The structure of electric forklift is generally divided into three aspects: circuit, hydraulic and mechanical.
On the one hand, the circuit is divided into light control part and walking control part. The more important part is the power control part. The two parts are basically independent, and a few circuits are connected together. The power control part is mainly the main controller. The main control function of the electric forklift is much the same, but the structure style is different. Most of the newer parts are fully sealed, that is, all the control units are sealed in a box, and only the connectors outside are connected, Some are split type, which are generally older. The circuit board of the control card and the main transistor unit that controls the voltage and current are separated and connected with each other by wires. Because of the large number of parts, it is relatively troublesome to maintain. The peripheral auxiliary parts are various contactors and walking motors. Contactors control walking, hydraulic, power steering, and main circuit protection contactors, Then there is the accelerator that controls the speed. The LCD on the dashboard shows the working time of the vehicle. In case of a fault, it will display a fault code. In high-end vehicles, there are sensors distributed in various places on the vehicle to monitor the working condition of the vehicle. In case of an abnormal condition, an alarm will be sent to remind the driver to pay attention to safety.
The main power supply protection contactor is connected in series on the positive pole line of the main power supply, which is generally between the lower part of the main fuse and the electric control. When the vehicle breaks down or some part of the circuit is abnormal, the main control will stop supplying power to the main contactor, thus powering off the protection to avoid accidents.
The traveling contact is used to control the forward and backward movement of the vehicle. Some of them are independent and some are grouped together, but they can be controlled separately. When you step on the accelerator, the traveling contact also pulls in. The main control transistor outputs voltage to control the speed of the motor so as to control the speed of the vehicle. In this control, the traveling contactor only participates in the conduction switching of a front and rear circuit, and does not rely on the contactor to control the speed. This kind of car will hear a snap when you step on the accelerator, and also when you release the accelerator. This is an old car. Today's cars use MOS transistors to directly control the speed, eliminating the front and rear travel contactors.
The power steering contactor is used to control the power on and off of the power steering hydraulic pump. When the car is moving, it is pulled in to supply power to the steering motor. When the car stops for more than a certain time, the electronic control will automatically cut off the contactor and stop supplying power to the steering motor to save power. When the gear of some cars is moving forward or backward, the steering will always work, and it will automatically stop only when the gear is shifted to neutral, like the electronic control of GE, Some cars will automatically stop no matter where the gear is, as long as the car does not move for a certain period of time. When the accelerator is pressed again, it will automatically start to rotate. Like the electric control of Sappa and Curtis.
The function of the main hydraulic control contactor is similar to that of the power steering, that is, the opening and closing of the control circuit. When any control lever on the forklift is pressed down or pushed forward, the power supply of the contactor coil is controlled by the microswitch at the lower part of the control lever. The contactor will pull in and start to supply power to the hydraulic motor. However, most of the dual control electric forklifts do not have this contactor, Instead, an electronic control is used to control the voltage output to the hydraulic motor. (Similar to the electric control of walking control, except that there is speed regulation and there is no speed regulation. The speed regulation can control the speed of the hydraulic motor. When the forklift is unloaded, a slower speed can be used to control the operation of the fork. To save power, the governor is connected without speed regulation, and the maximum voltage is directly output.) In this way, the controlled output will not ignite due to frequent closing of the contactor. Causes aging of contacts. If there is a fault, the power is saved again.
The accelerator is commonly referred to as the accelerator, but it is not used to control the oil, but to control the voltage. By stepping on the accelerator with different forces, the electronic control circuit in the accelerator will output a different voltage to the main controller, and then the main controller will output a different voltage to the walking motor to control the speed of the forklift.
The main function of the LCD instrument panel is to display the total working time of the vehicle and the fault code of the electronic self-test when the vehicle has a fault. Finding the fault code table can provide convenience for maintenance. Some electronic controls also have a LED on the electronic control. You can also know the fault by observing the flashing times of the LED.
The traveling motor knows that the traveling motor is controlled by separate excitation and series excitation, that is, the coil connection mode is different.
The lighting circuit is not very important. Even if none of the lights on the car are on, the car can still go. However, don't neglect its importance. For your safety, please ensure that all lights can be lit. For their own convenience, but also to provide warning to others.
