Concrete mixer truck Working principle of transport vehicle

With the rapid development of concrete production and construction technology, some countries have gradually adopted the mode of concrete centralized mixing and commercial supply, concrete is provided by a special concrete mixing station, and then transported to the construction site by the concrete mixing truck。This paper briefly introduces the structure principle and maintenance of concrete mixer truck。 　　1 Composition and working principle of concrete mixing transport vehicle 　　The concrete mixing transport vehicle is composed of an automobile chassis and a special device for concrete mixing transport。The chassis of concrete mixing transporters produced in our country mostly adopts the second type general chassis provided by vehicle manufacturers。The special mechanism mainly includes force extractor, stirring cylinder before and after support, reducer, hydraulic system, stirring cylinder, operating mechanism, cleaning system and so on。Its working principle: the power of the car chassis is taken out by the force taking device, and the variable pump of the hydraulic system is driven, the mechanical energy is converted into hydraulic energy to the quantitative motor, the motor drives the reducer, the reducer drives the mixing device, and the concrete is mixed。 　　1.1 Force taking device 　　The domestic concrete mixing transport truck adopts the force taking mode of the main vehicle engine。The function of the force taking device is to take out the power of the engine by controlling the force taking switch, and drive the mixing cylinder by the hydraulic system. The stirring cylinder is rotating in the feeding and transportation process to facilitate the feeding and mixing of the concrete. It is rotating in reverse when discharging, and the power connection with the engine is cut off after the end of the work。 1.2 Hydraulic System 　　The engine power taken out by the force extractor is converted into hydraulic energy (displacement and pressure), and then output into mechanical energy (speed and torque) by the motor to provide power for the rotation of the mixing cylinder。 　　1.3 Reducer 　　The speed output of the motor in the hydraulic system is decelerated and transmitted to the mixing cylinder。 　　1.4 Control mechanism 　　a.Control the rotation direction of the mixing drum, so that it is rotated in the feeding and transportation process, and in the discharge of the reverse rotation。 　　b.Control the speed of the mixing drum 　　1.5 Mixing device 　　It is mainly composed of a mixing cylinder and its auxiliary supporting parts。Mixing drum is a concrete loading container, it is made of high-quality wear-resistant thin steel plate, in order to automatically load and unload concrete, its inner wall is welded with special shape spiral blades。As the concrete rotates, it moves in the spiral direction of the blade, and is mixed and stirred during the continuous lifting and turning process。In the process of feeding and transportation, the mixing drum is turned and the concrete moves inward along the blade. When discharging, the mixing drum is reversed and the concrete is discharged outward along the blade。The rotation of the mixing cylinder is guaranteed by a hydraulic drive device。The loading capacity is 3 ~ 6 cubic meters。The concrete mixing truck is generally driven by the hydraulic pump driven by the automobile engine through the power output shaft, and then driven by the hydraulic motor driven by the high-pressure oil mixing cylinder, and the loading capacity of 9 to 12 cubic meters is driven by the on-board auxiliary diesel engine hydraulic pump to drive the hydraulic motor。Blade is the main component in the mixing device, damage or serious wear will lead to uneven concrete mixing。In addition, if the Angle of the blade is not designed reasonably, it will also make the concrete segregation。 　　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 mixing during transportation。The cleaning system also has a cooling effect on the hydraulic system。 　　2. Maintenance and repair of concrete mixing trucks 　　As a transportation vehicle, the concrete mixing truck must comply with the provisions of the Ministry of Communications Order No. 13 of 1990 in terms of maintenance and repair, and implement the maintenance and repair system of "regular testing, compulsory maintenance, and repair according to the situation"。Under this premise, combined with the actual situation of concrete mixing transport vehicles, do a good job of maintenance and repair。In terms of daily maintenance, in addition to the routine maintenance of the automobile engine, chassis and other parts, the concrete mixing truck must also do the following maintenance work。 　　2.1 Clean concrete storage tank (mixing cylinder) and inlet and outlet 　　Since concrete solidifies into hard blocks in a short time and is corrosive to steel and paint, washing the concrete adhered to the concrete tank and the inlet and outlet after each use of the concrete tank is a daily maintenance work that must be carefully carried out。These include: 　　a.Rinse the feed port with water before each loading to keep the feed port wet during loading; 　　b.Fill the cleaning water tank with water while loading; 　　c.After loading, wash the feed port and clean the remaining concrete near the feed port; 　　d.After unloading at the site, rinse the discharge tank, and then add 30-40 L of cleaning water to the concrete storage tank;Keep the concrete tank turning slowly in the forward direction when the vehicle is returning; 　　e.Remember to drain the sewage in the concrete tank before loading the next time; 　　f.Clean the concrete storage tank and around the inlet and outlet thoroughly every day after work to ensure that there is no cement and concrete agglomeration。 　　As long as the above work is not carried out seriously once, it will bring great trouble to the future work。 　　2.2 Maintaining the driver 　　The function of the driving device is to drive the concrete storage tank to rotate, which is composed of a force extractor, a cardan shaft, a hydraulic pump, a hydraulic motor, a control valve, a hydraulic oil tank and a cooling device。If this part stops working due to failure, the concrete storage tank will not be able to rotate, which will lead to the scrap of the concrete inside the car, and even make the whole tank of concrete condense in the tank, resulting in the scrap of the concrete mixing truck。Therefore, whether the driving device is reliable is a problem that must be attached great importance in use。In order to ensure the integrity and reliability of the drive device, the following maintenance work should be done: 　　a.The universal rotation part is the fault prone part, should be filled with grease on time, and often check the wear situation, timely repair and replacement。The team should have a spare cardan shaft assembly to ensure that it can resume work in tens of minutes in case of failure。 　　b.Keep hydraulic oil clean。The working environment of the concrete mixing truck is harsh, so it is necessary to prevent sewage and sediment from entering the hydraulic system。Hydraulic oil should be replaced regularly according to the requirements of the user manual。Once the hydraulic oil is found to be mixed with water or sediment during inspection, it is necessary to immediately stop the cleaning hydraulic system and replace the hydraulic oil。 　　c.Ensure that the hydraulic oil cooling unit is effective。It is necessary to regularly clean the hydraulic oil radiator, avoid the radiator being blocked by cement, check whether the radiator electric fan is running normally, and prevent the hydraulic oil temperature from exceeding the standard。As long as the hydraulic part ensures that the hydraulic oil is clean, the general failure is not much;But different manufacturers, the service life is not the same。 　　2.3 Pay attention to tire maintenance 　　In addition, our unit produces: oil tanker, sprinkler, suction truck, suction truck, fire truck, dump truck, van, garbage truck, coach, truck crane, road sweeper, aerial work truck, powder material truck, bulk cement transport truck, chemical liquid transport truck, cement mixing truck, etc。