Master these few tricks and you can easily handle the maintenance, repair and common faults of pavers

I. Matters needing Attention During Use

1.1 Always pay attention to adjusting and inspecting the idler wheels and tracks

Due to the heavy weight of the screed on the paver, the center of gravity of the entire machine is shifted backward. Therefore, during operation, the rear support wheels of the paver are subjected to the greatest force and are prone to damage. Once damaged, the paver will move up and down, and the screed will be uneven, resulting in a wavy road surface that directly affects the smoothness of the road surface. Therefore, during the operation of the paver, the distance traveled at one time should not be too long and the speed should not be too fast. During long-term high-speed driving, the idler wheels will generate high temperatures, and the lubricating oil will be diluted and leak out, causing damage to the idler wheels. Once a certain idler wheel is found to be damaged, it should be replaced in time; otherwise, the adjacent idler wheels will also wear out faster due to excessive force. When replacing the idler wheels, their wear conditions should be taken into account. If the degree of wear is small, they can be replaced one by one; otherwise, all of them should be replaced to avoid accelerating the wear of the newly replaced idler wheels.

The tension of the tracks on both sides should be moderate and consistent to prevent the paver from skipping teeth or deviating when moving, which may affect the smoothness of the road surface. The teeth of the drive wheels and the track plates of the track should both be in good condition; otherwise, teeth skipping and walking jolts will occur, affecting the smoothness of the road surface.

1.2 Always pay attention to and check the locking valve of the lifting hydraulic cylinder

The lifting hydraulic cylinder of the paver is floating during operation. When the machine stops, its lower oil chamber is locked to prevent the screed from sinking and causing unevenness on the road surface. Although the lifting cylinder is floating, there is still pressure in its oil supply chamber. This is because the material temperature will drop when the machine is waiting for materials, which increases the resistance of the screed when the machine starts again, and the road surface is prone to bulging. Therefore, in daily work, the condition of the locking valve, the locking pressure of the oil chamber and the sealing performance of the hydraulic cylinder should be frequently checked to avoid affecting the paving quality during the paving process.

1.3 Reasonably control the paving speed

During the paving process, the paver should move forward at a constant speed. The paving speed is best matched with the output of the asphalt mixing plant, and the number of times the paver stops should be minimized as much as possible. Changing the paving speed will cause a change in the density of the road surface. When the roller compacts, uneven settlement will occur, resulting in a deterioration of the road surface flatness. If the paving speed is too fast, it is easy for the machine to always be in a state of waiting for materials, causing indentations on the road surface due to the self-weight of the screed, which affects the smoothness of the road surface.

1.4 Use the automatic leveling instrument and the material level sensor correctly

The automatic leveling instrument and the material level sensor are two very important components. Whether they work normally or not directly affects the quality of the paved road surface. They are required to be connected in a power-off state. During construction, different sensitivity Settings should be selected based on different usage conditions. Then, the position and direction of the longitudinal and transverse controllers should be set according to the situation. During the period of waiting for materials, the diesel engine can be turned off, but the entire machine must not be powered off. Otherwise, it is easy to cause changes in the cross slope. When using the steel wire rope as the tension line, the tension line should not exceed 40 cm, and there should be a distance of 30 cm to 50 cm from the road surface to be paved.

The ultrasonic material level sensor should be aimed at the position in the material distribution trough that is most sensitive to the material distribution speed and the forward speed of the paver. This position is generally in the middle of the openings at both ends of the material distribution trough. Only in this way can the smooth distribution of materials be guaranteed. Continuous operation ensures flatness and density. The height adjustment range of the material level sensor is quite large. However, once the position is fixed, the adjustment range is often very small and generally does not need to be moved after adjustment.

1.5 Use and install the ironing plate correctly

To ensure the smoothness of the road surface paving, it is first required that the entire screed base plate itself be a flat surface. When users install an extended iron plate, they often only pay attention to the alignment of the rear end of the iron plate but neglect the alignment of the front end. This needs to be corrected. In addition, when laying asphalt, the screed should be heated. Even in hot weather, the heating time should not be less than 20 minutes. If the temperature of the screed is not high enough, the asphalt beneath is prone to stick to the base plate, causing "pitting" on the road surface and requiring manual replenishment. Spraying a small amount of diesel on the base plate of the screed before construction can also reduce the adhesion of asphalt on the base plate. Finally, the elevation Angle of the ironing plate and the stroke of the rammer should be adjusted reasonably. When laying asphalt, the thickness is generally not large, and the elevation Angle of the screed is mostly adjusted to zero. The stroke of the rammer should be reduced, usually 3 for the front and 5 for the rear. When laying the asphalt underlayer of the road with poor quality, the stroke can be appropriately adjusted to 6 in the front and 5 in the back.

