Electric reach truck troubleshooting guide: pinpoint the problem, fix it fast
Posted: Apr 7th, '25, 23:07
Electric reach forklift fault diagnosis guide: accurate positioning, fast repair
In modern logistics warehousing operations, electric reach forklifts have become the main force in cargo handling with their excellent space utilization capabilities and flexible operating performance. However, like all mechanical equipment, it is inevitable that various faults will occur after long-term high-intensity operation, affecting operating efficiency. Timely and accurate fault diagnosis is the key to ensuring that the forklift can quickly resume normal operation. Next, we will explore in depth the common faults of electric reach forklifts and their diagnosis methods.
1. Electrical system fault diagnosis
(I) Battery failure
Fault phenomenon
The forklift is difficult to start or cannot start, and the power indicator on the dashboard shows abnormality, such as the power display is too low but it is actually just fully charged, or the battery heats up severely during charging, and the charging time is too long but it is not fully charged.
During driving, the forklift power drops significantly, the speed slows down, and the cruising range is greatly shortened.
Diagnostic method
Use a professional battery tester to detect the battery voltage, capacity and internal resistance. Under normal circumstances, the voltage of a fully charged battery should reach its nominal voltage. For example, for a common 48V battery pack, the total voltage should be close to 51-52V after full charge. If the voltage is too low, it may be that the battery has a single cell lagging phenomenon. Measure the internal resistance of the battery. If the internal resistance is too large, it means that the battery is seriously aged and the capacity is attenuated.
Check the appearance of the battery to see if there is bulging or leakage. If the battery shell is found to be bulging, this is usually due to abnormal chemical reactions inside the battery, resulting in excessive gas production. At this time, the battery is basically damaged and needs to be replaced in time. For leaking batteries, not only will the electrolyte be lost and affect performance, but it may also corrode surrounding components. Stop using it immediately and repair or replace it.
Observe the charging status of the battery. If the charger displays abnormalities during charging, such as being in a fast charging state without turning the light, it may be a charger failure or a short circuit inside the battery. You can try to replace the charger for charging test. If the problem persists, it is likely that the battery is faulty.
(II) Motor failure
Failure phenomenon
When the forklift is running, the motor makes abnormal noise, such as piercing screams, buzzing or knocking sounds, accompanied by increased vibration.
The motor overheats and even smokes, the forklift power is weakened, and the goods cannot be lifted or moved normally.
The motor speed is unstable, sometimes fast and sometimes slow, affecting the smooth operation of the forklift.
Diagnostic method
First, check whether the motor wiring is loose, detached or damaged. Loose wiring will cause poor contact and cause abnormal operation of the motor, which can be solved by re-tightening the terminal. If the wiring is found to be damaged, the wires should be replaced in time to prevent short circuits from causing more serious faults.
Use a multimeter to measure the resistance value of the motor winding. Under normal circumstances, the resistance values of the three-phase windings of the motor should be basically equal and within the technical parameter range of the motor. If the resistance value of a phase winding is too large or too small, or the three-phase resistance value is unbalanced, it indicates that the motor winding has problems such as open circuit, short circuit or inter-turn short circuit. For short circuit faults, an insulation resistance tester can be used to further detect the insulation resistance between the winding and the motor housing. The normal insulation resistance should be above the megohm level. If the insulation resistance is too low, it means that the insulation performance of the motor has deteriorated and the motor needs to be repaired or replaced.
Check the carbon brushes and commutator of the motor. Severe wear of the carbon brushes will cause poor contact of the motor and affect the output power of the motor. When the carbon brushes are worn to one-third of their original length, they need to be replaced in time. If there is severe ablation, scratches or dirt on the commutator surface, it will also affect the normal operation of the motor. Sandpaper can be used to polish the commutator surface to restore it to smoothness and clean the dirt on the commutator surface.
(III) Controller failure
Failure phenomenon
Forklift operation failure, such as forward, backward, lifting, lowering and other actions cannot be performed normally, or the operation response is slow.
