A Brief Discussion on the Maintenance of CAT AP755 Asphalt Concrete Paver

The CATAP755 paver is a new generation of multi-functional asphalt paver that has been comprehensively improved with the latest technology. It mainly consists of the superstructure, main frame, feeding equipment, power system, control system, hydraulic system, electrical system, leveling system, and central centralized lubrication system. Equipped with an electronic management system for pavers in multiple languages, it features comprehensive monitoring functions, significantly extending the trouble-free working time. Equipped with an electronically controlled engine with a power of 149kw that meets Euro III emission standards, and matched with Caterpillar's high-performance heavy-duty screed, it realizes the powerful functions of the multi-functional paver, making operation more comfortable and convenient, and can achieve ideal paving results in the harshest working environments. When laying the asphalt layer, it can effectively eliminate the segregation phenomenon of the hydraulic telescopic part and the mechanical assembly part that is inherent in other pavers, and the surface flatness is extremely high.

In order to enable the AP755 paver to better exert its superior performance, it is necessary to maintain it. Careful maintenance not only improves the appearance of the paver, but also extends its service life and enhances its working reliability. The following mainly discusses the maintenance of this type of paver during its use.

Before the use and maintenance of pavers, all operators, maintenance and repair personnel of pavers should be trained. Only those who pass the training can take up their posts. All of them must wear safety protective clothing, read and master the operation and use manual carefully, and be proficient in all the operations and mechanical maintenance points of the paver. Strictly follow the maintenance, repair and inspection cycles specified in the user manual. The standards of all kinds of oils and coolants used for maintenance must comply with the manufacturer's regulations, and they must be genuine products. It is best to use the same brand and model of oil and coolant for the first maintenance.

Maintenance during the running-in period

The running-in period is the most crucial stage in the operation of new machinery, as it directly affects the service life of the machinery. Improper maintenance during the running-in period will accelerate the abnormal wear of each component, and in severe cases, it may cause damage or scrapping of each component. During the running-in period, it is essential to strictly follow the user manual for operation and maintenance. If any abnormal conditions occur with the new machinery, the manufacturer should be informed immediately. Under the guidance of the manufacturer's professional technical experts, compulsory maintenance or upkeep should be carried out, and records should be kept.

1.1 Maintenance of AP755 paver before its first use

Due to long-distance transportation, it is necessary to first check whether the new paver has been collided or damaged during the transportation process. Then check the tightness of each component, mainly whether the connection of the ironing plate and its accessories is firm, whether the installation of the screw cloth device is correct and firm, whether the belt of the diesel engine is intact, and whether the tightness meets the requirements, etc. The protective wax seal on the surface of the new paver should be removed, and the exterior of each component of the paver should be inspected for any leakage. It should be pointed out that the AP755 spiral distributor adopts hydraulic lifting, which brings great convenience to its use and maintenance.

Secondly, it is necessary to inspect the electrical, pneumatic and lubrication systems. Whether the battery is in good condition and whether it is installed correctly. Check whether all electrical systems, fuses, circuits and the joints of each electrical appliance are in good condition and whether the connections are correct. Whether the gas heating system is in a normal working condition; Check if the gas cylinder and hose are securely fastened and if there is any gas leakage. Is there any fire extinguishing equipment? Carefully check whether the oil level and quality of the diesel engine oil meet the requirements. It is best to change the oil. Whether the quantities of fuel, coolant, hydraulic oil and gear oil are sufficient and whether their qualities meet the requirements. Apply grease to all the parts of the paver that are lubricated with grease.

Finally, check the control system and the engine. The AP755 adopts CAN-BUS BUS control technology and CAN automatically diagnose faults. The service engineer sets all the adjustments on the control console to the neutral or zero position, pulls out the emergency stop button, turns on the ignition key, and allows the random computer to inspect the entire machine. Only when there are no faults can the engine be started.

After the engine starts, it should run at medium speed. Check whether all the instruments are normal, whether the oil pressure meets the requirements, and whether all the components are leaking or loose. Work does not start until the water temperature meets the requirements.

