In order to understand the structure of the forklift and its working principle, the two types of forklifts with power and internal combustion are analyzed and their advantages and disadvantages are compared.
First, the overall structure of the forklift truck There are many types of forklifts, but regardless of the type of forklift, basically consists of the following four major components:
(1) Power section. Powering forklifts, generally mounted on the back of a forklift, serves as a balance weight.
(2) Chassis. The power of the power plant is accepted to move the forklift and ensure its normal walking.
(3) Work part. Used to pick and lift cargo.
(4) Electrical equipment.
Due to the differences in the structure and installation positions of the above four major components that make up the forklift truck, different types of forklifts have been formed. Counterbalanced forklifts are the most common form of forklifts. Here we use this kind of forklift as an example to introduce the composition of each part of the forklift.
1. Most of the power part of the internal combustion forklift is powered by a reciprocating piston internal combustion engine. It has a gasoline engine, a diesel engine, and a liquid petroleum gas engine; the power device of the
electric forklift is a battery and a DC series motor. In recent years, new types of forklifts have been introduced, and their power is dual fuel or dual power.
The power train is a device that receives power and transmits power to the driving train. It generally has two types, a mechanical drive train and a hydromechanical drive train. The former consists of a friction clutch, a gear transmission, a universal transmission, and a main transmission and a differential installed in the transaxle. The latter replaces the friction clutch with a hydraulic variable-speed gear, and the rest is the same as the former. In recent years, new types of forklifts have been introduced and full hydraulic transmission systems have been adopted. Reduced transmission components ensure reliability.
2. The chassis driving system is a device that ensures that the forklift rolls and supports the entire forklift. It is composed of brackets, axles, wheels, and suspension devices; the front axle of the forklift is a drive axle, which is to increase the front axle when carrying the load. The axle load is increased to improve the adhesion quality on the driving wheel, so that the ground adhesion is increased to ensure that the engine's driving force is fully utilized. The rear axle is a steering axle. The steering device is located in front of the driver, and a joystick member such as a shift lever is placed on the right side of the driver's seat.
The steering system is a system that allows the forklift to walk in the direction determined by the driver's wishes. The forklift steering system can be classified into a mechanical steering system and a power steering system based on the energy required for steering. The former uses the driver's physical energy as the steering energy, and consists of a steering gear, a steering transmission mechanism and an operating mechanism. The latter is a steering device that combines the driver's physical power and the engine power as steering energy. Under normal circumstances, the forklift turns to the required energy, and only a small part is provided by the driver, most of which is powered by the engine. Over-steering device provided. However, in the event of a failure of the steering force-applying device, it should generally be possible for the driver to independently assume the car steering task. When the forklift truck is in operation, the steering movement is variable. To reduce the burden on the driver, the internal combustion forklift uses power steering devices. The commonly used power steering devices include an integral power steering device, a semi-integrated power steering device, and a steering booster.
The brake system is a system that slows or stops the forklift. It consists of a brake and a brake transmission mechanism. The braking system can be divided into three types: human brake system, dynamic brake system, and servo brake system according to the braking energy. The former uses the driver's physical strength as the braking energy; the latter is entirely dependent on the power of the engine to convert the air or hydraulic potential energy into braking energy; the latter is a combination of the former and the former.
On the
counterbalanced forklift, counterweights are provided on the rear of the forklift to balance the weight of the goods in the forklift's front. The forklift's power unit (internal combustion engine) or batteries are generally mounted on the rear of the forklift to balance the load.
3. The working part of the working part is a direct working mechanism for forklift loading and unloading operations. It consists of the following five parts:
(1) Picking tools. It is a variety of work attachments represented by forks, used for picking, picking and scooping goods.
(2) lifting shelves. Used to install forks or Other work attachments and to pull the goods up and down together.
(3) The mast. It is the skeleton of the working device, and most of the parts of the working device are mounted on the gantry. The two-section gantry consists of an outer gantry and an inner gantry that can be raised and lowered along the outer gantry. The three-section gantry consists of three gantry frames: inner, middle, and outer.
(4) Gantry tilting mechanism. To achieve the front and rear tilt of the mast, mainly composed of tilt cylinder.