Fault codes appear on the dashboard. The meanings of fault codes of forklifts of different brands and models are different, but they can usually be interpreted by referring to the maintenance manual of the forklift.
The controller overheats and even produces a strange smell, which may be accompanied by smoke.
Diagnostic method
Use professional diagnostic equipment to connect to the forklift's controller interface and read the fault code. These fault codes can accurately indicate the module or circuit inside the controller that has a problem. For example, if the fault code is displayed as "current sensor failure", you can focus on checking the current sensor inside the controller and its related circuits.
Check whether the controller's cooling fan is operating normally. The controller generates a lot of heat during operation. If the cooling fan fails, it will cause the controller to overheat and cause a fault. You can judge whether the fan is normal by observing whether the fan blades are rotating or using a multimeter to measure the resistance value of the fan motor. If the fan is damaged, it should be replaced in time.
Check whether the power supply voltage of the controller is normal. Use a multimeter to measure the voltage of the power input port of the controller to ensure that it is within the rated operating voltage range of the controller. If the voltage is too low or too high, it may cause the controller to work abnormally. For abnormal voltage, check whether the power supply line has problems such as short circuit, open circuit or poor contact.
If the cause of the fault cannot be determined by the above method, try to upgrade or reset the controller software. Sometimes, controller software failure or parameter errors can also cause abnormal forklift operation. Before performing software upgrades or reset operations, be sure to back up the original parameters of the controller to prevent data loss.
2. Hydraulic system fault diagnosis
(I) Insufficient or contaminated hydraulic oil
Fault phenomenon
The forklift fork is lifted slowly or cannot be lifted, and the speed is too fast and unstable when it is lowered.
The hydraulic system makes abnormal noises when working, such as "squeaking" or "clucking".
The hydraulic cylinder crawls, that is, the fork is unstable and shakes during the lifting or lowering process.
Diagnostic method
Check the hydraulic oil level. When the forklift is in a horizontal position and the engine is turned off, observe the level gauge on the hydraulic oil tank. Under normal circumstances, the hydraulic oil level should be between the upper and lower limits of the level gauge. If the level is too low, add hydraulic oil that meets the requirements of the forklift in time. When adding hydraulic oil, pay attention to the model and quality of the oil and avoid using inferior oil.
Observe the color and texture of the hydraulic oil. Normal hydraulic oil should be clear and transparent with a slightly yellowish tint. If the hydraulic oil turns black, becomes turbid, or contains impurities or emulsification, it means that the hydraulic oil has been contaminated. Contaminated hydraulic oil will affect the normal operation of the hydraulic system and reduce the service life of hydraulic components. At this time, the hydraulic oil should be replaced in time, and the hydraulic oil tank, filter and other components should be cleaned.
Check the hydraulic oil filter. The function of the hydraulic oil filter is to filter impurities in the hydraulic oil to prevent them from entering the hydraulic system. If the filter is blocked, it will cause the hydraulic oil to flow poorly, causing the system pressure to drop, and the above-mentioned fault phenomenon will occur. You can observe the blockage indicator on the filter housing. If the indicator shows blockage, the filter element should be replaced in time.
(II) Hydraulic pump failure
Failure phenomenon
The forklift fork is unable to lift, and it is difficult to reach the normal lifting height even when it is unloaded.
The hydraulic system pressure drops significantly, and the pressure value can be visually observed through the hydraulic system pressure gauge to be lower than the rated working pressure.
The hydraulic pump makes abnormal noise when working, such as a low roar or a sharp whistle.
Diagnostic method
Use a hydraulic system pressure gauge to detect the system pressure. Connect the pressure gauge to the pressure measuring point of the hydraulic system, start the forklift, operate the fork lifting action, and observe the pressure gauge reading. If the pressure value is much lower than the rated working pressure of the forklift, it may be a hydraulic pump failure. The rated working pressure of the hydraulic system of different models of forklifts is different, generally between 12-20MPa.
