A loader is an earthwork construction machine widely used in construction projects such as roads, railways, buildings, hydropower, ports, and mines. It is mainly used to shovel soil, sand, gravel, lime, coal and other bulk materials. It can also be used for light shoveling operations on ore, hard soil, etc. By replacing different auxiliary working devices, it can also perform bulldozing, lifting and loading and unloading of other materials such as wood.
In road construction, especially in high-grade highway construction, loaders are used for filling and excavation of roadbed projects, aggregate and loading of asphalt mixtures and cement concrete yards. In addition, it can also carry out operations such as pushing soil, scraping the ground and pulling other machinery. Because the loader has the advantages of fast operating speed, high efficiency, good maneuverability, and light operation, it has become one of the main types of machines for earth and stone construction in engineering construction. Basic introduction Chinese name: Loader Foreign name: loader Date of invention: 1929 Power: Engine Scope of application: Engineering construction Main function: Loading and unloading Common name: Forklift Industry: Construction machinery development history, main components, working devices, development trends, classification , usage, selection principles, sales demand, daily maintenance, running-in period, use and maintenance, operating procedures, development history. After decades of development, Chinese loaders have made great progress. What is particularly commendable and makes the Chinese people proud is that the annual production and sales of loaders have exceeded 160,000 units. In the Chinese market where there are many international brands, domestic brand loaders still occupy the vast majority of the market. In 1978, China's annual output of loaders was only 1,315 units, and the cumulative output was only 9,454 units. In 2007, sales exceeded 160,000 units, and exports alone exceeded 10,000 units, which is more than the total historical cumulative output before reform and opening up; similarly , China's annual output of bulldozers in 1978 was only 1,909 units, and its cumulative output was 11,923 units. At that time, the import volume was relatively large. By 1980, the cumulative import volume reached 3,333 units. Especially in the late 1980s, the import volume accounted for nearly 30% of the market. In 2007, the sales volume of bulldozers exceeded 7,390 units, not only occupying most of the domestic market, but also A large number of exports, exports in 2007 alone reached 2,065 units, exceeding the total output of bulldozers in the country in 1978. Industry Development After nearly 50 years of development, especially the ultra-rapid development in the past 10 years, China's loader industry has greatly improved its product technical quality, and the gap with the world's advanced level has become smaller and smaller. In 2011, my country's loader industry sold a total of 192,100 loaders, a year-on-year increase of 14.81%. Among them, 173,271 loaders were sold in the domestic market, a year-on-year increase of 10.80; a total of 18,829 loaders were exported, a year-on-year increase of 72.25, and the export growth rate was much higher than the domestic sales growth. In the first three quarters of 2011, the demand for loaders in East China and North China was relatively large. The sales of loaders in East China accounted for 21.7% of the national sales and that in North China accounted for 19.0%. In terms of products, the market for 5T products in the first three quarters of 2011 The market share is the largest at 66.78, with a share that is 2.88 percentage points lower than in 2010, followed by 3T products, with a market share of 22.57, and a share that is 2 percentage points higher than in 2010. According to statistics, during the "Twelfth Five-Year Plan" period, my country's social fixed asset investment will still maintain a high growth rate, with a growth rate of around 20%. The country will further increase the construction of affordable housing, water conservancy projects, marine construction projects, railways, and highways. , urban public transportation and infrastructure, electric power, gas transmission projects, and transmission project construction. It is expected that by 2015, the sales volume of my country's loader industry will reach 300,000 units, of which exports will reach 40,000 units. The prospects of my country's loader industry are promising. China's modern wheel loaders originated from the Z435 model in the mid-1960s. This machine has an integral frame and rear axle steering. After several years of hard work, on the basis of absorbing the world's most advanced wheel loader technology at the time, a shovel-type wheel loader with a power of 162KW was successfully developed, which was designated as the Z450 (later ZL50), and in 1971 It officially passed the expert appraisal on December 18, 2018.
