According to the length of the loader’s operating time, the operating environment and the actual technical condition of the loader, the six-level maintenance cycle can also be appropriately adjusted.
The maintenance contents of each level are as follows:
1. Daily maintenance
It is completed by the driver himself before and after driving the car every day. The operation contents are:
1. Check the engine oil level. If it is lower than the oil dipstick mark, add oil. If it is higher than the oil dipstick mark, find out the reason for the increase in oil (dilution);
2. Check the oil level in the fuel tank;
3. Check the tightness and sealing of the engine, torque converter, hydraulic pump and steering gear, and whether there is overheating;
4. Check for oil leakage, water leakage, air leakage, liquid leakage, leakage, etc.;
5. Check whether the bolts of the drive shaft, universal joint, hinge pins, etc. are loose or lost;
6. Keep the appearance of the vehicle clean, free of oil, dirt, debris, etc.;
7. Check whether there are abnormal noises, vibrations and other abnormal phenomena in the whole machine.
2. Weekly maintenance
Professional maintenance personnel shall perform maintenance once a week. In addition to daily maintenance, they shall also complete the following:
1. Add oil according to the specified parts and the specified oil (grease) brand;
2. Clean the oil filter, fuel filter and air filter element;
3. Check and adjust the tightness of the fan and generator drive belt;
4. Check and add oil to the injection pump body;
5. Check the battery electrolyte level and density. The electrolyte level is 10 to 15 mm above the plate. If it is insufficient, add distilled water.
6. Check and adjust the free travel of each pedal;
7. Check whether the throttle, parking brake, transmission and other control levers are stuck or inflexible.
3. Monthly maintenance
Professional maintenance personnel shall perform maintenance once a month. In addition to completing daily and weekly maintenance tasks, they shall also complete the following:
1. Clean the oil filter and fuel filter element;
2. Check the tire pressure and wear. The pressure is 0.27-0.39MPa (2.8-3.0kgf/cm2). The lower limit shall be taken when working on soft ground.
3. Check whether the welds of the frame, working device and other parts with greater stress are desoldering or cracking.
Fault prevention and daily maintenance of the gearbox of wheel loader
The gearbox is one of the important transmission components of the wheel loader. It is responsible for transmitting the speed and torque from the engine to the final drive system, changing the transmission ratio between the engine and the wheels, realizing the forward and reverse gear operation of the loader, and can realize the cutting off of the power transmitted to the travel device when the engine is running, so as to meet the needs of the loader operation and driving, and facilitate the safe starting and stopping of the engine.
However, during the operation of the loader, the gearbox failure rate caused by improper use and maintenance has remained high. In particular, if the maintenance and repair procedures are not strictly followed during use, and there is a lack of timely inspection and daily maintenance, the gearbox damage and failure will be accelerated, and even the harmfulness of the consequences of the failure will be expanded.
1. The purpose of preventive maintenance
1. Through the tracking and inspection of the loader operation, planned shutdown, and good maintenance and repair arrangements for the gearbox.
2. Prevent major mechanical failures and related parts damage, and repair them before the failure occurs to save a lot of maintenance costs.
3. Make the whole machine parts have a longer service life, improve the equipment and machine efficiency, and maintain good working performance.
4. Reduce the difficulty and workload of maintenance.
2. Common failures and causes of wheel loader gearbox
1. When engaging the gear, it cannot enter the gear smoothly. The reasons are:
(1) The pressure of the pressure valve is too low;
(2) The hydraulic pump is not working properly and the seal is not good;
(3) The hydraulic pipeline is blocked;
(4) The clutch seal is damaged or leaking;
(5) The gear lever is not in place.
2. When the gearbox is shifting, the gear cannot be disengaged. The reasons are:
(1) The piston ring is swollen;
(2) The clutch friction plate is burned;
(3) The clutch return spring is invalid or damaged;
(4) The return oil pipeline is blocked.
3. The gear has been engaged, but the loader is running weakly or even unable to move. The reasons are:
(1) The friction plate is seriously worn and the gap is too large;
(2) The clutch automatic emptying valve is not sealed tightly, causing the pressure to drop;
(3) The shift control valve pipeline is blocked;
(4) The cut-off valve cannot return to its position;
(5) The shift valve positioning spring is fatigued or broken, and the steel ball jumps;
(6) The clutch piston ring and the seal ring are seriously worn, causing serious leakage.
4. The operating pressure is too low. The reasons are:
(1) The oil level in the gearbox oil pan is insufficient;
(2) The main oil channel leaks oil;
(3) The gearbox filter is blocked;
(4) The steering pump (or hydraulic pump) is damaged, causing serious internal leakage;
(5) The gearbox pressure regulating valve pressure is improperly adjusted;
(6) The gear pressure valve spring fails or breaks.