Check whether the drive device of the hydraulic pump, such as the coupling between the motor or engine and the hydraulic pump, is loose, worn or damaged. If there is a problem with the coupling, the hydraulic pump will not operate normally, thus affecting the system pressure. The problem can be solved by tightening the coupling bolts and replacing the worn coupling parts.
Disassemble the hydraulic pump and check whether the internal parts are worn or damaged. Common causes of hydraulic pump failure include gear wear of gear pumps, broken or worn blades of vane pumps, and wear of plungers of plunger pumps. If internal parts are found to be damaged, the corresponding parts should be replaced according to the model and specifications of the hydraulic pump. When disassembling and installing the hydraulic pump, pay attention to cleaning to prevent impurities from entering the hydraulic system.
(III) Hydraulic cylinder failure
Failure phenomenon
When the fork is lifted or lowered, the hydraulic cylinder leaks internally or externally. Internal leakage is manifested as the fork automatically descending without operation, and external leakage can be observed as hydraulic oil leaking out of the cylinder surface.
When the hydraulic cylinder piston rod extends or retracts, it will jam or crawl, affecting the smooth operation of the fork.
The cylinder barrel is deformed, causing the piston rod to run unsmoothly, or even unable to extend or retract normally.
Diagnostic method
For internal leakage of the hydraulic cylinder, the forklift fork can be raised to the highest position, and then the engine is turned off to observe the descent of the fork over a period of time. If the fork descends too fast and exceeds the normal allowable range, it means that there is internal leakage in the cylinder. At this time, the cylinder can be disassembled to check whether the piston seal is worn, aged or damaged. If the seal is damaged, it should be replaced with a new seal in time. When installing the seal, pay attention to the installation direction and method to ensure good sealing.
For external leakage, the surface of the cylinder can be directly observed to find the leakage point. Common leakage sites include the connection between the cylinder piston rod and the cylinder barrel, the seal of the cylinder end cover, etc. If a leakage point is found, the problem can be solved by tightening the seal, replacing the damaged gasket or O-ring.
Check whether the cylinder piston rod is bent or deformed. The straightness of the piston rod can be measured using a dial indicator or other tools. If the straightness deviation exceeds the specified range, the piston rod should be straightened or replaced. At the same time, check whether the inner wall of the cylinder barrel is scratched or worn. If the inner wall of the cylinder barrel is severely damaged, it will affect the normal operation of the cylinder and the cylinder barrel needs to be repaired or replaced.
III. Mechanical system fault diagnosis
(I) Mast failure
Fault phenomenon
The mast shakes and tilts during the lifting or lowering of the fork, affecting the stability of cargo handling.
When the mast rises or falls, it makes abnormal noises, such as friction and impact.
The mast is stuck and cannot be lifted or lowered normally, or the speed is uneven during the lifting process.
Diagnostic method
Check the rollers and guide rails of the mast. Severe roller wear can cause the gantry to run unsteadily and shake. The surface wear of the roller can be observed. If there are obvious grooves or uneven wear on the roller surface, the roller should be replaced in time. At the same time, check whether the guide rail is deformed, rusted or blocked by debris. If there is a problem with the guide rail, it will affect the normal rolling of the roller and cause abnormal lifting of the gantry. The problem can be solved by cleaning the guide rail, repairing the deformed parts or replacing the guide rail.
Check the chain and sprocket of the gantry. Loose, worn or broken chains will affect the lifting speed and stability of the gantry. The chain tensioner can be adjusted to keep the chain at an appropriate tension. If the chain is severely worn or broken, the chain should be replaced in time. At the same time, check whether the tooth surface of the sprocket is worn or deformed. If there is a problem with the sprocket, it will cause poor meshing between the chain and the sprocket, causing abnormal noise and gantry lifting failure.
Check the connecting bolts and pins of the gantry. If the connecting bolts are loose or the pins are worn, the connection between the various components of the gantry will be loose, causing shaking and tilting. The connecting bolts should be checked and tightened regularly, and the worn pins should be replaced to ensure the structural integrity and stability of the mast.
(II) Tire failure
Failure phenomenon
When the forklift is driving, the vehicle deviates, that is, the vehicle deviates to one side and it is difficult to maintain a straight line.
