Maintenance Of The Pumping Unit--Concrete Pump Truck Maintenance And Servicing (Part 2)

Concrete Pump Truck Maintenance and Servicing (Part 2)

1.3 Maintenance of the pumping unit

1. Fill the lubricating oil tank and all lubrication points with grease each shift, and fill the water tank with clean water.

2. Check the functionality of all electrical components each shift.

3. Check the pump reversing valve, distribution valve swing, and the forward and reverse rotation of the mixing device each shift to ensure they operate normally.

4. After pumping approximately 2000 m³ of concrete, check the gap between the spectacle plate and the cutting ring. If it exceeds 2 mm and the wear is uniform, consider adjusting the gap. The adjustment steps are shown in Figure 1-1 below:

Figure 1-1 

1) Clean the hopper and S-tube valve thoroughly;

2) Unscrew the anti-rotation screw 4;

3) Tighten the irregular bolt 5 and pull the S-tube toward the rear wall of the hopper to reduce the gap between the cutting ring and the spectacle plate;

4) Tighten the anti-rotation screw 4.

5. Replacement of the cutting ring

1) Turn off the engine and release the pressure in the accumulator. Remove the hopper screen.

2) Loosen the irregular bolts shown in the diagram by 20mm. Do not loosen them too much. Otherwise, when the "S" tube retracts, the bearing fitting will disengage from the bearing sleeve, damaging the seal and preventing it from sealing the mortar, thus affecting the service life of the "S" tube.

3) Remove the outlet flange and pry the "S" tube towards the outlet to make the gap between the cutting ring and the spectacle plate approximately 20mm. Remove the cutting ring.

4) Check if the installed rubber spring is damaged. If damaged, replace it.

5) Conversely, install a new cutting ring.

6. Replacement of the spectacle plate

1) Repeat the cutting ring replacement process.

2) Unscrew all the mounting bolts of the spectacle plate; a slight vibration will allow the spectacle plate to be removed.

3) Install the new spectacle plate.

7. During each shift, check the wear of the S-tube and its bearings, as well as the wear of the mixing device, mixing blades, and mixing bearings. If excessive wear is found, replacement is required. Refer to this manual for specific replacement methods.

8. During each shift, check that the concrete piston is properly sealed and that no mortar has seeped into the water tank. If excessive concrete slurry is found in the water tank, check if the concrete piston needs replacement; replace it if necessary. The specific steps for replacing the concrete piston are as follows:

1) Open the water tank cap on the water tank, as shown in Figure 1-2.

2) Lift the pressure plates and remove the positioning sleeves under low-pressure pumping conditions, as shown in Figure 1-3.

3) Close the ball valve in the U-shaped pipe at the tail of the pump cylinder.

4) After the concrete piston is fully pushed out of the main cylinder by jogging, stop the machine first, then operate the main cylinder jog switch to reduce the pumping and distribution pressure gauges to zero. The concrete piston can only be disassembled after the machine has been completely depressurized while stopped!

5) Remove the bolts connecting the concrete piston and the connecting flange, as shown in Figure 1-4.

6) Remove the concrete piston, as shown in Figure 1-5.

4. When installing a new piston, apply grease between the two lips of the new piston.

5. When pushing the concrete piston into the concrete cylinder, the speed must be slow, and only a jogging motion can be used.

9. Quick-change piston principle and operating procedures

1) "Quick-change piston" configuration recognition

Attention: The term "quick-change piston" as used here refers only to pump trucks with a "quick-change cylinder" added to the tail of the pumping cylinder.

Pump trucks equipped with a "quick-change piston" function have a "quick-change cylinder" added to the tail of the pumping cylinder; a "quick-change piston" button is added to the control panel.

2) Principle of "quick-change piston"

A "quick-change cylinder" is added to the tail of the pumping cylinder, replacing the positioning sleeve in the water tank. When changing the concrete piston, the removal of the positioning sleeve is eliminated, thus achieving quick piston replacement.

During normal pumping, the solenoid valve is de-energized and in the left position, the "quick-change cylinder" extends, and the stroke of the pumping cylinder decreases, restricting the concrete piston from exiting the concrete cylinder. When changing the piston, the solenoid valve is energized and in the right position, the "quick-change cylinder" retracts, the stroke of the pumping cylinder increases, and the concrete piston can exit the concrete cylinder.

3) Precautions for using the "quick-change piston"

When replacing the piston or when the piston needs to be returned to the water tank, the "quick-change piston" switch should be turned to the "On" position;

After the piston replacement or other operations are completed and the piston is returned to the concrete cylinder, the "quick-change piston" switch should be switched to the "Off" position.

Attention:

After the "quick-change piston" switch is turned to the "Off" position, the "quick-change cylinder" oil replenishment operation should be performed immediately. During the oil replenishment process, the water tank proximity switch seat must be removed and the pump cylinder ball valve must be in the open position;

"Quick-change cylinder" oil replenishment operation: At an engine speed of 1400 r/min or higher and a pumping gear of 2-4, jog the pump cylinder and hold it for 30-60 seconds. Repeat the jogging and holding operation twice for each of the left and right pump cylinders.

 

10. For the new quick-change pumping cylinder, the concrete piston replacement procedure is as follows:

1) Remove the water tank cover, as shown in Figure 1-6.

2) Close the ball valve in the U-shaped pipeline at the tail of the pump cylinder.

3) Turn the selector switch to "ON", as shown in Figure 1-7.

4) After the concrete piston has fully extended out of the main hydraulic cylinder, stop the machine first, Then operate the main cylinder jog switch to reduce the pumping and distribution pressure gauges to zero.

Attention: The concrete piston can only be disassembled and installed after the machine has been completely depressurized while it is stopped!

5) Remove the bolts connecting the concrete piston and the connecting flange, as shown in Figure 1-8.

6) Remove the concrete piston, as shown in Figure 1-9.

7) The steps for installing the concrete piston are the reverse of the steps above.

8) Before starting automatic pumping or automatic reverse pumping, the selector switch must be turned to the "OFF" position, as shown in Figure 1-10.

Attention: 

1. Install the concrete piston and connecting flange respectively.

2. Stop the machine and empty the concrete from the hopper and concrete cylinder.

3. When installing a new piston, grease should be applied between the two lips of the new piston.

4. When pushing the concrete piston into the concrete cylinder, the speed must be slow, and only a jogging motion can be used.

 

11. For the new quick-change pumping cylinder without a U-shaped pipeline and ball valve at the tail end, the specific replacement of the concrete piston is as follows:

1) Open the water tank cover, as shown in Figure 1-11.

2) Under low-pressure pumping conditions, lift the pressure plates and remove the positioning sleeves, as shown in Figure 1-12.

3) Move the "Quick-Change Piston" switch to the "Jog" position and the "High/Low Pressure" switch to the "Low Pressure" position, as shown in Figure 1-13.

4) Under low pressure, jog the main cylinder until the concrete piston is completely withdrawn from the cylinder. Then, stop the machine and operate the main cylinder jog switch to reduce the pumping and distribution pressure gauges to zero. The concrete piston can only be disassembled after the machine has been completely depressurized while stopped.

Attention: The concrete piston can only be disassembled and installed after the machine has been completely depressurized while it is stopped!

5) Remove the bolts connecting the concrete piston and the connecting flange, as shown in Figure 1-14.

6) Remove the concrete piston, as shown in Figure 1-15.

7) The steps for installing the concrete piston are the reverse of the steps above.

8) Before starting automatic pumping or automatic reverse pumping, the "piston quick change" switch must be turned to the "off" position, as shown in Figure 1-16.

 

Attention: