Railway engineering equipment_ Hydraulic system failure of traveling clutch of screen cleaner
Railway engineering equipment_ Hydraulic system failure of traveling clutch of screen cleaner
RM80 screen cleaner is a large road maintenance machine imported from abroad. After 15 years of use, the equipment tends to be aging and the failure rate increases, which has a great impact on the safety and punctuality of overhaul construction.
(1) Working principle of hydraulic system of running clutch
The running of the screen cleaner is divided into interval (high-speed) running and operation (low-speed) running. These actions are controlled by the hydraulic clutch in the axle gearbox. Each axle has two groups of hydraulic clutches, which are respectively responsible for interval running and operation running, as shown in Figure E. The pressure oil output from the assembly enters the Ag and FG clutches through the hydraulic three position four-way directional valve. AG is the operation (low-speed) traveling clutch, FG is the interval traveling (high-speed) clutch, the hydraulic motor pump assembly and the Ag and FG clutches form a clutch driving mechanism, each shaft has a clutch driving mechanism, and the whole screen cleaner has four clutch driving mechanisms.
The hydraulic motor pump components of axle 1 and axle 2 on the front bogie are connected in series, share a driving hydraulic circuit and are driven by a hydraulic pump. The hydraulic motor pump components of axle 3 and axle 4 on the rear bogie are also connected in series and driven by one hydraulic pump (axle 1 ~ axle 4 are not shown in the figure).
(2) Common fault phenomena
The failure of the hydraulic system of the traveling clutch is manifested in the "axial pressure" of the clutch. "Axle pressure" of clutch refers to the pressure of Ag and FG of 1, 2, 3 and 4 axle clutches. Normally, the overflow valve is set to 15MPa and the pressure switch is set to 12MPa. When it is lower than 12MPa, the friction plates of Ag and FG clutch will slip and burn. The fault phenomena mainly include low shaft pressure, unstable pressure, inconsistent pressure between Ag and FG clutch, AG has pressure but FG has no pressure, AG has no pressure but FG has pressure, Ag and FG have no pressure at the same time, etc.
(3) Maintenance method
To repair such faults, first confirm whether the oil level of the hydraulic oil tank is correct, whether the oil quality is good, whether the engine speed is normal (2150r / min) and whether the control pressure is normal (6Mpa).
① Low or unstable shaft pressure means that the pressure of Ag and FG clutches is lower than 12MPa, resulting in sliding and damage to the friction plates of Ag and FG clutches. The RM80 screen cleaner is equipped with a protection circuit. When the axial pressure is lower than 12MPa, the screen cleaner does not run. The maintenance steps are as follows.
a. Adjust the pressure of the overflow valve. When the pressure is higher than 12MPa, the adjustment will not work. Proceed to the next step.
b. Check whether it is flexible to push by hand. If it is not flexible, replace or repair it.
c. Check the shift clutch and the sealing ring on the axle gearbox 2 shaft. If worn, replace it.
d. Check the hydraulic motor pump assembly and connecting nylon sleeve (internal spline). If it is damaged or worn, replace it.
e. Check various parameters of the motor and pump in the hydraulic motor pump assembly (on the test bench), adjust the parameters or replace the damaged motor and pump.
f. Check the hydraulic pump parameters, adjust the parameters or replace the damaged pump.
② AG and FG clutch pressures are inconsistent (one of them is normal)
a. Check whether the hydraulic reversing valve is flexible. If not, repair or replace it.
b. Check the condition of the sealing ring of axle gearbox 2 and replace the worn sealing ring.
c. Check the sealing rings of Ag and FG clutches and replace the worn sealing rings.
③ AG has pressure, FG has no pressure; AG has no pressure, FG has pressure
a. Check whether the hydraulic directional valve is flexible. If not, repair or replace it.
b. Check the sealing ring of axle gearbox 2 and replace the worn sealing ring.
④ AG and FG clutches have no pressure at the same time
a. Check the amount of lubricating oil in the axle gearbox. If it is insufficient, add lubricating oil.
b. Check the sealing ring of axle gearbox 2 and replace the worn sealing ring.
c. Check the internal spline of connecting nylon sleeve of motor pump assembly and replace the damaged nylon sleeve.
d. Check the hydraulic directional valve and repair or replace it.
e. Check various parameters of the motor and pump in the motor pump assembly (on the test bench), adjust the parameters or replace the damaged motor and pump.
f. Check the hydraulic pump shaft. If it is broken, replace it with a new one.
g. Check the hydraulic pump parameters, adjust the parameters or replace the damaged pump.
(4) Troubleshooting example
① During the construction of RM80 screen cleaner, there is no pressure on axis 1 and 2, and the axial pressure on axis 3 and 4 is normal. Analysis: there is no pressure on shaft 1 and 2 at the same time, indicating that there is no pressure oil input at the common input end of the motor pump assembly. Disassemble and inspect the drive pump and find that the pump shaft is broken. After replacing the pump shaft, start the engine and the shaft pressure is normal.
② There is no pressure on the Ag and FG clutches of the 3rd shaft of RM80 screen cleaner, and the pressure of the 4th shaft is normal. Analysis: there is no pressure in the 3-axis Ag and FG clutches, indicating that there is a problem in their common oil circuit; The normal pressure of 4-axis Ag and FG indicates that the driving hydraulic pump works normally. Remove the oil outlet pipeline of the pump in the 3-axis motor pump assembly, start the engine and find that there is no pressure oil output, so the problem is likely to be caused by the motor pump assembly. Disassemble and inspect the motor pump assembly. It is found that the internal spline nylon sleeve used for the connection between the motor and the pump is worn. Re process the internal spline sleeve. After reassembly, start the engine and the pressure of shaft 3 returns to normal.
③ During the operation of RM80 screen cleaner, the Ag pressure of 4-axis operation disappears, while the FG pressure is normal during interval operation, and the Ag and FG pressures of 1, 2 and 3 axes are normal. Analysis: the pressure of the running FG clutch in the section is 15MPa, which indicates that the driving hydraulic pump motor pump assembly works normally, but there is leakage in the Ag control oil circuit. Overhaul the control oil circuit at the Ag and FG shaft ends of the axle gearbox. It is found that the sealing ring in the sealing oil chamber of the Ag clutch is damaged. After replacing the sealing ring, start the engine and the Ag pressure returns to normal.