(5) Lifting mechanism. Drag the power device and traction device up and down the cargo. It is mainly composed of sprocket, chain and lifting cylinder that drives the lifting and lowering of shelves.
(6) Hydraulic control system. It is the sum of the lifting of the goods and the tilting of the gantry, as well as other actions performed by the hydraulic system to achieve a timely control device. It consists of hydraulic components, piping and control mechanisms.
4. The electrical equipment electrical equipment is mainly composed of batteries, forklift lighting, various warnings, alarm signal devices, and other electrical components and circuits. Battery forklifts have series-excited DC motors; internal-combustion engines have electric starters; in addition, gasoline forklifts have high-voltage spark ignition devices.
Second, the working principle of forklifts Forklift trucks are mostly balanced type forklifts, just like the seesaw, so we must first find out the center of gravity of the load. This center of gravity we call the load center, which is half the length of the tray. For example: The size of the tray is length (D) 1000mm x width (W) 1200mm, then the load center is 500mm. The forklift's load center is mostly based on 500mm or 600mm, so if you want to know the standard load center of the forklift, you must find out from the forklift's specification table or forklift map. The tonnage of the forklift refers to the maximum load value of loading and unloading of the forklift, and is designed based on the structural strength of the hydraulic system such as the pressure and stability of each part. The stability of a counterbalanced forklift is simply a lever principle (seesawboard). In a critical state, if there is a slight force on the cargo side, the forklift will tip over.
In vehicle design, the safety factor is generally set to ≥ 1.4 to ensure safe operation of the forklift. The load curve table shows the relationship between allowable load and load center. Operation within the range of load values can prevent accidents. 2. Comparison of internal combustion forklifts and
Electric forklifts. 1. Characteristics and working environment of internal combustion forklifts:
(1). Balanced heavy-duty diesel forklifts are large in size, but their stability is good, they are suitable for heavy-duty, there is no limit on the use time, and the use site is generally outdoors. Compared with gasoline engines, diesel engines have better dynamic performance (low speed, non-extinguishability, overload capacity, and long-term operation capability), and fuel costs are low. However, the vibration is large, the noise is large, the displacement is large, the self-weight is heavy, the price is high, and the load weight can be from 0.5 tons to 45 tons.
(2). Balanced heavy gasoline forklifts are large in size, but their stability is good, they are suitable for heavy loads, there is no limit on the use time, and the use site is generally outdoors. The gasoline engine has a small size, light weight, large output power, low noise and vibration, and low price. However, the engine's overload capacity, long-term operation ability, and fuel costs are relatively high. The weight can be from 0.5 tons to 4.5 tons.
(3). Balanced heavy-liquefied petroleum gas forklifts (LPG for short) is a balanced heavy gas forklift equipped with liquefied petroleum gas conversion device, that is to become LPG forklifts, through the transfer switch can be used to switch between gasoline and liquefied gas. The biggest advantages of LPG forklift trucks are good exhaust emissions, significantly less carbon monoxide (CO) emissions compared to gasoline engines, and lower fuel costs (15 KG of liquefied gas equals 20 liters of gasoline), which is suitable for indoor applications requiring high environmental requirements.
2. Characteristics and Working Environment of Electric Forklifts (1)
Electric Pallet Truck The main function of the
Electric Pallet truck is to realize the point-to-point movement of pallet goods on the plane. Therefore, there is no gantry lifting system, which is suitable for handling and stacking. There are three types of venues: self-propelled, standing-drive, and ride-riding. The cost varies.
(2)
Electric Pallet Stacker Forklift Electric
Pallet Stacker Forklift is a light indoor lift stacker, focusing on stacking function due to its compact body. Suitable for handling light and small materials in floor warehouses or other narrow places.
(3) The lifting mechanism of reach-on forklift
Reach Truck can move longitudinally back and forth in the forklift. When picking goods. The center of gravity of the goods falls within the four fulcrums formed by the wheels. Therefore, the reach truck has better flexibility, higher lifting safety and stability. Its load range is usually 1-2.5 tons, lifting height up to 12 meters. But because of the smaller wheels. Due to the limited nature of the property, and because of its complex structure and high cost, it is suitable for places with narrow spaces and high requirements for lifting height, and is often used in high-rise warehouses.