The tire wear is uneven, and there is severe local wear or abnormal wear of the pattern.
Insufficient tire pressure causes unstable driving of the forklift and increases tire wear.
Diagnostic method
Check the tire pressure. Use a tire pressure gauge to measure the air pressure of each tire to ensure that the air pressure meets the specified value of the forklift tire. The air pressure requirements of forklift tires of different models and specifications are different, generally between 2-5MPa. If the air pressure is insufficient, it should be inflated in time; if the air pressure is too high, it should be properly deflated. Maintaining the correct tire pressure can extend the service life of the tire and improve the driving stability of the forklift.
Check the tire wear. Observe the tire tread depth and wear uniformity. Under normal circumstances, the tire tread depth should be uniform and not less than the specified wear limit. If the tire is found to be severely worn locally, it may be due to frequent sudden braking and sharp turns during driving, or inaccurate wheel alignment. For unevenly worn tires, the problem can be improved by adjusting the wheel alignment parameters and regularly rotating the tires. If the tire is severely worn and has reached the wear limit, the tire should be replaced in time.
Check the wheel alignment. Inaccurate wheel alignment can cause the forklift to deviate and the tire to wear abnormally. A professional wheel alignment instrument can be used to detect the wheel's toe, camber, caster angle and other parameters to ensure that these parameters meet the technical requirements of the forklift. If the wheel alignment parameter deviation is too large, it should be adjusted. When adjusting the wheel alignment parameters, strictly follow the forklift's maintenance manual to ensure the adjustment accuracy.
(III) Braking system failure
Fault phenomenon
The forklift brakes fail, that is, after the brake pedal is pressed, the vehicle cannot slow down or stop in time.
When braking, the vehicle deviates and drives to one side, which may be accompanied by abnormal noise.
The brake pedal travel is too long, feels soft, and has no obvious braking effect.
Diagnostic method
Check the brake fluid level and quality. When the forklift is in a horizontal position and the engine is turned off, observe the level gauge on the brake fluid reservoir. Under normal circumstances, the brake fluid level should be between the upper and lower limits of the level gauge. If the level is too low, there may be a leak in the brake system. The brake fluid should be added in time and the leak point should be found and repaired. At the same time, observe the color and texture of the brake fluid. Normal brake fluid should be clear and transparent with a slightly yellowish tint. If the brake fluid turns black, becomes turbid, or has impurities or emulsification, it means that the brake fluid has been contaminated and the brake fluid should be replaced in time.
Check the wear of the brake pads. The brake pads are key components of the brake system, and their wear directly affects the braking effect. The wear of the brake pads can be judged by observing their thickness. Generally speaking, when the thickness of the brake pads is worn to one-third of the original thickness, the brake pads need to be replaced in time. At the same time, check whether there is any foreign matter embedded between the brake pads and the brake disc. If there is any foreign matter, it should be cleaned in time to prevent affecting the braking performance.
Check the brake system pipeline. The brake system pipeline is responsible for transmitting the brake pressure. If the pipeline leaks, is blocked or ruptured, it will cause brake failure. Check the appearance of the pipeline to see if there are signs of leakage such as oil stains and bubbles. For rubber pipelines, pay attention to check whether they are aging or cracked. If problems are found in the pipeline, the corresponding pipeline components should be replaced in time. After replacing the pipeline, the brake system should be vented to ensure that there is no air in the pipeline to ensure the braking effect.
Check the master cylinder and slave cylinder of the brake system. The master cylinder and slave cylinder are the actuators of the brake system. If their internal parts are worn, damaged or poorly sealed, it will cause insufficient brake pressure or brake failure. The master cylinder and slave cylinder can be disassembled to check the wear of parts such as pistons and leather cups. If parts are found to be damaged, they should be replaced in time. When installing the master cylinder and slave cylinder, pay attention to cleaning to prevent impurities from entering the system.
By analyzing and introducing the common faults of the electrical system, hydraulic system and mechanical system of electric reach forklifts, we hope to help maintenance personnel and operators quickly and accurately locate the cause of the fault and take effective repair measures when encountering a fault.
