When the ZL40 loader hydraulic transmission system works, the gear pump inhaled the low pressure oil through the filter net from the oil pan, and the high pressure oil pumped through the filter is filtered into the variable speed distribution valve. When the system is set up pressure (pressure exceeds 1.1MPa), the pressure regulating valve is divided into two roads, one of which is under 1.1 - 1.3MPa pressure through the shutoff valve to the retaining distribution valve, and then into the different working hydraulic cylinders according to the work needs to realize I, II, or reverse gear; the other is supplied by the relief valve to the torque converter with the force of 0.57MPa. It is proved that the oil pressure and flow in the torque converter flow out of the low-pressure oil after heat dissipation by the torque converter and lubricate the overrunning clutch and gears through the back pressure valve.
Generally speaking, the hydraulic transmission system of ZL40 loader will have various faults one after another after using 3000 hours, and all of them have certain external performance. Starting from the external characteristics of the aircraft, the causes and troubleshooting methods of the system are analyzed.
1. Faults found on the hydraulic pressure gauge
(1) the swing of the pressure gauge pointer
The pressure gauge oscillating under the pressure of all gears indicates the air entering the oil path. At this time, the connection between the oil pump and the oil can be locked and the oil pipe can be eliminated.
(2) the pressure of each shift deviates from the normal value
(1) the pressure gauge is low (lower than 0.8MPa). The possible reasons are the severe burn of the gear pump, low efficiency, severe burn of the gear pump, low efficiency, the loss of elasticity of the pressure regulating spring of the transmission valve, the break of the spring seat, the death of the valve stem or the energy storage piston, and the inability to compress the pressure regulating spring; cut off The valve stem card is dead in the cutting position; the oil bottom shell filter net is seriously blocked, resulting in the shortage of oil supply; the sealing ring inside the seal of the variable speed distribution valve accumulator is damaged and the high and low pressure chamber is colluded.
(2) the pressure of I and reverse gear is normal, and the pressure of the second gear is low
The possible reasons are the damage or leakage of the sealing ring of the second retaining oil hole in the combination of the end cover and the box body (accompanied by oil leakage), and the leakage of the rotating oil seal at the joint between the middle part of the end cover and the hydraulic cylinder of the second gear, and the drop off of the piston guide pin, so that the high pressure cavity is colluded.
(3) the pressure of the second gear and the reverse gear is normal, and the pressure of the first gear is low
The possible reasons are as follows: the rectangular seal ring at the joint of the hydraulic cylinder and the cylinder body is damaged or missed; the piston oil seal of the first gear is damaged or the cylinder body has sand holes.
(4) the pressure of I and II gears is normal and the pressure of reverse gear is low
The possible reasons are as follows: the box wall is cracked in the reverse gear position, the reverse gear piston seal ring is damaged, the gearshift valve seal ring is damaged, and the gearshift valve seal ring is damaged.
(I) the first stop and the reverse pressure do not go up, and the second gear pressure is normal.
The possible reasons are as follows: the connecting bolt between the middle cover and the box is broken; the clearance between the middle cover and the first block hydraulic cylinder is not controlled between 0.3 and 0.4 mm.
2. Faults found in hydraulic oil
(1) a large number of aluminum chips are contained in the oil
It shows that the working wheels of the torque converter wear out each other, so the transmission efficiency is reduced and the working oil is heated. Check the torque converter and find out the wearing parts. Replace the bearing when necessary, and tighten the first level turbine cover.
(2) a large amount of copper chips are contained in the oil
It indicates dry grinding or skidding between main and driven friction sheets. Check whether the injection of hydraulic oil is in place; check the pressure of the hydraulic pump is normal, if the pressure is normal, it is the improper assembly or deformation of the main, driven friction plate and should be removed and replaced.
(3) the oil contains a large amount of iron chips
It shows that the overrunning clutch is skidding; at this time, the ground machine is loaded from high speed to low speed. At this time, there is a metal friction sound in the transmission, and the work is weak; or the roller card beyond the clutch is dead in the wedge position; in this case, the work of I gear is powerful and the speed of the second gear is not gone.
3. Fault that can be found from the change of hydraulic oil and oil quantity.
(1) the hydraulic fluid in the transmission is increasing, and the hydraulic oil in the hydraulic box is decreasing.
This is usually caused by the damage of the oil seal of the working gear pump or steering pump, resulting in the transmission of hydraulic oil into the transmission. If there is still such a fault after replacing the oil seal, the sealing copper sleeve of the working gear pump should be checked, because the damage of the copper sleeve will cause the high pressure oil to break the framework oil seal. The clearance between the driving gear shaft and the copper sleeve of the working gear pump is controlled between 0.025 and 0.045 mm, and geometric deviation is not allowed.
(2) the amount of fluid oil in the transmission is decreasing, and the hydraulic oil content in the hydraulic box is increasing.
This situation is generally the transmission gear pump skeleton oil seal (PG45 * 62 * 12) damage, hydraulic oil is inhaled by working gear pump.
(3) the fluid oil in the transmission is decreasing and the amount of oil in the engine oil pan is increasing.
First, the sealing ring and the oil seal of the guide wheel are damaged, so that the hydraulic oil in the torque converter is leaked into the flywheel housing.
2. The O seal ring between the torque converter cover wheel and the pump wheel is damaged.
Third, torque converter hydraulic return pipe blockage, so that torque converter due to slow oil or no oil return, resulting in torque converter seal change.
4. Faults that can be found from the oil temperature gauge of the hydraulic oil and the water temperature gauge of the engine.
(1) high oil temperature and high water temperature
In this case, the troubleshooting method of water temperature should be excluded first. If the water temperature is normal, if the oil temperature is high, it can be eliminated according to the following steps.
(2) high oil temperature and normal water temperature
(1) check whether the working medium used is suitable. It is usually 30# turbine oil or 6# hydraulic oil.
(2)Check oil tank oil level. The oil level is too low or the coarse filter screen is blocked, which reduces the oil supply and causes the oil temperature too high.
(3) the blockage of the hydraulic oil radiator and too much sludge between the fins make the heat dissipation bad, resulting in the oil temperature rising.
(4)Overrunning the clutch and skidding and dying.
(5) the 312 bearings of the transmission II retaining cover are tightly assembled. The clearance between shaft and bearing should be controlled between 0.3-0.4mm.