2、 Hydraulic part,
The hydraulic part is divided into the main working hydraulic part and the power steering hydraulic part. The main hydraulic part controls the lifting and pitching of the fork. The main hydraulic part consists of the main hydraulic motor, the hydraulic oil pump, the hydraulic reversing valve, and each hydraulic cylinder. The main hydraulic motor provides power for the oil pump. The hydraulic oil pump absorbs oil from the hydraulic oil tank, and generates great pressure for the hydraulic oil through the pressurization of the hydraulic pump. Then, the output pipeline is switched through the reversing valve to control different oil cylinders, The reversing valve is like a combined faucet. It controls different valve stems and oil flows to different places. The hydraulic oil cylinder needs to be known.
3、 For the mechanical part, I refer to everything on the car except the circuit and oil circuit as the mechanical part. It has a working mast, a differential, a transmission and a steering axle. There is a big frame
There are two common types of gantries. There are double deck gantries and triple deck gantries. The triple deck gantries are generally high, and the lifting height is higher than that of the double deck ones. They are generally three oil cylinders. There is a relatively thick free lifting oil cylinder in the middle. The advantage of this oil cylinder is that the lifting of the fork does not exceed the first section. The height of the gantry is unchanged, just like it is not raised. It is suitable for working in containers, Some double-layer gantries have only one lifting cylinder, most of them have two lifting cylinders. The disadvantage is that no matter how much the fork is raised, the height of the gantry will rise synchronously.
The differential controls the synchronization of the two wheels when driving, like the synchronization of the wheels when turning. Because the two wheels rotate at different speeds when turning and the inner half shaft rotate at different speeds, the differential must be used to adjust the speed of the gears on both sides, otherwise the gears will be damaged. The differential and transmission are connected together, and can't be seen outside. There is a semicircular part in the middle of the bridge connecting two wheels. The transmission is to slow down the speed of the motor. Since the forklift is a special vehicle that can't run like a car, speed control is very important, and the transmission also increases the torque of the motor output power when slowing down. The speed is reduced but the strength is increased.
As the name implies, the steering axle controls the vehicle's steering. The role of the steering axle is the same, but the structure is different. The current structure is a horizontal hydraulic cylinder, which is parallel to the steering axle. The two ends are connected with the wheels through arc joints. By controlling the left and right movement of the hydraulic cylinder, the deflection angle of the rear wheels of the vehicle is directly controlled to control the vehicle's driving direction. The old style has a tie rod structure, which drives the tie rod and then drives the wheel to turn. This type of steering axle is also divided into mechanical steering and hydraulic power steering. The structure of the two steering axles is basically the same, except that the former steering gear is not hydraulic, but gear driven, just like the mechanical steering on the car. The steering gear is connected to the steering axle through an iron bar or iron pipe. This kind of steering is very heavy. The workload is high. The latter is a hydraulic steering gear. The hydraulic cylinder is not installed in the car as it is now, but installed in the car vertically with the steering axle.
maintain
The maintenance of an electric forklift is much easier than that of an internal-combustion forklift. For the circuit part, check whether all the indicator lights and all the lighting and warning lights on the vehicle are normal. If not, turn on the light bulb first to see if it is good. The failure rate of the bulb is the highest. Most of the bulbs are burned out. If the lights on the vehicle are not normal, check that all the light circuits are not discolored, burnt, or broken wires, After checking and replacing the fuse, observe the place where there is no fire. If there is any fault, cut off the main power supply immediately to find out the fault point and eliminate the fault,
For the electric control circuit, always check each connector at the electric control connection. There are no ignited, loose or discolored parts. Check that there is no corrosion and oxidation at each plug. If there is any, deal with it as soon as possible. Polish and oil it with fine sandpaper to prevent corrosion. Observe the contact points of each contactor. There are no ignited, seriously worn or adhered parts. If there is any contact, replace it, After the contact is replaced, adjust the clearance between the static contact and the dynamic contact, which is generally 5 mm - 8 mm. It is easy to produce electric arc when it is too close, and it will produce spark when it is too far away and the contact force is not enough. Observe that no line contacts the contact. Prevent contacts from sparking to cause high temperature to ignite the circuit and cause accidents. Check if there is too much dust in the electric control compartment. If there is, blow it with high-pressure air. Note that high-pressure air cannot directly blow into the electric control through the gap at the plug of the electric control. Compressed air has moisture. If it is a separate electric control, check whether it is clean. In addition to the control card, blow the rest with high-pressure air. After blowing, wait a moment before driving, Remember to unplug the power plug in advance. Check that several main mega fuses are securely installed. Whether the contactor is firmly installed,
In the portal frame part, the large frame of the portal frame is not easy to be damaged, and there is no deformation, open welding, and the fork frame is not deformed, open welding, whether the fork is cracked, or seriously worn, whether the bearing of the guide rail of the portal frame can rotate flexibly, and is not damaged. It needs to be replaced in time, and the chain is not cracked, and the rust is very serious. Does the mast make noise, click and squeak when it is lifted or lowered. Timely eliminate the fault. Always oil the place where the guide rail of the mast contacts with the bearing, but not too much at one time.
