2. Instruments and index signals should be correct and reliable. The bench board of electric concrete mixer should be supported by rubber sheet and dry board.

3. The transmission mechanism, working device, brake and all should be tightly fastened to ensure their normal operation.

4. Aggregate size should be within the tolerance range of the concrete mixer. Concrete mixer cannot handle the over-sized aggregate.

5. During empty operation, check the rotation direction of the mixing cylinder or mixing blades, operation of the working device and brake to ensure everything runs normally. Then, you can begin the feeding process.

6. During feeding process, forbid workers to put head or hands between the hopper and the rack. In operation, it is not allowed to put hands or tools into the mixing cylinder to move the materials or discharge the final products.

7. When the hopper lifts, people are forbidden to work or stand under it. Hopper should be equipped with hopper mat at the bottom of hopper pit. When cleaning the pit, the hopper must be fastened using chains.

8. Materials should be fed into the mixing cylinder in operation. When feeding new materials, you should discharge all the previous concrete in the mixing machine. You are not supposed to stop the machine midway or start the machine when there is a full load, unless the machine discharges by rotating anticlockwise.　

9. When the machine breaks down during operation, please cut off the power source immediately and get rid of the concrete in the mixing cylinder.

10. After operation, the mixing machine should be washed completely. If it is necessary for workers to do the washing in the mixing cylinder, please cut off the power first.