A brief introduction to the principle of switching the concrete pump truck transfer case
The concrete pump truck was modified on the chassis of the truck. It is equipped with a motion and power transmission, a pumping and stirring device, a cloth device and other auxiliary devices on the chassis. The power of the concrete pump truck transmits the power of the engine to the hydraulic pump group or the rear axle through the power transfer box, and the hydraulic pump pushes the piston to drive the concrete pump to work. The concrete is then transported to a certain height and distance using the booms and ducts on the pump truck. In addition to driving the pump truck, the engine of the concrete pump truck is also used to drive the working device such as the pumping mechanism, the stirring mechanism and the distributing mechanism.
The power of each working device of the concrete pump truck comes from the automobile engine. When the concrete pump truck is working, the power of the automobile engine is transmitted to the transfer case through the gearbox, and then transferred to the hydraulic pump or the rear axle of the chassis through the transfer case. When the driver issues an instruction to switch to the pumping position, the pneumatic solenoid valve controls the cylinder on the transfer case to push the fork, and the fork pushes the split gear to switch to the pumping position, while cutting off the power to the rear axle, so that the car is at Parking status. Conversely, switch to the driving position.
2 failure phenomenon and failure analysis
Our company has a BSF36.09 pump truck produced by Putzmeister Machinery (Shanghai) Co., Ltd. Once the construction site is finished, when it is ready to be completed, the hydraulic system of the whole vehicle suddenly has no pressure failure. The output power of the box is in the driving position. When the driver issues a command to switch to the pumping position, the end of the fork lever can be retracted, but the separating gear in the transfer box does not leave the driving position, so the gear does not Will switch to the pumping position. Although the arm has been retracted, the three legs have been lifted, but the legs have not been fully recovered. The most troublesome problem is that there is also a front leg that is completely supported on the ground, with a weight of about 1/4 of the body pressed, and a force of nearly 10t is pressed against the leg. If the problem is not solved, even if the pump can drive, it cannot be returned to the company from the construction site.
3 pump car leg problem handling
The principle of the hydraulic system of the pump truck leg is analyzed. It is found that the hydraulic cylinder of each leg of the pump truck is protected by a two-way brake valve. Even if the oil supply pipe is removed, the hydraulic oil in the rodless cavity of the cylinder cannot be released, and the two-way system is The moving valve is connected to the rodless cavity inlet of the hydraulic cylinder, and cannot be disassembled without removing the two-way brake valve, so that the leg can not be recovered. Only in the two-way brake valve to find a way, the schematic diagram of the hydraulic system of the pump's outrigger is shown in Figure 1.
The two-way brake valve on the outrigger (the structure of the two-way brake valve is not detailed in the spare parts manual) has a large nut. The analysis two-way brake valve is composed of two controllable check valves. The nut is one of them, and people try to use a wrench to loosen the nut and hydraulic oil seeps out. When it was loose for three or four turns, the controllable check valve was ejected. Fortunately, the operator was prepared to hide the body without causing personal injury. Finally, the legs are taken up by a crowbar, etc., and they are reinforced with iron wires, and the other three legs are retracted and folded in a similar manner.
To sum up the experience of handling this fault, the jack should be lifted up by the jack, the oil pressure in the cylinder should be released, and then the two-way brake valve should be removed, so there is no danger.
4 method and process of repairing the transfer case
After stopping the pump truck, remove the forward and backward shafts of the transfer case. Use a chain hoist to hang the pump set with the main pump, remove the pump set, and remove the boom and outrigger pumps. After removing the transfer case and disassembling it, it was found that the fork of the copper alloy was broken. Schematic diagram of the transfer case structure is shown in Figure 2.
Contacting Putzmeister Machinery (Shanghai) Co., Ltd. to purchase the fork, the manufacturer can not provide the spot, can only be ordered to the German headquarters, and can only arrive in ten days. In order to solve the urgent need of the eyebrows, the research decided to use the brazing method to repair the broken fork. First, the broken end face is grouted with a grinder, the fork is welded by gas welding, and the excess solder is processed by the angle grinder. Then, the surface of the surface is treated well with sandpaper, etc. After the cleaning process, the machine is installed and the test is normal. This type of failure has not occurred for three years.
