An electric forklift truck is a forklift that uses a battery, that is, a battery and a DC electric power source as a power source. Compared with the internal combustion forklift, the electric forklift is not only different in the power used, but also in the structure of the overall accessories. When the parts of the electric forklift are faulty, they can be eliminated one by one according to the following methods for maintenance.
1. The electrical system of the battery forklift is composed of many batteries that drive the start and stop of the oil pump motor respectively, and the main circuit that drives the start, stop, forward rotation, reverse rotation and speed regulation of the running motor. Therefore, the battery of the electric forklift is one of the most important parts of the electric forklift. When the electric forklift battery is faulty, you can refer to the following troubleshooting methods.
Fault 1: The plate is bent and cracked. The reasons for this failure are as follows:
1. The charging and discharging current is too large;
2. The temperature of the electrolyte is too high;
3. Improper installation;
4. The electrolyte contains harmful impurities such as pin acid;
5. The plate manufacturing quality is not good;
6. The forklift battery is exposed to direct sunlight.
Remedy method: Take the pole plate out of the battery tank, separate the positive and negative plates immediately after decomposition, immerse it in distilled water to wash off the acid solution, and after drying, sandwich a board of appropriate thickness between the pole plates and press it flat. Take out the electrolyte for testing, if any impurities should be replaced.
Fault 2: Plate sulfation has the following conditions
1. The surface of the plate is white crystal;
2. The battery capacity is reduced;
3. The density of the electrolyte is lower than the normal value;
4. The voltage at the beginning and end of charging is too high, reaching 2.8-3.0V;
5. Premature bubbles occur during charging;
6. The temperature rises quickly and high during charging;
7. The voltage drops quickly when discharging.
Method of exclusion:
1. When the degree of acidification of the electrode plate is slight, it can be repeatedly charged and discharged at a rate of 1/2 of the charging current value of the second stage of normal charging to make the capacity reach normal, and adjust the density of the electrolyte and the height of the liquid level.
2. When the degree of sulfation of the plates is serious, they should be treated separately after being identified. Discharge to the termination voltage at a rate of 5h, pour out the electrolyte, inject a new electrolyte with a density of 1050kg/m3, and charge with 1/2 of the charging current value in the second stage of normal charging. Rate discharge, 1/4 of the current value discharge for 1-2h, repeated several times to eliminate the sulfation of the plate.
Fault 3: The plate is short-circuited, and the fault phenomenon is as follows:
1. The open circuit voltage is low, and the voltage does not rise during charging;
2. The density of the electrolyte is low, and the density does not change during charging;
3. The temperature of the electrolyte rises rapidly during charging, and the temperature is relatively high;
4. Slow breathing when charging;
5. The battery is easy to be small. Method of exclusion:
1), clean the foreign matter in the battery tank, and update the new electrolyte;
2), flatten the plate to replace the damaged isolation plate.
Fault 4: The electrolyte is discolored, and the fault phenomenon is as follows:
1. The electrolyte is purple or light red when charging;
2. The electrolyte has brown particles during charging;
3. Serious self-discharge and rapid voltage drop.
Method of exclusion:
1. Rinse the electrode plate, the separator, the inside of the battery tank, and replace the electrolyte;
2. Reduce the charging current.
Fault 5: The plate is seriously de-powdered, and the fault phenomenon is as follows:
1. A large number of active substances fall off.
2. The battery capacity decreases.
3. When charging, there are brown fine particles in the electrolyte.
Method of exclusion:
1) At the beginning of charging, the current should not be too large. When charging to the gas, reduce the charging current in time;
2) Avoid over-discharge and over-charge;
3), remove the deposits in time to avoid short circuit of the battery;
4) Plates with severe peeling should be replaced.
Fault six: plate corrosion, fault phenomena such as:
1. The pole plate is loose and the active substance blocks protrude outward.
2. Excessive shedding of active substances.
Method of exclusion:
1. Replace the electrolyte with impurities, and thoroughly clean the plates, separators and battery tanks;
2. Avoid high temperature of electrolyte during charging;
3. Avoid overcharging;
4. Timely replacement of irreparable corroded plates.
2. Troubleshooting and troubleshooting of DC motors.
1. There should be a certain gap between the stator and the rotor, generally 0.7-5mm. If there is friction between the stator and the rotor, the troubleshooting methods are as follows:
1) The main magnetic pole fixing bolts are loose, causing friction between the stator and the rotor, which can be eliminated as long as the bolts are tightened accordingly;
2) The upper stop of the motor end cover or the stop of the frame is worn and deformed, causing the stator and the rotor to be out of axis, and even friction. The way to eliminate it is to repair the end cover.
2. The stator and rotor windings should be well insulated, and the insulation resistance should reach the standard value of the forklift manual. The working voltage of the motor is 48V and below, and its insulation resistance is measured with a 250V insulation resistance meter. If the insulation of the motor winding is damaged or the winding coil is seriously short-circuited, a new insulating material should be inserted to separate it or remove it and replace the winding directly.
3. The rotor winding should be repaired or replaced when it is open or short-circuited. 1) The open circuit of the rotor winding of the motor is mostly caused by the poor welding or de-soldering of the forklift commutator and the wire joint. The elimination method is to check out the desoldered part and re-solder it. If the winding open circuit occurs inside the individual coil, the open circuit part should be re-soldered or replaced. The short circuit of the rotor winding is often due to insulation damage. The troubleshooting method is to check the insulation damage.
4. Overhaul of the commutator. The surface of the commutator should be smooth without burn marks, the radial circular motion should be no more than 0.15mm, the rectifier should be 0.8-1.5mm higher than the mica, and it should be uniform.
1) If there is a short circuit between the commutator segments, use tools to scrape off the short-circuited metal chips, brush powder, corrosive substances and dust. Make the commutator 0.8-1.5mm higher than mica, and the chamfer width of the commutator is 0.2-0.5mm.
2) The commutator is uneven, so it should be rounded when repairing, and its surface roughness Ra is less than 1.6um.
5. Brushes. The contact area between the forklift brush and the commutator shall not be less than 80% of the total surface. There should be a clearance of 0.15mm between the brush and the brush holder.