In modern logistics warehousing operations, electric reach forklifts have become the main force in cargo handling with their excellent space utilization capabilities and flexible operating performance. However, like all mechanical equipment, it is inevitable that various faults will occur after long-term high-intensity operation, affecting operating efficiency. Timely and accurate fault diagnosis is the key to ensuring that the forklift can quickly resume normal operation. Next, we will explore in depth the common faults of electric reach forklifts and their diagnosis methods.
1. Electrical system fault diagnosis
(I) Battery failure
Fault phenomenon
The forklift is difficult to start or cannot start, and the power indicator on the dashboard shows abnormality, such as the power display is too low but it is actually just fully charged, or the battery heats up severely during charging, and the charging time is too long but it is not fully charged.
During driving, the forklift power drops significantly, the speed slows down, and the cruising range is greatly shortened.
Diagnostic method
Use a professional battery tester to detect the battery voltage, capacity and internal resistance. Under normal circumstances, the voltage of a fully charged battery should reach its nominal voltage. For example, for a common 48V battery pack, the total voltage should be close to 51-52V after full charge. If the voltage is too low, it may be that the battery has a single cell lagging phenomenon. Measure the internal resistance of the battery. If the internal resistance is too large, it means that the battery is seriously aged and the capacity is attenuated.
Check the appearance of the battery to see if there is bulging or leakage. If the battery shell is found to be bulging, this is usually due to abnormal chemical reactions inside the battery, resulting in excessive gas production. At this time, the battery is basically damaged and needs to be replaced in time. For leaking batteries, not only will the electrolyte be lost and affect performance, but it may also corrode surrounding components. Stop using it immediately and repair or replace it.
Observe the charging status of the battery. If the charger displays abnormalities during charging, such as being in a fast charging state without turning the light, it may be a charger failure or a short circuit inside the battery. You can try to replace the charger for charging test. If the problem persists, it is likely that the battery is faulty.
(II) Motor failure
Failure phenomenon
When the forklift is running, the motor makes abnormal noise, such as piercing screams, buzzing or knocking sounds, accompanied by increased vibration.
The motor overheats and even smokes, the forklift power is weakened, and the goods cannot be lifted or moved normally.
The motor speed is unstable, sometimes fast and sometimes slow, affecting the smooth operation of the forklift.
Diagnostic method
First, check whether the motor wiring is loose, detached or damaged. Loose wiring will cause poor contact and cause abnormal operation of the motor, which can be solved by re-tightening the terminal. If the wiring is found to be damaged, the wires should be replaced in time to prevent short circuits from causing more serious faults.
Use a multimeter to measure the resistance value of the motor winding. Under normal circumstances, the resistance values of the three-phase windings of the motor should be basically equal and within the technical parameter range of the motor. If the resistance value of a phase winding is too large or too small, or the three-phase resistance value is unbalanced, it indicates that the motor winding has problems such as open circuit, short circuit or inter-turn short circuit. For short circuit faults, an insulation resistance tester can be used to further detect the insulation resistance between the winding and the motor housing. The normal insulation resistance should be above the megohm level. If the insulation resistance is too low, it means that the insulation performance of the motor has deteriorated and the motor needs to be repaired or replaced.
Check the carbon brushes and commutator of the motor. Severe wear of the carbon brushes will cause poor contact of the motor and affect the output power of the motor. When the carbon brushes are worn to one-third of their original length, they need to be replaced in time. If there is severe ablation, scratches or dirt on the commutator surface, it will also affect the normal operation of the motor. Sandpaper can be used to polish the commutator surface to restore it to smoothness and clean the dirt on the commutator surface.
(III) Controller failure
Failure phenomenon
Forklift operation failure, such as forward, backward, lifting, lowering and other actions cannot be performed normally, or the operation response is slow.
Fault codes appear on the dashboard. The meanings of fault codes of forklifts of different brands and models are different, but they can usually be interpreted by referring to the maintenance manual of the forklift.