Another experience we have when using pavers is that the hydraulic oil must not be added in excess. Excessive addition of hydraulic oil can cause the oil temperature to rise and its volume to increase. As a result, the hydraulic oil will flow out from the vent of the hydraulic oil tank, causing oil leakage. If the pressure is too high, the high-temperature and high-pressure hydraulic oil may also spray out and cause injury. As the vent ports of the hydraulic oil tank are interconnected, if too much hydraulic oil is added and the temperature rises, it will cause excessive pressure inside the hydraulic oil tank, leading to its rupture. As a result, the high-temperature and high-pressure hydraulic oil will splash out, injuring people or damaging the oil pump and oil pipes. Therefore, during the maintenance and repair process, it is necessary to ensure that the quantities of fuel, coolant, hydraulic oil and gear oil are sufficient, but a comprehensive consideration should be given. For instance, the amount of hydraulic oil should not be excessive either.

1.2 Maintenance of the AP755 paver during operation

During the operation of the paver, the main tasks are to monitor various dynamic data and the lubrication conditions during continuous operation. For instance, if the engine speed meets the requirements specified by the manufacturer (2300r/min), the paver should not operate at full load. It is best to control it at 80% of the load (full-load operation only after the running-in period ends). From time to time, check the various instruments on the console and the data and prompts displayed on the computer for any abnormal phenomena.

The AP755 adopts central self-lubrication and does not require manual lubrication, which is very convenient. Maintenance engineers only need to regularly check whether there is sufficient grease in the central grease pump and should always maintain an adequate amount of grease. If the model with a central grease pump is not selected, grease should be added to each grease point regularly (every 3 to 4 hours).

One more point to note is the ultrasonic level sensor. The AP755 ultrasonic sensor adopts proportional control and is convenient to use. However, it should be noted that the ultrasonic emission line of the sensor needs to be perpendicular to the material surface.

1.3 Maintenance of the AP755 paver after its operation is completed (or interrupted)

It is essential to remember to maintain the paver after it has completed a day (or a period of time) of operation. The paver should be parked on a ground with load-bearing capacity and flatness. The tracks should be supported with wooden blocks, and the screed should be padded with wooden boards. Start the central grease pump to force grease to the lubrication points of the entire machine (for models without a central grease pump, apply grease to the first lubrication point) until the old grease is squeezed out, and then fill the central grease pump with grease. Turn off all control components and function keys. Do not shut down the engine until it has been running under no-load for 5 minutes. After the overheated parts of the paver have cooled down, clean the paver and remove all the paving materials adhering to the paver and the screed. Finally, check whether all the components of the paver are leaking.

The AP755 paver has a very good feature: the bottom plate of the scraper conveyor is highly wear-resistant, making it the most wear-resistant machine we have ever used. It is also equipped with an automatic diesel spraying cleaning function, making maintenance very convenient.

Maintenance for the AP755 paver at the end of its running-in period (1000 hours of operation)

Generally speaking, the first 1,000 hours of a paver's operation are the running-in period. After this period, all kinds of oils, coolants and filter elements of the entire paver need to be replaced. It is necessary to inspect and adjust the engine's belts, various transmission chains, drive chains and other components that require adjustment. Check for any leakage in each component, whether the connections are loose and intact.

Daily maintenance of the 2AP755 paver

In addition to conducting the above-mentioned necessary inspections and maintenance on the paver, carrying out daily maintenance is an important condition for extending the service life and efficiency of the paver. Daily maintenance should be carried out in accordance with the requirements specified in the user manual. If there are special needs, repairs or replacements should be made. The main points are as follows.

The first step is to inspect the oil circuit and lubrication system to see if the quantities of engine oil, fuel oil, coolant and hydraulic oil are sufficient, if their qualities meet the requirements, and if there is any leakage in each component. If necessary, they should be replenished or replaced in a timely manner.

