Correct use of the hottest concrete mixer truck

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The correct use of concrete mixer truck

concrete mixer truck is produced and developed with the production of commercial concrete. Although the concrete mixer truck in China has been developed for more than 30 years, its speed is very slow, and its large-scale use is a matter of recent years. The Tenth Five Year Plan for the development of bulk cement issued by the State Economic and Trade Commission in 2001 clearly requires that large and medium-sized cities prohibit mixing concrete on site in urban areas on December 31, 2003, and other cities prohibit mixing concrete on site in urban areas from December 31, 2005. The introduction of this policy has greatly driven the demand and development of commercial concrete, and the demand for concrete mixer trucks, as the ideal transportation equipment of commercial concrete, has also begun to increase year by year

due to the short time of large-scale use of concrete mixer trucks, many users do not know much about some daily use and maintenance, and the working environment of mixer trucks is relatively poor, which has caused some unnecessary failures and economic losses. This article talks about some views on the use and maintenance requirements of mixer trucks, hoping to be helpful to the daily use of the majority of mixer truck users

1 use of hydraulic transmission system

in each system of concrete mixer truck, the hydraulic system is the most important and delicate working part, especially for its use and maintenance. The hydraulic motors, hydraulic oil pumps and reducers used in mixer trucks produced by domestic manufacturers are mostly imported parts with original packaging, and the typical configuration is shown in Table 1

the working principle of the hydraulic system of the concrete mixer truck is shown in Figure 1. When the variable lever is turned to the left by the control device, the oil pump starts to drain oil from port a, enters the motor through the high-pressure oil pipe, the motor rotates, the oil flowing through the motor becomes low-pressure oil, and flows back to the oil pump from port B through another high-pressure oil pipe. The larger the rotation angle of the variable lever, the more oil is discharged by the oil pump per revolution, and the higher the speed of the motor. When the variable rod is operated to rotate to the right, the pressure oil is discharged from port B, the rotation direction of the motor changes, the low-pressure oil flows back from port a, and the high-pressure oil pump supplies oil to the oil cylinder to make the piston rise up the oil pump. The rotation of the motor drives the reducer, so that the mixing drum of the mixer can be steplessly variable within a certain speed range and has two rotation directions. The principle of other hydraulic systems is the same

to make the hydraulic system work efficiently and trouble free, it is necessary to strengthen the maintenance in daily use, operate in strict accordance with the requirements of the manual, and replace the hydraulic oil and auxiliary devices (mainly filters) in time as required. Pay attention to the following points during oil change

1) use hydraulic oil whose performance parameters meet the requirements, and never use hydraulic oil that has been used or has been filtered and precipitated

2) it is best to use an oil filter with a filtration accuracy of 10 when refueling

3) the shells of the main system, pump and motor should be filled with hydraulic oil before starting

4) the hydraulic oil and filter element must be replaced every 500 hours and every 2000h after the first use of the user. The hydraulic oil and filter element recommended in the manual must be used

at the end of December 2004, a user in Yantai area filled a very small amount of water in the hydraulic oil during the oil change of the mixer truck, resulting in the failure of the mixing drum of the mixer truck under the low temperature in winter. When he drove the mixer truck to our company for maintenance (it took about 1H on the road), the mixing drum of the mixer truck could operate normally again. This is mainly because the valve port is blocked by water freezing in the oil pump. After a long time of driving, the ice in the pump melts and the pump can work normally again. After we replaced all the hydraulic oil of this car, the above problems did not occur again. It can be seen that the added hydraulic oil must ensure its quality, otherwise it will cause unnecessary faults and economic losses

good maintenance is a powerful guarantee for the reliable operation of the hydraulic system. Users should pay attention to the working condition of the hydraulic system in daily use, and stop the machine for inspection in time in case of any abnormality. Don't be careless and cause greater losses