The controller overheats and even produces a strange smell, which may be accompanied by smoke.
Diagnostic method
Use professional diagnostic equipment to connect to the forklift's controller interface and read the fault code. These fault codes can accurately indicate the module or circuit inside the controller that has a problem. For example, if the fault code is displayed as "current sensor failure", you can focus on checking the current sensor inside the controller and its related circuits.
Check whether the controller's cooling fan is operating normally. The controller generates a lot of heat during operation. If the cooling fan fails, it will cause the controller to overheat and cause a fault. You can judge whether the fan is normal by observing whether the fan blades are rotating or using a multimeter to measure the resistance value of the fan motor. If the fan is damaged, it should be replaced in time.
Check whether the power supply voltage of the controller is normal. Use a multimeter to measure the voltage of the power input port of the controller to ensure that it is within the rated operating voltage range of the controller. If the voltage is too low or too high, it may cause the controller to work abnormally. For abnormal voltage, check whether the power supply line has problems such as short circuit, open circuit or poor contact.
If the cause of the fault cannot be determined by the above method, try to upgrade or reset the controller software. Sometimes, controller software failure or parameter errors can also cause abnormal forklift operation. Before performing software upgrades or reset operations, be sure to back up the original parameters of the controller to prevent data loss.
2. Hydraulic system fault diagnosis
(I) Insufficient or contaminated hydraulic oil
Fault phenomenon
The forklift fork is lifted slowly or cannot be lifted, and the speed is too fast and unstable when it is lowered.
The hydraulic system makes abnormal noises when working, such as "squeaking" or "clucking".
The hydraulic cylinder crawls, that is, the fork is unstable and shakes during the lifting or lowering process.
Diagnostic method
Check the hydraulic oil level. When the forklift is in a horizontal position and the engine is turned off, observe the level gauge on the hydraulic oil tank. Under normal circumstances, the hydraulic oil level should be between the upper and lower limits of the level gauge. If the level is too low, add hydraulic oil that meets the requirements of the forklift in time. When adding hydraulic oil, pay attention to the model and quality of the oil and avoid using inferior oil.
Observe the color and texture of the hydraulic oil. Normal hydraulic oil should be clear and transparent with a slightly yellowish tint. If the hydraulic oil turns black, becomes turbid, or contains impurities or emulsification, it means that the hydraulic oil has been contaminated. Contaminated hydraulic oil will affect the normal operation of the hydraulic system and reduce the service life of hydraulic components. At this time, the hydraulic oil should be replaced in time, and the hydraulic oil tank, filter and other components should be cleaned.
Check the hydraulic oil filter. The function of the hydraulic oil filter is to filter impurities in the hydraulic oil to prevent them from entering the hydraulic system. If the filter is blocked, it will cause the hydraulic oil to flow poorly, causing the system pressure to drop, and the above-mentioned fault phenomenon will occur. You can observe the blockage indicator on the filter housing. If the indicator shows blockage, the filter element should be replaced in time.
(II) Hydraulic pump failure
Failure phenomenon
The forklift fork is unable to lift, and it is difficult to reach the normal lifting height even when it is unloaded.
The hydraulic system pressure drops significantly, and the pressure value can be visually observed through the hydraulic system pressure gauge to be lower than the rated working pressure.
The hydraulic pump makes abnormal noise when working, such as a low roar or a sharp whistle.
Diagnostic method
Use a hydraulic system pressure gauge to detect the system pressure. Connect the pressure gauge to the pressure measuring point of the hydraulic system, start the forklift, operate the fork lifting action, and observe the pressure gauge reading. If the pressure value is much lower than the rated working pressure of the forklift, it may be a hydraulic pump failure. The rated working pressure of the hydraulic system of different models of forklifts is different, generally between 12-20MPa.
Check whether the drive device of the hydraulic pump, such as the coupling between the motor or engine and the hydraulic pump, is loose, worn or damaged. If there is a problem with the coupling, the hydraulic pump will not operate normally, thus affecting the system pressure. The problem can be solved by tightening the coupling bolts and replacing the worn coupling parts.