In this way, China's first articulated wheel loader was born, thus creating the history of the formation and development of China's loader industry. The Z450 loader has the basic structure of modern wheel loaders such as hydromechanical transmission, power shift, dual-axle drive, hydraulic control, articulated power steering, and pneumatic afterburning, which was the world's advanced level at that time. It also basically represents the basic structure of China's first generation of wheeled loading. In terms of overall performance, the machine has good power, and the insertion force has a series of advantages such as large breakout force, flexible maneuverability, light operation, and high operating efficiency. In 1978, according to the requirements of the Ministry of Machinery, Tiangong Institute formulated the Chinese wheel loader series standards based on Liugong Z450. When formulating the standard, Z was retained to represent loader, L was used to replace "4" to represent wheel, and Z450 was changed to ZL50. In this way, the Chinese ZL wheel loader series standard based on Liugong ZL50 model was formulated. This is A major turning point in the history of China's loader development. After the standard was formulated, according to the industry division at that time, Liugong and Xiamen Gong manufactured large and medium-sized wheel loaders above ZL40, Chenggong and Yigong manufactured small and medium-sized wheel loaders below ZL30, and gradually formed Liugong, Xiamen Gong. At that time, there were four backbone loader enterprises including Chenggong, Chenggong and Yigong. By the late 1970s and 1980s, China's loader manufacturing companies had increased to more than 20, and the Chinese loader industry had initially formed. Chinese wheel loaders have developed into the third generation, but the most basic structure is still evolved from the Z450 (ZL50). The second generation did not change much, and the third generation changed slightly. In 2001, the total sales volume of China's loader industry exceeded 30,000 units, ranking at the forefront of the world's loader market. Therefore, China has become the world's largest loader production and sales country. In 2006, the total sales volume of China's loader industry was 129,793 units, an increase of 15.3% from 112,527 units in 2005, a net increase of 17,266 units. Its net increase exceeded the "Eighth Five-Year Plan" of China's loader industry. Based on the total sales volume of any previous year, it can be said that 2006 was another prosperous harvest year for China's loader industry. From January to November 2007, the cumulative sales of 26 major loader companies were 143,794 units, an increase of 34,397 units year-on-year (109,397 units), an increase of 31.4%; the cumulative exports were 8,606 units, accounting for 6.0% of the cumulative sales, an increase year-on-year (3,234 units) 5372 units, an increase of 166.1. In 2008, the growth rate of China's loader industry continued unabated. From January to July, the cumulative sales of loaders nationwide were 120,449 units, a year-on-year increase of 30.5%. While China's loader industry is developing, some problems are increasingly emerging. In particular, the industry has extremely low entry barriers. Vicious price competition has led to low corporate profitability, lack of marketing concepts, difficulty in market expansion, poor product quality and reliability. In addition, aging products and organizational structures and difficulty in digesting the increased costs of service upgrades are serious factors. Restricting the further development of the industry and the improvement of quality. Therefore, Chinese loader companies must seize the new development situation, embody differentiation strategies and cost leadership strategies in product research and development, and continue to strengthen the construction of the industry's scientific research and development system with the company's national technology centers and universities and scientific research institutes as the main body. Create value chain marketing, strengthen brand building, and enhance brand value. Only in this way can we remain invincible in the new situation.
The main components include engine, torque converter, gearbox, front and rear drive axles, referred to as the four major parts 1. Engine 2. There are three pumps on the torque converter, the working pump (supplies lifting and tipping pressure oil) and the steering pump (supplies Steering pressure oil) The variable speed pump is also called a traveling pump (supplies torque converter and gearbox pressure oil). Some models of steering pumps are also equipped with a pilot pump (supplies control valve pilot pressure oil). 3. Working hydraulic oil circuit, hydraulic Fuel tank, working pump, multi-way valve, lift cylinder and dump cylinder 4. Travel oil circuit: transmission sump oil, travel pump, one way into the torque converter, one way into the gear valve, transmission clutch 5. Drive: Transmission Shaft, main differential, wheel reducer 6. Steering oil circuit: oil tank, steering pump, steady flow valve (or priority valve) steering gear, steering cylinder 7. The gearbox has integrated (planetary type) and split ( The shoveling and material loading and unloading operations of the loader with two types of working devices (fixed-axis type) are realized through the movement of its working devices. The working device of the loader consists of bucket 1, boom 2, connecting rod 3, rocker arm 4, bucket cylinder 5, boom cylinder 6, etc. The entire working device is hinged on the frame 7. The bucket is articulated with the bucket cylinder through a connecting rod and rocker arm to load and unload materials. The boom is articulated with the frame and boom cylinder to lift and lower the bucket. The flipping of the bucket and the lifting and lowering of the boom are hydraulically controlled. When the loader is operating, the working device should be able to ensure that: when the bucket cylinder is locked and the boom cylinder is raised or lowered, the linkage mechanism causes the bucket to move up and down or close to it to prevent the bucket from tilting and spilling materials; When the arm is in any position and the bucket rotates around the hinge point of the boom for unloading, the tilt angle of the bucket is not less than 45°. After unloading, the bucket can be automatically leveled when the boom is lowered. Based on the structural types of loader working devices at home and abroad, there are seven main types, namely, according to the number of components of the linkage mechanism, they are divided into three-rod type, four-rod type, five-rod type, six-rod type and eight-rod type, etc.; According to whether the input and output rods have the same steering direction, they are divided into forward and reverse linkage mechanisms, etc. The bucket structure