Check whether the central grease pump is working, whether the grease is sufficient and whether its pipelines are unobstructed. For the model without a central grease pump, grease must be added to the grease points of the entire machine three times every working day within 10 hours, before, during and after the operation. If the working time exceeds 10 hours, 4 to 5 times should be added, and an additional 1 to 2 times should be added during the operation.

The second is to check the tightness of the connections of the paver. This includes whether the connection is firm and intact, especially ensuring the tightness of the left and right track beams, the ironing plate, the material distribution device, and the scraper conveying device. Check the tension of the drive belt and chain as well as their wear condition.

Thirdly, the paver should be cleaned frequently and the electrical, gas and heating systems should be inspected. It is necessary to promptly remove asphalt, adhered sand and other substances from the surface of the paver, as well as old oil, dust, debris and dirt from the surfaces of the engine, hydraulic components and other parts. Check and clean the air filter; Inspect all kinds of vulnerable and easily aged parts, and make timely adjustments or replacements when necessary. Check whether each electrical system, fuse, circuit and the connection of each electrical appliance are in good condition and whether they are loose. Before each operation, let all working devices run no-load to check if they are operating normally. At the same time, check whether the nozzles, connecting pipes, gas tanks and all switches of the heating system are normal.

We once encountered such a situation: During one operation, the engine automatically shut down due to the lack of diesel because the operator failed to add diesel in time. After refilling diesel, the engine still failed to start. Upon inspection, it was found that the high-pressure oil pump of the diesel engine was burned out and jammed due to lack of oil and unclean oil at the bottom of the fuel tank, which made the high-pressure oil pump unable to work and caused the engine to fail to start. Later, in response to this situation, strict requirements were imposed on the operators to add fuel promptly, shorten the engine's maintenance cycle, and install a first-stage diesel filter.

Regular maintenance of 3AP755 paver

The regular maintenance period of the paver must be carried out strictly in accordance with the time stipulated in the maintenance manual. If necessary, maintenance can be conducted in advance, but the maintenance period must not be extended. The maintenance period is determined based on the design of the paver to meet the normal operation requirements of all components. Regular maintenance is conducive to the normal operation of pavers, reduces the occurrence of paver malfunctions, lowers the usage cost of pavers, and extends the service life of pavers.

(1) Check the battery fluid level. If necessary, add some distilled water. The battery should be kept clean and dry.

(2) Check whether the levels of engine oil, fuel, coolant and hydraulic oil are sufficient; Check whether the quality of the hydraulic oil meets the requirements; otherwise, it will wear out the components of the hydraulic system. If necessary, it should be replenished or replaced in a timely manner.

(3) Clean or replace the filter elements of various filters.

Other maintenance work is the same as daily maintenance. Regular maintenance mainly focuses on the mandatory maintenance and replacement of worn parts.

Shutdown, storage and maintenance of the 4AP755 paver

For pavers that have been parked for more than one month, corresponding maintenance measures should be taken in accordance with the requirements specified in the user manual to ensure their normal and intact condition. It is conducive to the normal operation of the paver when it is used again and reduces the wear and tear of the paver during the parking period. First, the laying machine should be thoroughly cleaned and anti-rust treatment should be carried out. Only the basic components of the screed and the material distribution device can be placed on the main body of the paver. The extended parts should be removed and other accessories should be placed in a dry and well-ventilated room. The tracks should be supported with wooden blocks and the screed should be padded with wooden boards.

Then apply sufficient grease to all lubrication points and grease to all cylinders that cannot be retracted. Change the engine oil of the diesel engine and seal the intake and exhaust ports as well as the crankcase vent of the engine with plastic film and tape.

Remove the battery, charge it and store it in a dry and well-ventilated room. Charge it once a month. Every month, start the diesel engine and let it run for half an hour. Use the central grease pump to force the lubrication points of the entire machine to be lubricated (if there is no central grease pump, apply grease to the first lubrication point) until the old lubrication is squeezed out. Then, fill the central grease pump with grease. For diesel engines that have been parked for 6 to 12 months, after draining all the engine oil, add special storage oil to the diesel engine as per the instructions in the engine's user manual.