Here are some common problems and maintenance methods for loaders, which I hope will be helpful.
1. First and reverse gears work normally, but there is no driving force in second gear.
First, check if the gear shift lever is in the correct position. If not, readjust it. Then check if the pressure gauge drops in the second gear position. If it does, check if there is pressurized oil leaking from the outer perimeter of the figure-eight end cap of the gearbox. If there is leakage, tighten the surrounding bolts. If the above methods do not resolve the problem, the figure-eight end cap must be removed, and the O-ring and gasket replaced. If there is no pressurized oil leaking out at this point, it indicates a problem with the second gear component inside the gearbox, and the second gear component must be removed. First, check if the external oil seal of the second gear is damaged. Then disassemble the second gear component, remove the piston, and check if the piston ring, oil seal ring, and friction plate are damaged. Next, check if the guide pin inside the second gear cylinder has come loose. If the guide pin has come loose, a large amount of pressurized oil will leak from this point, causing a drop in pressure in second gear and preventing the machine from moving. Replace the seals or repair/replace the affected parts to address the cause of the pressure drop. 2. The transmission pressure, boom, bucket, and steering are all normal, but the loader still cannot move forward or backward.
First, check if the transmission is low on oil and if the oil inlet line is blocked. Then check the transmission oil pan and torque converter filter. If you find metal fragments, it's certain that parts inside the overrunning clutch in the transmission are damaged. If you find aluminum shavings in the transmission oil pan and torque converter filter, it's certain that parts inside the torque converter are damaged. In this case, the transmission and torque converter must be disassembled and inspected, and the damaged parts repaired or replaced. If the above causes are ruled out and the vehicle still cannot move, it can be determined that the bolts around the second gear component in the transmission are cut off, or the intermediate shaft output gear has come loose, preventing power output. Solution: Remove the figure-eight end cover of the transmission, take out the second gear component, and replace the cut bolt. This bolt is made of 40Cr steel and must be heat-treated; ordinary bolts must never be used as a substitute. 3. Weakness in first and reverse gears, slow driving in second gear
First, check if the pressure indicated by the transmission pressure gauge is normal. If the pressure reaches 108 kPa, increase the throttle and check if the pressure gauge needle swings. If it swings violently, it indicates that the turbine fluid in the transmission is too dirty or insufficient. Check if turbine fluid flows out of the transmission fluid level check plug. If fluid flows out, the fault is caused by dirty fluid; clean the transmission and filter, then replace the fluid. If the fluid level is normal and the transmission pressure gauge reading is normal, the fault may be a broken input secondary gear between the transmission and the torque converter, preventing power output from the secondary gear of the torque converter, allowing only the primary gear to output power. Solution: Disconnect the torque converter from the transmission and replace the damaged input secondary gear.
4. Weak drive in first gear, normal in other gears
First, check the pressure on the transmission pressure gauge to see if there is a pressure drop in first gear. If the pressure is below 98.1 kPa, first gear will definitely be weak. The causes of these phenomena are: First gear piston ring wear or excessive wear, leading to excessive pressure oil leakage and thus weak first gear drive; alternatively, damage to the O-ring seal on the first gear cylinder may cause significant pressure oil leakage. If the fault is caused by the above reasons, the transmission must be removed, disassembled, and the damaged piston rings and seals replaced. If the transmission pressure gauge does not show pressure reduction in first gear, it is likely that the transmission lever is not properly adjusted, causing weak first gear drive. The transmission lever should be readjusted to the specified position.
5. Engine runs normally, but the loader cannot move.
First, check the transmission fluid limit valve and transmission pressure gauge. If low transmission torque converter fluid is found, add new fluid. However, do not add too much, otherwise it will cause the transmission to overheat; generally, add until fluid flows out of the limit valve. Then check if the boom can be raised and lowered and if there is steering. If the boom can be raised and lowered and steering is possible, but the loader cannot move, this is due to a damaged transmission pump and insufficient fluid. If the boom cannot be raised or lowered, nor can it be steered, and the loader cannot move, this is often caused by the bolts shearing off the plate connection of the torque converter, or by a broken elastic plate. The diesel engine and transmission must be lifted out together, and then the diesel engine connection of the torque converter must be removed to locate the damaged part and replace or repair it.
6. Can only move forward, not backward
First, check if the pressure indicated by the transmission pressure gauge is normal. If the pressure drops when engaging reverse gear, it indicates excessive oil leakage in the reverse gear section. The transmission must be lifted out and completely disassembled for inspection. Remove the reverse piston, replace the piston rings, and check for damage to the friction plates. Replace severely worn friction plates and readjust the reverse gear clearance to 1.6-2.6mm. If the pressure does not drop when engaging reverse gear, it indicates that the forward gear is stuck, causing the reverse gear friction plates to slip and preventing movement in reverse. The transmission must be lifted out and disassembled to check if the isolation ring on the first gear internal gear ring is broken. Because a broken disc can jam the first gear friction plate, causing the reverse gear friction plate to slip and become ineffective, resulting in only forward movement and no backward movement. Removing and replacing the isolating ring will resolve the issue.
7. Weak drive, intermittent movement
(1) Check the oil level limit valve next to the transmission. Add new oil if it is low.
(2) If the oil level is normal, check the transmission pressure gauge. If the pressure gauge fluctuates violently, it indicates insufficient oil supply. Check the oil inlet line for blockages, the inner layer of the hoses for aging and bubbling, the torque converter filter for cleanliness, and the filter element for cleanliness. If the cause is any of the above, clean and flush the blocked pipes and filter element repeatedly with compressed air until they are clear before use. Replace any bubbly hoses.
(3) Observe the filter screen for metal blocks and aluminum shavings. If present, it indicates damaged parts in the torque converter and transmission. Disassemble and inspect the damaged parts, and replace them. 8. The transmission pressure is normal, but the vehicle cannot move in first gear or reverse; only second gear can move normally.
This fault is usually caused by shifting gears without pressing the brake pedal, which can break the first- and reverse gear connecting plate in the transmission, preventing power transmission. Second gear, however, is directly connected to the spline inside the sun gear, allowing direct power transmission, hence the ability to move in second gear.