Disassemble the hydraulic pump and check whether the internal parts are worn or damaged. Common causes of hydraulic pump failure include gear wear of gear pumps, broken or worn blades of vane pumps, and wear of plungers of plunger pumps. If internal parts are found to be damaged, the corresponding parts should be replaced according to the model and specifications of the hydraulic pump. When disassembling and installing the hydraulic pump, pay attention to cleaning to prevent impurities from entering the hydraulic system.
(III) Hydraulic cylinder failure
Failure phenomenon
When the fork is lifted or lowered, the hydraulic cylinder leaks internally or externally. Internal leakage is manifested as the fork automatically descending without operation, and external leakage can be observed as hydraulic oil leaking out of the cylinder surface.
When the hydraulic cylinder piston rod extends or retracts, it will jam or crawl, affecting the smooth operation of the fork.
The cylinder barrel is deformed, causing the piston rod to run unsmoothly, or even unable to extend or retract normally.
Diagnostic method
For internal leakage of the hydraulic cylinder, the forklift fork can be raised to the highest position, and then the engine is turned off to observe the descent of the fork over a period of time. If the fork descends too fast and exceeds the normal allowable range, it means that there is internal leakage in the cylinder. At this time, the cylinder can be disassembled to check whether the piston seal is worn, aged or damaged. If the seal is damaged, it should be replaced with a new seal in time. When installing the seal, pay attention to the installation direction and method to ensure good sealing.
For external leakage, the surface of the cylinder can be directly observed to find the leakage point. Common leakage sites include the connection between the cylinder piston rod and the cylinder barrel, the seal of the cylinder end cover, etc. If a leakage point is found, the problem can be solved by tightening the seal, replacing the damaged gasket or O-ring.
Check whether the cylinder piston rod is bent or deformed. The straightness of the piston rod can be measured using a dial indicator or other tools. If the straightness deviation exceeds the specified range, the piston rod should be straightened or replaced. At the same time, check whether the inner wall of the cylinder barrel is scratched or worn. If the inner wall of the cylinder barrel is severely damaged, it will affect the normal operation of the cylinder and the cylinder barrel needs to be repaired or replaced.
III. Mechanical system fault diagnosis
(I) Mast failure
Fault phenomenon
The mast shakes and tilts during the lifting or lowering of the fork, affecting the stability of cargo handling.
When the mast rises or falls, it makes abnormal noises, such as friction and impact.
The mast is stuck and cannot be lifted or lowered normally, or the speed is uneven during the lifting process.
Diagnostic method
Check the rollers and guide rails of the mast. Severe roller wear can cause the gantry to run unsteadily and shake. The surface wear of the roller can be observed. If there are obvious grooves or uneven wear on the roller surface, the roller should be replaced in time. At the same time, check whether the guide rail is deformed, rusted or blocked by debris. If there is a problem with the guide rail, it will affect the normal rolling of the roller and cause abnormal lifting of the gantry. The problem can be solved by cleaning the guide rail, repairing the deformed parts or replacing the guide rail.
Check the chain and sprocket of the gantry. Loose, worn or broken chains will affect the lifting speed and stability of the gantry. The chain tensioner can be adjusted to keep the chain at an appropriate tension. If the chain is severely worn or broken, the chain should be replaced in time. At the same time, check whether the tooth surface of the sprocket is worn or deformed. If there is a problem with the sprocket, it will cause poor meshing between the chain and the sprocket, causing abnormal noise and gantry lifting failure.
Check the connecting bolts and pins of the gantry. If the connecting bolts are loose or the pins are worn, the connection between the various components of the gantry will be loose, causing shaking and tilting. The connecting bolts should be checked and tightened regularly, and the worn pins should be replaced to ensure the structural integrity and stability of the mast.
(II) Tire failure
Failure phenomenon
When the forklift is driving, the vehicle deviates, that is, the vehicle deviates to one side and it is difficult to maintain a straight line.
The tire wear is uneven, and there is severe local wear or abnormal wear of the pattern.