(4) Universal electric forklift The universal electric forklift can travel in a universal direction. In addition to the main features of the counterbalanced forklift, the three wheels can be driven in any direction at any angle. Therefore, the vehicle is steered flexibly and the goods are picked up. Afterwards, the forklift can be moved in any direction according to the site restrictions. This model solves the problem of long material in the narrow space, which greatly saves space and enables diagonal stacking and disassembly in trains and cars.
(5) Four-way electric forklift The four-way electric forklift combines the functions of a front forklift, a side fork, and a counterbalanced forklift. Structurally. It is basically the same as the reach type forklift. The gantry is located between the front and rear wheels. In the front of the vehicle, there are two legs protruding in the shape of an arm. The front of the tang is equipped with support wheels, and the goods can be with the gantry in the longitudinal direction of the forklift. Move back and forth. When the fork cargo is unloaded, the fork is extended. After the fork unloads the cargo, the fork retreats to the middle position close to the body, so the stability of the forklift is greatly improved.
Different from the reach type forklift, the two load-bearing wheels at the front end of the fork of the four-way electric forklift can be turned 90° by the steering mechanism. When the rear wheel is rotated by 90°, the entire forklift can be changed from left to right on the spot. The travel, which is equivalent to a side fork, makes it suitable for handling long materials with narrower channels. The minimum channel width can usually be within 2 meters. However, due to the complex structure, the cost is high.
(6) The main feature of the VNA narrow-channel forklift VNA narrow-channel forklift is that the gantry lifting mechanism can make three-way rotation. When stacking, the body does not need to turn, only need to turn the cargo or the gantry. Therefore, the channel width requirement is greatly reduced. At present, the minimum passage is less than 1.8 meters. But at the same time. The width of the channel also depends on the size of the tray. For example, it is still not possible to reduce the width of the passage when carrying long products. In addition, in order to ensure the stability of the lateral stacking, the weight of the whole machine is much greater than that of the three-point counterbalanced heavy-duty electric forklift, so the economical performance is slightly worse.
The following focuses on the rational selection of small tonnage counterbalanced forklifts.
Third, the two respective advantages of forklift 1, electric forklift with electric drive, compared with the internal combustion forklift, with no pollution, easy to operate, energy-efficient and so on. With the economic development and environmental protection, energy-saving requirements increase, the rapid development of electric forklifts. Market sales increase year by year. Especially in the ports, warehousing and tobacco, food, textile and other industries, electric forklifts are gradually replacing the internal combustion forklift.
2. Compared with electric forklifts, the internal-combustion forklift has good stability, is suitable for heavy load, has unlimited use time, and is generally used outdoors, such as construction sites and docks.
Fourth, summarizing the two types of forklifts have their own different characteristics and shortcomings, but also have their own living space, so there is no one which completely replaces another, and their practical significance can be summarized as follows. High production efficiency and low operating costs.
Mechanized handling is not only shorter than the traditional human-handling operations, but also reduces labor costs and costs, and improves work efficiency. In the same handling cycle, the number of movements of the forklift is significantly reduced, and the corresponding tires, transmission gears and fuel consumption of the forklift are also reduced, and the operating costs are also reduced.
2. Safe and reliable operation, reducing the accident rate.
Designed and produced by professional forklift attachment manufacturers, safety devices are designed for attachments to different industrial conditions. In abnormal situations, the clipped (or forked) goods do not slide easily, such as the pressure retaining devices of the clip attachments. The end-to-end cushioning devices, etc., reduce the accident rate.
3. The loss of goods is small.
Thanks to the unique functions of clamping, lateral movement, rotation, etc., the cargo can be transported or piled up or loaded more safely, and the degree of cargo loss can be minimized. The use of fixtures also reduces the frequency of use of pallets, and their corresponding procurement and maintenance costs are also reduced.
With the wide application of forklifts, suitable for various environments, forklifts under various conditions have been developed. Therefore, different types of forklifts can be considered for different users according to their actual needs.