2 use of supporting roller

supporting roller is one of the main load-bearing parts of the mixing truck. The weight of the mixing drum and the concrete in it is mainly supported by the supporting roller and reducer. At the same time, due to the limitations of the site road conditions, the force it bears is uneven and impact. Therefore, it is necessary to limit the jumping of the mixing drum to reduce the impact on the supporting roller. There are two forms of current models: one is to add a strap to pull the mixing drum; The second is to add a stop at the rear upper end of the mixer truck support. No matter which form, care should be taken in daily use, and the damaged ones should be replaced and repaired in time to avoid adverse impact on the service life of the supporting wheel. When using, pay special attention to adding grease to the bearing of the supporting roller, and at the same time, add grease to the supporting roller. In daily work, the author presses the "take out" button to take out the pendulum, and the damage of the supporting wheel encountered in the process of taking out the pendulum is mostly caused by the bearing damage caused by the failure to fill the grease in time. At the same time, pay attention to whether the locking nut is loose. If it is loose, tighten it in time, otherwise it will damage the supporting roller bearing and cause unnecessary losses

3 the problem of uneven discharge

the problem of uniformity of discharge is one of the important indicators of mixer performance, which directly affects the project quality. When transporting concrete, the rotating speed of the mixing drum should be controlled at 2~5r/min, and the total number of revolutions of the mixing drum should be controlled within 300 revolutions. If the transportation distance of concrete is long or the slump is large, rotate the mixing drum quickly for 5~10 revolutions before discharging, so that the concrete inside can be fully mixed, so that the uniformity of discharging will be greatly improved. If the concrete loses water on the way, water should be added to the construction site for adjustment and full mixing. Of course, this situation should be avoided as much as possible, because it will make the quality of concrete out of control. Some users do not pay attention to controlling the rotation speed during transportation, too fast will increase fuel consumption, and too small will cause concrete segregation. Therefore, the rotating speed of the mixing drum should be strictly controlled according to the requirements in order to improve the efficiency

4 use of transmission shaft

the working environment of concrete mixer truck is relatively bad, so pay attention to adding grease to the transmission shaft during use. In the process of repairing the mixer truck, we have received many feedback from the user that the country is expected to become the largest plastic flexible packaging consumer market in the Middle East and Africa. The transmission shaft was damaged in a short time, or the whole transmission shaft was scrapped. During the inspection, it was found that this situation was mostly caused by the damage caused by the user's inattention to fill the transmission shaft with grease in time. If the lubricating grease is not filled in time, the cross shaft of the transmission shaft will be subject to dry friction, and the cross shaft will be scrapped after a short time, thus resulting in the scrapping of the whole transmission shaft

5 handling of faulty vehicles

the author once encountered such an example: the mixer engine of a user in Dongying failed and could not be started normally. Because he only paid attention to the maintenance of the engine and ignored the solidification of the concrete in the mixing drum, the concrete solidified in the mixing drum and the mixing drum was scrapped, resulting in a loss of more than 20000 yuan. In fact, when the mixer truck breaks down, the priority should be how to discharge the concrete in the mixing drum as soon as possible, and then how to repair it. Generally, there are two conditions that cause the mixing drum of the mixer truck not to rotate: (1) hydraulic system or engine failure; (2) The motor has failed. The treatment method is as follows

1) treatment of hydraulic system or engine failure:

(1) open the mixing drum manhole cover, unscrew the pipe joint of the high-pressure hose on the motor, rotate the mixing drum so that the mixing drum manhole is inclined downward, and discharge the concrete from the mixing drum manhole

(2) remove the high-pressure hose of the faulty vehicle from the motor, connect the high-pressure hose for rescue, connect the other end to the oil pump of the rescue vehicle, connect one end of the emergency oil return pipe to the motor oil drain port of the faulty vehicle, and connect the other end of the oil return pipe to the oil return port of the oil pump of the rescue vehicle. Use the rescue vehicle to control the rotation of the mixing drum of the faulty vehicle and discharge the concrete

after on-site testing, we found that under the condition that all the tools in the manufacturer are complete, it takes about 1h to adopt the second method, and the time on the site may be longer, so it is recommended to adopt the first method to discharge the concrete

2) in case of motor failure, the treatment is relatively simple. Remove the motor of the rescue vehicle and install it on the failed vehicle, then connect each oil pipe, and start the rescue vehicle to discharge the concrete in the mixing drum

in short, for the mixer truck, when there is a fault, we should timely judge the cause of the fault, and take effective measures to discharge the concrete in the mixing drum before solving the fault

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