Ii. Maintenance and repair of pavers and troubleshooting of common faults

(1) When using new machines, it is essential to attach great importance to the maintenance during the running-in period. Do not neglect the maintenance during the running-in period just to catch up with the project schedule. Otherwise, it will accelerate the abnormal wear of some components and leave hidden dangers for machine malfunctions. After the running-in period is over, necessary compulsory maintenance must be carried out. In daily use, it is essential to strictly follow the maintenance manual for timely maintenance and repair. The maintenance of the machine mainly involves lubrication, including timely addition and replacement of engine oil, grease, gear oil and hydraulic oil, etc. If the engine oil is not changed in time or substandard oil is used, it may cause the engine to burn oil.

In addition, timely cleaning or replacement of the air filter element, idling for 3 minutes to 5 mm when starting and stopping, and using qualified diesel are all necessary measures to prevent the machine from burning oil. For systems that use automatic lubrication at key lubrication points, when the temperature is below around 20℃, No. 2 grease should be used.

The automatic lubrication pump and the progressive distributor are equipped with plunger pairs, which fit very precisely. Therefore, the cleanliness of the grease is required to be very high, and there must be no solid impurities. Otherwise, it will cause faults such as wear of the lubrication pump plunger, jamming of the check valve, bending of the plunger, motor burnout, and jamming of the distributor. If the spare grease nipple of the automatic lubrication point leaks oil, a new one with good reverse sealing performance should be found and replaced. High-temperature grease is only necessary when laying asphalt materials.

(2) Lubrication of the scraper feeding chain: The scraper feeding chain comes into contact with the material and works in a harsh environment. If it is not lubricated, it will lead to rust, material adhesion, chipping, accelerated wear of the feeding chain and the bottom plate, and even material jamming and chain breakage.

It is recommended to use a mixture of various waste lubricating oils and diesel for the lubrication of the scraper conveyor chain. Diesel has strong permeability and is conducive to entering the interior of the chain. Before lubrication, the material transfer and distribution switch should be opened first to clear the material in the gap, and then the cover plate in front of the hopper should be lifted. Pour the mixed oil onto the chain. Lubricate once every 1 to 3 days, after each construction.

(3) Regularly check whether there are any abnormal sounds during the paving operation of each working device, whether the engine, mechanical transmission system and hydraulic system of the paver are overheating, and whether there is any slippage during the operation of the paver.

(4) Analysis and elimination of some common faults.

1. Engine speed drop during the laying process: Check if the load of the leveler is uneven, if there is any rupture or leakage in the fuel supply circuit, if the intake circuit and filter are clogged, if the engine fuel is qualified, and if it contains water. The system does not work without hydraulic oil output. Check whether the hydraulic pump is rotating; Is the fuel in the fuel tank sufficient? Check if the oil suction filter and pipelines are clogged. Check the vacuum gauge of the oil suction filter. Replace the filter when the pressure is 25 kPa. Measure the pressure on the pressure circuit. If the pressure is very low, check and replace the relief valve. The pump does not discharge oil. Replace the pump or pipeline. Pressure fluctuation, eliminate the air intake phenomenon of the suction pipe.

2. The output hydraulic oil fails to reach the preset parameters: Check the pressure of each branch pipe and the output pressure of the oil pump, as well as measure the rotational speed of the oil pump and the motor. Connect the pressure gauge to measure the pressure. If the pump or motor is damaged, replace them.

3. Excessively high oil temperature: Check the oil level in the fuel tank; The contamination condition of the oil filter element; The operating status of the pump and motor. Refueling; Replace the oil filter element; Check the working condition of the relief valve and replace it as needed. Replace the damaged parts of the pump and motor.

4. High noise: Check if there are any bubbles in the oil in the fuel tank. Check if the pipe fixation points are loose. The working status of the pump and motor. If the fuel is insufficient, add more oil. Reinforce loose connections to prevent resonance; Damaged components should be replaced in a timely manner. Expel the gas in the hydraulic circuit.

With the application and improvement of new technologies, today's pavers are all equipped with computer fault diagnosis systems, which can accurately and promptly detect fault phenomena and locate the source of faults. Coupled with the fault diagnosis experience accumulated during use, this can ensure the normal and continuous operation of the paver, and when mechanical faults occur. Early detection and elimination can fully ensure that the paver can play its due role in a large number of highway construction projects.