The concrete pump truck was modified on the chassis of the truck. It is equipped with a motion and power transmission, a pumping and stirring device, a cloth device and other auxiliary devices on the chassis. The power of the concrete pump truck transmits the power of the engine to the hydraulic pump group or the rear axle through the power transfer box, and the hydraulic pump pushes the piston to drive the concrete pump to work. The concrete is then transported to a certain height and distance using the booms and ducts on the pump truck. In addition to driving the pump truck, the engine of the concrete pump truck is also used to drive the working device such as the pumping mechanism, the stirring mechanism and the distributing mechanism.
The power of each working device of the concrete pump truck comes from the automobile engine. When the concrete pump truck is working, the power of the automobile engine is transmitted to the transfer case through the gearbox, and then transferred to the hydraulic pump or the rear axle of the chassis through the transfer case. When the driver issues an instruction to switch to the pumping position, the pneumatic solenoid valve controls the cylinder on the transfer case to push the fork, and the fork pushes the split gear to switch to the pumping position, while cutting off the power to the rear axle, so that the car is at Parking status. Conversely, switch to the driving position.
2 failure phenomenon and failure analysis
Our company has a BSF36.09 pump truck produced by Putzmeister Machinery (Shanghai) Co., Ltd. Once the construction site is finished, when it is ready to be completed, the hydraulic system of the whole vehicle suddenly has no pressure failure. The output power of the box is in the driving position. When the driver issues a command to switch to the pumping position, the end of the fork lever can be retracted, but the separating gear in the transfer box does not leave the driving position, so the gear does not Will switch to the pumping position. Although the arm has been retracted, the three legs have been lifted, but the legs have not been fully recovered. The most troublesome problem is that there is also a front leg that is completely supported on the ground, with a weight of about 1/4 of the body pressed, and a force of nearly 10t is pressed against the leg. If the problem is not solved, even if the pump can drive, it cannot be returned to the company from the construction site.
3 pump car leg problem handling
The principle of the hydraulic system of the pump truck leg is analyzed. It is found that the hydraulic cylinder of each leg of the pump truck is protected by a two-way brake valve. Even if the oil supply pipe is removed, the hydraulic oil in the rodless cavity of the cylinder cannot be released, and the two-way system is The moving valve is connected to the rodless cavity inlet of the hydraulic cylinder, and cannot be disassembled without removing the two-way brake valve, so that the leg can not be recovered. Only in the two-way brake valve to find a way, the schematic diagram of the hydraulic system of the pump's outrigger is shown in Figure 1.
The two-way brake valve on the outrigger (the structure of the two-way brake valve is not detailed in the spare parts manual) has a large nut. The analysis two-way brake valve is composed of two controllable check valves. The nut is one of them, and people try to use a wrench to loosen the nut and hydraulic oil seeps out. When it was loose for three or four turns, the controllable check valve was ejected. Fortunately, the operator was prepared to hide the body without causing personal injury. Finally, the legs are taken up by a crowbar, etc., and they are reinforced with iron wires, and the other three legs are retracted and folded in a similar manner.
To sum up the experience of handling this fault, the jack should be lifted up by the jack, the oil pressure in the cylinder should be released, and then the two-way brake valve should be removed, so there is no danger.
4 method and process of repairing the transfer case
After stopping the pump truck, remove the forward and backward shafts of the transfer case. Use a chain hoist to hang the pump set with the main pump, remove the pump set, and remove the boom and outrigger pumps. After removing the transfer case and disassembling it, it was found that the fork of the copper alloy was broken. Schematic diagram of the transfer case structure is shown in Figure 2.
Contacting Putzmeister Machinery (Shanghai) Co., Ltd. to purchase the fork, the manufacturer can not provide the spot, can only be ordered to the German headquarters, and can only arrive in ten days. In order to solve the urgent need of the eyebrows, the research decided to use the brazing method to repair the broken fork. First, the broken end face is grouted with a grinder, the fork is welded by gas welding, and the excess solder is processed by the angle grinder. Then, the surface of the surface is treated well with sandpaper, etc. After the cleaning process, the machine is installed and the test is normal. This type of failure has not occurred for three years.
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