5. The gearbox automatically shifts out of gear or shifts randomly. The reasons are:
(1) The shift control valve positioning device fails. The main reason for the failure is that the positioning steel ball is severely worn or the spring fails;
(2) Due to long-term use, the position and length of the shift lever change, and the lever ratio is inaccurate, causing the operating position to deviate, thus causing misalignment.
III. How to perform preventive maintenance on the gearbox
1. According to JB/Z194-83, and combined with the actual maintenance, the following regulations should be followed:
(1) Daily maintenance: Check the oil level in the oil tank;
(2) 50 hours (or weekly): Check whether the speed control handle is flexible and effective;
(3) 250 hours (only after the first 250 hours of work): Clean the gearbox oil pan and the gearbox oil filter element;
(4) 500 hours: Clean the oil pan filter and replace the gearbox oil;
(5) 2000 hours: Disassemble the gearbox and torque converter for inspection and repair.
2. Hydraulic transmission oil is the energy carrier for the normal operation of the gearbox. In the hydraulic transmission system, the pressure, temperature and flow rate of the working fluid determine whether the transmission can work normally. Therefore, in the daily maintenance of the gearbox, special attention should be paid to the inspection and replacement of the hydraulic transmission oil.
(1) Fixed oil change interval
Changing the oil at the correct time interval is the key to ensuring the longest working life of the components in the gearbox. Only by ensuring a reasonable oil change interval can the lubricating and protective properties of the lubricating oil be brought into play. In general, the maintenance cycle recommended by the whole machine manufacturer should be used as the basis, but this can only be relative. It must be combined with the results of oil sampling and analysis to know the actual working conditions. For example, the maintenance manual requires that the oil change interval of the gearbox is 500h. According to the operation of the loader, we sample and analyze the oil every 250h or 100h to decide when to change the oil, but the lubricating oil should be replaced immediately when it is used for 1000h.
In addition to replacing new oil regularly, during routine inspections, if the oil is found to be deteriorating or mixed with impurities, it should also be cleaned and inspected, and new oil should be replaced.
(2) Use the correct method of draining and changing oil
When draining the oil, the oil temperature should reach 40-50℃, and the oil flow should be discharged under stirring. The dirty oil should be drained as thoroughly as possible; when refueling, a refueling machine with a filter device should be used to add oil.
(3) Use the correct transmission system oil. The lubricating oil used in the gearbox must meet the specifications. It should be noted that diesel engine oil cannot be added to the gearbox, because diesel engine oil will reduce the friction between moving parts such as pistons, while the transmission system oil must allow a certain friction between the friction plates when they are combined. This friction is crucial for the normal operation of the transmission system. Only by using lubricating oil correctly can the service life of the clutch friction plate be effectively extended. At the same time, correct use of oil can significantly improve the wear resistance of the gear, eliminate clutch slippage, control brake tremors and abnormal noises, increase braking force, and provide greater traction. At present, the most commonly used hydraulic transmission oils in gearboxes are 6# and 8# hydraulic transmission oils.
(4) Refer to the filter replacement cycle provided in the maintenance manual, replace the filter in time, clean the filter screen, oil drain magnet plug, and breather plug, and add lubricating oil according to the standard amount. If the gearbox oil viscosity is too high, it will cause low gearbox transmission efficiency, poor fluidity, and unfavorable heat dissipation. In addition, local dry friction may occur between parts in high-speed relative motion, which is unfavorable for lubrication; if the gearbox oil viscosity is too low, it may increase the leakage, causing the gearbox control oil pressure to be too low, resulting in failure, and the oil film strength between the transmission parts with large loads is insufficient, causing early wear of the transmission parts, which is also unfavorable for lubrication.
At the same time, a small amount of bubbles will be generated due to the stirring of the gears during normal operation. In order to prevent the accumulation of bubbles and cavitation, resulting in a decrease in the thickness of the oil film and affecting the operation of the clutch and its control valve inside the gearbox, the gearbox oil must have anti-foaming properties.
Therefore, using appropriate gearbox oil can not only protect the gearbox, extend the service life of the gearbox, and reduce the failure rate of the gearbox, but also reduce the direct cost of gearbox oil change maintenance and reduce the maintenance labor and maintenance downtime of the gearbox.
(5) All lubricants must be pure and meet the specified quality requirements after a period of sedimentation.
The refueling tools, containers and oil filling ports should be cleaned to prevent water and dirt from entering the oil.
When checking the oil level, the vehicle must be horizontal in both the longitudinal and transverse directions.
After refueling and changing the oil, be sure to check for oil leakage.
Therefore, it is very necessary to strengthen the fault prevention and daily maintenance of the gearbox during daily use. This can not only reduce the low work efficiency and delayed working hours caused by downtime and maintenance, but also prevent and avoid the occurrence of larger subsequent faults, reduce maintenance costs, and improve the safety of the machine.
