and jammed the gears.

Troubleshooting for the inability of the scraper feeder to rotate

2.1 Troubleshooting of Mechanical Systems

The faulty parts of the mechanical system include the scraper feeder, sprocket, chain drive mechanism and reducer. The faulty part can be initially determined by touching the temperature of the casing and listening for abnormal sounds, and a detailed inspection of each component should be carried out.

(1) Inspect the sprocket and chain drive mechanism, check the damage of each part, and repair or replace the damaged parts.

(2) Maintenance of the reducer: Remove the reducer and rotate the input shaft of the reducer with a pipe wrench. If it can rotate flexibly and there is no abnormal noise and the housing temperature is normal when initially confirmed, it indicates that the reducer is working well. If it cannot be rotated, the left and right reducers can be swapped for further diagnosis. When necessary, disassemble the reducer, inspect the damage of each part, and repair or replace the damaged parts.

(3) Inspect the scraper conveyor. Remove the asphalt mixture on the scraper conveyor and check and adjust the length of the scraper chain. Check whether there is any movement interference in the scraper chain. Check whether the bearings at both the front and rear ends of the scraper feeder are burned out or disassembled. If the bearings are damaged, replace them with new ones.

2.2 Circuit Fault Elimination

(1) Check the fuse. If it is damaged, replace it with a new one of the same model

(2) Check the relays. Swap the relays of the left and right scraper conveyors for inspection. If they are damaged, replace them with new relays of the same model

(3) Check and ensure that the material level gauge is installed in the correct position, the power connection is in good contact, and the material level gauge is working properly

(4) Check and ensure that the wiring of the power supply for the speed control switch of the scraper feeder is in good contact and the switch is working properly

(5) Check the solenoid valve. Check and ensure that the power connection is in good contact, the power voltage variation is within the normal range, and there is no short circuit or open circuit in the coil. Replace the solenoid valve with a new one if necessary.

2.3 Troubleshooting of Hydraulic System

(1) Check the relief valve. After reversing the relief valves of the left and right circuits, conduct a test run for inspection. If it is confirmed that the relief valve is faulty, check whether the spring is damaged, whether the sealing surface is well sealed, and whether the damping hole is blocked. If there is any damage, the relief valve should be replaced and the set pressure of the relief valve should be checked to ensure it complies with the regulations.

(2) Inspection of the scraper conveyor pump and motor: Start the engine to ensure that both the hydraulic oil and the engine are within the normal temperature range. Run the engine at the rated speed and listen for any abnormal sounds from the scraper pump and motor, as well as whether the casing temperature is too high. If there is suspicion of a problem with the motor or pump, you can further confirm it by swapping them left and right respectively. When necessary, disassemble the hydraulic pump or motor to check the wear condition of the pump (motor) and whether the seals are in good condition, etc. If there is any deviation or damage, it should be repaired or replaced.

(3) Disassemble and inspect the control valve of the scraper feeder to check if there are any scratches on the sealing surface between the valve core and the valve body and whether the seal is good. If there are defects on the sealing surface, they can be repaired or replaced by grinding as the situation requires.

3. Conclusion

In conclusion, the fault of the sudden stop of the scraper conveyor of the VOGLE-1800 asphalt paver is rather complex to analyze and handle. Therefore, during the operation of the paver, the equipment should be operated, maintained and serviced strictly in accordance with the regulations. Any problems found should be dealt with in a timely manner to reduce the occurrence of faults and improve the integrity rate of the equipment.