Common failure analysis of loaders
Common failure analysis of loaders
It is inevitable that the loader will have some failures after being used for a long time. When the loader fails, how should it be solved? Today, let’s introduce the common fault analysis and maintenance knowledge of loaders.
1. The loader is weak or does not walk at a certain speed, and the rest of the gears are normal
Judgment point:
When not walking or walking slowly, the main drive shaft rotates quickly and powerfully. When the engine speed is increased, the speed of the main drive shaft increases obviously out of proportion to the front and rear drive shafts. The transmission oil pressure is normal in neutral and other gears, and the pressure drops significantly after the gears are engaged.
Problem causes:
1) The bearing cover or nylon ring is severely worn.
2) If the bearing cover or nylon ring is good or slightly worn, then confirm that the inner seal ring and outer seal ring of the clutch are not sealed well.
Method of exclusion:
Replace the corresponding damaged parts, that is, the bearing cover or nylon ring, and inner and outer sealing rings, and readjust the gap between the shaft sleeve and the bearing cover.
Failure Analysis:
Poor walking or no walking in a certain grade can eliminate common oil circuit and component problems in various gears, such as torque converter, walking pump and pressure-reducing valve. The fault occurs only in the oil circuit between the shift control valve and the clutch piston. After the weak parts such as the bearing cover, the inner and outer sealing rings of the nylon ring are worn out, the oil supplied to the clutch piston chamber leaks a lot from the wearing parts, which causes the oil pressure to drop. In neutral or other gears, oil does not flow through consumables, so oil pressure is normal.
2. Automatically in neutral, it also drives normally when the forward gear is engaged. When the reverse gear is engaged, the machine stops running and cannot walk. The working pressure of each gear is normal
Problem causes:
Sintering and locking of the master and driven discs of the forward clutch.
The forward clutch piston stuck, seat check valve was blocked.
Method of exclusion:
Disassemble the forward clutch, clean the oil passage, replace the main friction plate and driven friction plate and related damaged parts, clean all related parts, replace the outer sealing ring, clean and dredge the one-way valve, replace the clutch friction plate, and inner and outer sealing rings.
3. When the whole machine is running normally, it suddenly does not work after the second gear is engaged. Check whether the working pressure of this gear and other gears is normal
Problem causes:
Damaged clutch shaft.
Method of exclusion:
Replace the clutch shaft and readjust the bearing clearance.
4. The whole machine will not move forward suddenly during the driving process, and the working pressure will be normal if it does not go back to change speed
Problem causes:
1). Faulty shift splitter valve or damaged accumulator (40F, 50D 50F). The pneumatic control valve stem of the shift valve is stuck or damaged.
2). Oil inlet blocked.
3). Accumulator oil passage is blocked.
4). Air Control Shutoff Valve Malfunction.
Method of exclusion:
Clean the isolation valve stem of the gearbox valve replace the air control valve to clear the related oil circuit, and repair or replace the pneumatic shut-off valve.
5. The whole machine works normally, do not turn suddenly, do not walk without lifting weights, the elastic connecting plate is damaged or the connecting wheel has teeth
Problem causes:
Remove the elastic connecting plate, the fixing bolts of the elastic coupling plate are damaged, and the gear teeth of the coupling.
Method of exclusion:
Replace the elastic coupling plate, and replace the coupling wheel.
6. The variable speed works under normal pressure, and the main drive shaft rotates quickly and powerfully when the whole machine is under heavy load. However, the whole machine cannot work normally during the shovelling process, and there is metallurgical powder in the transmission oil
Problem causes:
The high-speed and low-speed joysticks are not switched in the low-speed position, or the shift valve is not in the proper position, the 1:3 clutch is damaged, and the front clutch is damaged.
Method of exclusion:
Hook the high and low-speed levers to the low-speed position, returned Rabe.
Replace the clutch friction plate and damage-related parts.
7. Suction oil from the top of the torque converter
Problem causes:
Variable speed valve air control valve stem “?”, air leakage, hydraulic torque converter oil return filter blocked, internal oil circuit of the hydraulic torque converter or oil circuit of guide wheel seat is blocked, the oil circuit from the torque converter to transmission Oil return line is blocked.
Method of exclusion:
Replace the “?” ring of the air control valve, clean the oil return filter element or replace the filter element, clean each oil circuit or replace the guide wheel seat, and clean or replace the oil pipe.
There are many common fault analysis of loaders. This film is only the first part. Other faults and solutions will be introduced later. Please continue to pay attention to our platform.