If the failure rate of the differential and transmission is not man-made or due to quality problems, replace the lubricating oil in it regularly. Check frequently whether the lubricating oil is enough. You can lift the wheel on one side and let it hang in the air. Then turn on the car key, step on the accelerator and let the wheel rotate slowly. Slowly increase the speed to see if there is any noise. (Keep in mind that when the wheel is hanging in the air, you should not shift gears immediately when the wheel is accelerating. The voltage generated by the motor may burn the transistors in the electronic control device. The electronic control device is very expensive.)
The steering axle part of the steering axle part shall observe the angle of the two wheels, and frequently check the pin shaft connecting the movable joint between the wheel and the steering cylinder for oil filling, so as to prevent serious wear and inaccurate wheel steering.
The motor shall check the motor's operating condition, and there shall be no noise, whether the temperature is too high, whether the carbon brush is normal, and ensure the motor's cleanness. The carbon brush shall be checked once every six months. When the height of the carbon brush is less than 2 cm, it shall be replaced in time. The power steering motor is small, and generally there are only four carbon brushes. The walking and hydraulic brushes are all eight large carbon brushes. Check whether the pressure spring of the carbon brush holder is normal and replace it in time if it is abnormal. Check whether the motor runs smoothly and is not stuck. If so, check whether the bearing is lack of oil and replace it. Whether the wire connection is firm or not, and there is no corrosion at the wiring, if so, it should be handled in time. There is no dirt between the connector and the motor housing, so clean it in time. Check whether the commutator surface is smooth, flat and bright. If there are several groups or half a circle turns black, the coils connected to these places will have short circuit. Replace the motor or armature rotor.
The hydraulic cylinder is often observed and there is no oil leakage. The oil leakage can continue to be used, with little impact, but it is not very clean. Check whether the surface of the steel core of the hydraulic cylinder is smooth, without scars or pits. If the oil seal leaks too much, it should be replaced in time. It is best to find a professional to replace the oil seal. As long as the hydraulic cylinder is opened and drawn out, the oil seal should be replaced. If the outer dust seal is damaged, it should be replaced in time.
Whether the sound of the hydraulic pump is normal. I often drive the vehicle and get used to the sound. If the sound is not correct, it should be audible. I should check in time. I often check that the high-pressure oil pipe is free of oil leakage. If it is, replace it immediately to prevent the sudden explosion when the pressure is high. If possible, I often check whether the output pressure of the overflow valve is too high or too low.
Finally, let's talk about the battery. Ordinary electric balanced forklifts are generally 48V, but there are also special 72V and 80V forklifts. As the power source of the whole vehicle, the battery is very important. The battery is also difficult to serve. Check the voltage of each group of batteries frequently, make records, and see whether it is too high or too low. Check whether the liquid level of the battery is normal every day. The liquid level should be about 2.5 cm higher than the electrode plate, Check the specific gravity of each group of battery electrolyte every week, and adjust it in time. If the specific gravity is too low, draw out a part of the electrolyte and then inject the battery stock solution for supplement. If the specific gravity is too high, draw out a part of the electrolyte to supplement with distilled water. The specific gravity of the electrolyte is generally about 1.28, which will change slightly with the temperature change. It can be measured with a special hydrometer. Check the temperature of the battery every morning after charging, and also check the temperature of the battery before using the car, And the temperature of the battery during charging. If the temperature is too high during charging, the charging current should be reduced to lower the temperature. Otherwise, the battery will age quickly. Smell the smell of the battery during charging. Is there a smell of sulfur? If it is used for a long time under the condition of high specific gravity of the electrolyte, the battery has been vulcanized and is close to being scrapped. At this time, the daily supplement of distilled water can also be used for a period of time, but the volume is reduced. The service time is shortened. The equalizing charging is carried out once a month. The current charger is generally automatic, and there is a equalizing charging switch. Turning on this switch means equalizing charging, which is also excessive charging, so that those single low voltage batteries can replenish the power. It is good to carry out the equalizing charging once a month. Too much will damage the battery. When charging the battery forklift, it must be in a special charging room with air circulation, Hydrogen will be generated during charging, which is flammable. Excessive accumulation will cause explosion when encountering electric sparks. Smoking is not allowed nearby during charging.