Insufficient tire pressure causes unstable driving of the forklift and increases tire wear.
Diagnostic method
Check the tire pressure. Use a tire pressure gauge to measure the air pressure of each tire to ensure that the air pressure meets the specified value of the forklift tire. The air pressure requirements of forklift tires of different models and specifications are different, generally between 2-5MPa. If the air pressure is insufficient, it should be inflated in time; if the air pressure is too high, it should be properly deflated. Maintaining the correct tire pressure can extend the service life of the tire and improve the driving stability of the forklift.
Check the tire wear. Observe the tire tread depth and wear uniformity. Under normal circumstances, the tire tread depth should be uniform and not less than the specified wear limit. If the tire is found to be severely worn locally, it may be due to frequent sudden braking and sharp turns during driving, or inaccurate wheel alignment. For unevenly worn tires, the problem can be improved by adjusting the wheel alignment parameters and regularly rotating the tires. If the tire is severely worn and has reached the wear limit, the tire should be replaced in time.
Check the wheel alignment. Inaccurate wheel alignment can cause the forklift to deviate and the tire to wear abnormally. A professional wheel alignment instrument can be used to detect the wheel's toe, camber, caster angle and other parameters to ensure that these parameters meet the technical requirements of the forklift. If the wheel alignment parameter deviation is too large, it should be adjusted. When adjusting the wheel alignment parameters, strictly follow the forklift's maintenance manual to ensure the adjustment accuracy.
(III) Braking system failure
Fault phenomenon
The forklift brakes fail, that is, after the brake pedal is pressed, the vehicle cannot slow down or stop in time.
When braking, the vehicle deviates and drives to one side, which may be accompanied by abnormal noise.
The brake pedal travel is too long, feels soft, and has no obvious braking effect.
Diagnostic method
Check the brake fluid level and quality. When the forklift is in a horizontal position and the engine is turned off, observe the level gauge on the brake fluid reservoir. Under normal circumstances, the brake fluid level should be between the upper and lower limits of the level gauge. If the level is too low, there may be a leak in the brake system. The brake fluid should be added in time and the leak point should be found and repaired. At the same time, observe the color and texture of the brake fluid. Normal brake fluid should be clear and transparent with a slightly yellowish tint. If the brake fluid turns black, becomes turbid, or has impurities or emulsification, it means that the brake fluid has been contaminated and the brake fluid should be replaced in time.
Check the wear of the brake pads. The brake pads are key components of the brake system, and their wear directly affects the braking effect. The wear of the brake pads can be judged by observing their thickness. Generally speaking, when the thickness of the brake pads is worn to one-third of the original thickness, the brake pads need to be replaced in time. At the same time, check whether there is any foreign matter embedded between the brake pads and the brake disc. If there is any foreign matter, it should be cleaned in time to prevent affecting the braking performance.
Check the brake system pipeline. The brake system pipeline is responsible for transmitting the brake pressure. If the pipeline leaks, is blocked or ruptured, it will cause brake failure. Check the appearance of the pipeline to see if there are signs of leakage such as oil stains and bubbles. For rubber pipelines, pay attention to check whether they are aging or cracked. If problems are found in the pipeline, the corresponding pipeline components should be replaced in time. After replacing the pipeline, the brake system should be vented to ensure that there is no air in the pipeline to ensure the braking effect.
Check the master cylinder and slave cylinder of the brake system. The master cylinder and slave cylinder are the actuators of the brake system. If their internal parts are worn, damaged or poorly sealed, it will cause insufficient brake pressure or brake failure. The master cylinder and slave cylinder can be disassembled to check the wear of parts such as pistons and leather cups. If parts are found to be damaged, they should be replaced in time. When installing the master cylinder and slave cylinder, pay attention to cleaning to prevent impurities from entering the system.
By analyzing and introducing the common faults of the electrical system, hydraulic system and mechanical system of electric reach forklifts, we hope to help maintenance personnel and operators quickly and accurately locate the cause of the fault and take effective repair measures when encountering a fault.