1.Improve the auxiliary seal: the shaft head protection ring B of this shaft structure and the side arm limit ring are relatively small in fixed surface and easy to fall off the mixing shaft.The direct consequence is that the mortar directly threatens the main seal and increases the probability of shaft end leakage.Therefore, it is necessary to improve its structure so that it is not easy to fall off, thus protecting the main seal.

2.Check the main seal regularly: if the main seal is working properly, the shaft end seal will not be broken, so it is important to ensure the normal operation of the main seal. Key to keep the main seal working properly:

①The yellow glue should be pressed tightly in time, to prevent it from loosening which will result in the clearance between it and the seal mounting ring becomes larger;

②The lubricating oil needs to be continuously squeezed from the clearance to the shell ,keep the oil flow smooth.

Both of these are indispensable.When the mixer is running,there is a big vibration which will cause the fixed steel frame of the yellow glue to be loose, so it is necessary to check whether the fixed screw rod is loose on the fixed steel frame. If it is loose, it should be tightened in time.Keep the oil way clear need to check whether there is oil leakage, if any it should be handled in time. Besides, after washing the mixer when the work is done, continue to pump lubricating oil to the fixed motion gap until it spills on the insides of the shell.If all the above can be done,the main seal will be well protected.

3.Increase the viscosity of lubricating oil: high viscosity lubricating oil has great resistance in the fixed motion gap, the automaton pump is used here, it can be realized by changing the type of the pump.

Therefore , the mixer user can prolong the service life of shaft end sealing device of the concrete mixer as following:  maintenance, servicing, timely adjust the fixed motion gap, and replace the sealing parts to avoid shaft end mortar leakage .

Attentions of concrete mixing plant in construction technology

1.The installation of concrete mixing plant should be carried out by professional personnel according to the instruction manuals, and it should be debugged under the leading of the technical personnel, after every technical performance indexes complied with the requirements and passed the acceptance, they it can be put into use.

2.The inspection items should meet the following requirements before the operation:

(1).The transmission parts , moving parts and aggregate hopper door, discharging door and track of the mixer and each supporting mechanism are not stuck；

(2).The oil level of each lubricating oil tank meet the requirement;

(3).Open valve to drain the excessive water from the air - water separator of the air control system, and open the drain plug of the air storage tank to drain the oil and water mixture;

(4).All the bolts have been fastened, each feeding and discharging valves are not over worn, the tension of each conveyor belt is appropriate and not deviation;

(5).All control and display parts of the weighing device is normal, and its accuracy is in accordance with the regulations;

(6).Each electrical device can effectively control the mechanical action , the contact point and the moving and static contact no obvious damage.

3.Prepare qualified sand and stone aggregate according to the technical performance of the concrete mixing plant , do not use those aggregate which size is beyond the suitable scope ;

4.Every part of the machine should be started gradually.After start-up, the operation of every parts and the indicating conditions of each instrument should be normal. The oil and air pressure should meet the requirements before starting the work.

5.During the operation, personnel are not allowed to enter the storage area;

6.Cover the mixer before starting.When the machine is running, it is strictly forbidden to put hands , legs into the hopper or mixer.

7.Do not shutdown when the mixer is full load mixing, when a failure or power failure occurs, cut off the power immediately,lock the switch box , and clean out the concrete in the mixer , then eliminate the failure or wait until the power supply is restored.

8.All machines of the concrete mixing plant should not overload operation;Check the operating conditions of the motor, if there is abnormal sound or the temperature is too high, shutdown immediately and check it .Do not operate when the voltage is too low.

9.Before the mixer(Twin shaft compulsory concrete mixer )stops, discharge the mixer  first, then turn off all the switches and pipelines in order. All the cement in the screw pipe should be conveyed out, and no material should be left in it.

10.After the operation, clean out the mixer ,the discharging door and the hopper, and flush them with water, the additive supply system also should be flushed.Clean out the blade and the blade holder of the weighing system , and ensure the weighing accuracy.

11.During the freezing season, the water in the water pump, the additive pump, the water tank and the additive box all should be drained , and start the water pump and the additive pump to run for 1 ~ 2min.

12.When the concrete mixing plant is transferred or discontinued, discharge all the materials in the water tank, the additive box, the cement、 sand and stone storage hopper , the weighing hopper ，then clean thoroughly.