Working principle of concrete mixer truck
With the rapid development of concrete production and construction technology, some countries have gradually adopted the method of centralized concrete mixing and commercial supply. Concrete is provided by special concrete mixing stations and then transported by concrete mixing trucks to various construction sites. The structure principle and maintenance of concrete mixer truck are briefly introduced.
1 Composition and working principle of concrete mixer truck Concrete mixer truck is composed of automobile chassis and special device for concrete mixer transportation. The chassis of concrete mixer trucks produced in China mostly use the second-class general chassis provided by the vehicle manufacturers. Its special mechanisms mainly include power take-off, front and rear brackets of the mixing drum, reducer, hydraulic system, mixing drum, operating mechanism, cleaning system, etc. Its working principle: Take out the power of the car chassis through a power take-off device, and drive the variable pump of the hydraulic system, convert the mechanical energy into hydraulic energy and send it to the fixed-quantity motor. Stir.
1.1 Power take-off device The domestic concrete mixer truck adopts the power take-off method of the main vehicle engine. The function of the power take-off device is to take out the engine power by operating the power take-off switch, and drive the mixing drum through the hydraulic system. The shaking drum rotates forward during the feeding and transportation process to facilitate the feeding and mixing of the concrete. Reverse rotation, cut off the power connection to the engine after the end of work.
1.2 The hydraulic system converts the engine power taken through the power take-off into hydraulic energy (displacement and pressure), and then outputs the mechanical energy (speed and torque) through the motor to provide power for the rotation of the mixer.
1.3 The reducer reduces the speed of the motor output in the hydraulic system and transmits it to the mixing drum.
1.4 Operating mechanism a. Control the rotation direction of the mixing drum, so that it rotates forward during feeding and transportation, and reverses when discharging.
b. Control the rotation speed of the mixing drum 1.5 Mixing device It mainly consists of the mixing drum and its auxiliary supporting parts. The mixing drum is a concrete loading container. It is made of high-quality wear-resistant thin steel plate. In order to be able to load and unload concrete automatically, its inner wall is welded with special shaped spiral blades. When rotating, the concrete moves in the spiral direction of the blade and is mixed and stirred during the continuous lifting and turning process. During the feeding and transportation process, the mixing drum rotates forward, and the concrete moves inward along the blade. When discharging, the mixing drum reverses, and the concrete is discharged outward along the blade. The rotation of the mixer is ensured by the hydraulic drive. Concrete mixing trucks with a loading capacity of 3 to 6 cubic meters generally use a hydraulic pump driven by a car engine through a power output shaft, and then a hydraulic motor driven by a high-pressure oil to drive the mixing drum. For a loading capacity of 9 to 12 cubic meters, the vehicle-mounted auxiliary diesel engine The hydraulic pump drives a hydraulic motor. The blade is the main part of the mixing device. Damage or severe wear will cause uneven mixing of the concrete. In addition, if the angle of the blade is not designed properly, the concrete will also segregate.
1.6 Cleaning System The main function of the cleaning system is to clean the mixing drum, and sometimes it is also used for dry material stirring during transportation. The cleaning system also cools the hydraulic system.
2 Maintenance and repair of concrete mixer trucks As a transportation vehicle, concrete mixer trucks must comply with the provisions of the Ministry of Communications Decree No. 13 of 1990 and perform the maintenance and repair of "periodic inspection, compulsory maintenance, and conditional repairs" system. Under this premise, combined with the actual situation of the concrete mixer truck, do maintenance and repair. In terms of daily maintenance, in addition to the conventional maintenance of automobile engines, chassis and other parts, concrete mixer trucks must also do the following maintenance work.
2.1 Cleaning the concrete storage tank (mixing cylinder) and the inlet and outlet because the concrete will solidify into a hard mass in a short time and it is corrosive to steel and paint, so after each use of the concrete storage tank, wash and adhere The concrete on the concrete storage tank and the inlet and outlet is a daily work that must be carried out carefully. These include:
a. Rinse the feeding port with water before each loading to keep the feeding port moist while charging;
b. Fill the washing water tank that comes with the car with water while loading;
c. After loading, rinse the inlet and clean the residual concrete near the inlet;
d. After unloading at the construction site, flush the discharge tank, and then add 30-40 L of washing water to the concrete storage tank; keep the concrete storage tank turning slowly at the forward speed when the vehicle returns;
e. Remember to discharge the sewage in the concrete storage tank before the next loading;
f. Clean the concrete storage tank and the surroundings of the inlet and outlet at the end of each day to ensure that cement and concrete agglomeration are not adhered.
As long as the above work is not carried out once, it will bring great trouble to the future work.
2.2 Maintenance drive device The drive device is used to drive the concrete storage tank to rotate. It consists of power take-off, cardan shaft, hydraulic pump, hydraulic motor, control valve, hydraulic oil tank and cooling device. If this part stops working due to a failure, the concrete storage tank will not be able to rotate, which will cause the concrete in the car to be scrapped, and even the whole tank of concrete to be condensed in the tank, causing the concrete mixer truck to be scrapped. Therefore, whether the driving device is reliable or not is a problem that must be taken seriously in use. To ensure the integrity and reliability of the drive unit, the following maintenance work should be done:
a. The universal rotating part is a frequently-occurring part. Grease should be added on time, and the wear condition should be checked frequently, and repaired and replaced in time. The fleet should have a spare cardan shaft assembly to ensure that it can resume work within tens of minutes in the event of a failure.
b. Keep the hydraulic oil clean. The concrete mixer truck has a bad working environment, and it is necessary to prevent dirty cement and sand from entering the hydraulic system. The hydraulic oil should be replaced regularly as required in the instruction manual. Once water or sediment is found in the hydraulic oil during inspection, the hydraulic system must be shut down immediately to clean the hydraulic system and replace the hydraulic oil.
c. Ensure that the hydraulic oil cooling device is effective. Clean the hydraulic oil radiator regularly to prevent the radiator from being blocked by cement, check whether the radiator electric fan is operating normally, and prevent the hydraulic oil temperature from exceeding the standard. As long as the hydraulic part ensures that the hydraulic oil is clean, there are usually not many failures; however, the service life is different for different manufacturers.
2.3 Pay attention to the maintenance of tires. In addition, our unit produces: tanker trucks, sprinkler trucks, manure suction trucks, sewage suction trucks, dump trucks, vans, garbage trucks, coach trucks, truck cranes, aerial work trucks, powder pellets Material bulk cement transporter, chemical liquid transporter, cement mixer, etc.