of a loader for earthmoving engineering is usually made of welded low-carbon, wear-resistant, high-strength steel plates. The cutting edge is made of wear-resistant medium manganese alloy steel. The side cutting edges and reinforced corner plates are made of high-strength and resistant steel plates. Made of ground steel material. Bucket cutter shapes are divided into four types. The selection of tooth shape should consider factors such as insertion resistance, wear resistance and ease of replacement. The tooth shape is divided into sharp teeth and blunt teeth. Tire loaders mostly use sharp teeth, while crawler loaders mostly use blunt teeth. The number of bucket teeth depends on the bucket width, and the bucket tooth spacing is generally 150-300mm. The bucket tooth structure is divided into two types: integral type and split type. Small and medium-sized loaders mostly use the integral type, while large loaders often use the split type due to poor operating conditions and serious bucket tooth wear. The split bucket tooth is divided into two parts: basic tooth 2 and tooth tip 1. After wear, only the tooth tip needs to be replaced. Development Trend Domestic wheel loaders are transitioning from low-level, low-quality, low-price, and functional models to high-level, high-quality, mid-price, economical and practical models. In the transition from imitation to independent development, major manufacturers continue to invest in technology, adopt different technical routes, and innovate in key components and systems to get rid of the status quo of similar product designs without their own characteristics and advantages. From low-level disorder Stand out from the vicious circle of competition and become the leader in the loader industry. (1) Large and small wheel loaders are limited by objective conditions and total market demand during the development process. The most competitive medium-sized loaders will be updated faster and faster. (2) Based on the actual conditions of each manufacturer, redesign the overall design, optimize various performance indicators, strengthen the strength and stiffness of structural parts, and greatly improve the reliability of the entire machine. (3) Refine the system structure. Such as vibration reduction of the power system, structural optimization of the heat dissipation system, optimization of the performance indicators of the working device, dust protection of each hinge point, industrial shape design, etc. (4) Use electronic technology and load sensing technology to realize the automatic shifting of the gearbox and the application of the hydraulic variable system to improve efficiency, save energy, and reduce loader operating costs. (5) Improve safety and comfort. The cab will gradually be equipped with FOPS and ROPS functions. The environment in the cab will be closer to the direction of the car. The steering wheel, seats, and each control handle can be adjusted to allow the operator to work in the right position. (6) Reduce noise and emissions and strengthen environmental protection indicators.
As people's awareness of environmental protection increases, it is urgent to reduce the noise and emissions of loaders. Many large cities have formulated noise and emission standards for motor vehicles. If engineering construction machinery does not meet the emission standards, it will be restricted in the area. Sale. (7) Make extensive use of new materials, new processes, and new technologies, especially mechanical, electrical, and hydraulic integration technologies, to improve product life and reliability. (8) Simplify maintenance to the greatest extent, reduce maintenance frequency and repair time as much as possible, increase maintenance space, widely use electronic monitoring and surveillance technology, further improve fault diagnosis systems, and provide drivers with methods to troubleshoot problems. Classification Commonly used single bucket loaders are classified according to engine power, transmission form, traveling system structure, and loading method. 1. Engine power: ① Small loaders with power less than 74kw. ② Medium-sized loaders with power between 74 and 147kw ③ Large loaders with power between 147 and 515kw ④ Extra-large loaders with power greater than 515kw 2. Transmission form: ① Hydraulic-mechanical transmission, small impact and vibration, long service life of transmission parts. Easy to operate, automatic adjustment between vehicle speed and external load, generally used on medium and large loaders; ② Hydraulic transmission: stepless speed adjustment, easy to operate, but poor start-up, generally only used on small loaders; ③ Electric transmission: stepless speed regulation, reliable operation, simple maintenance, and high cost. It is generally used on large loaders. 3. Walking structure: ① Tire type: light weight, fast speed, flexible, high efficiency, not easy to damage the road surface, large ground specific pressure, poor passability, but widely used; ② Crawler type: small ground specific pressure, good passability , low center of gravity, good stability, strong adhesion, large traction, large specific cutting force, low speed, relatively poor flexibility, high cost, and easy to damage the road surface when walking. 4. Loading and unloading methods: ① Front unloading type: simple structure, reliable work, good vision, suitable for various working sites, wide application; ② Rotary type: The working device is installed on a turntable that can rotate 360°, and side unloading is not required U-turn, high operating efficiency, but complex structure, large mass, high cost and poor side stability, so it is suitable for smaller sites. ③Rear unloading type: front-end loading, rear-end unloading, high operating efficiency, but poor operating safety. Purpose: The loader is mainly used for shoveling, loading, unloading, and transporting bulk materials such as earth and stone. It can also perform light shoveling operations on rocks and hard soil. If different working devices are replaced, it can also complete the work of bulldozing, lifting, loading and unloading other materials. In highway construction, it is mainly used for filling and excavation of roadbed projects, aggregate and loading operations in asphalt and cement concrete yards. Because of its advantages such as fast operating speed, good maneuverability and light operation, it has developed rapidly and has become the main machine in earth and stone construction. Selection Principles 1. Selection of machine model: The selection and determination are mainly based on the working situation and purpose. Generally, for operations in quarries and soft bases, tire loaders equipped with anti-skid chains are often used; 2. Power selection: Diesel engines for engineering machinery are generally used. When operating in special areas, such as places with an altitude higher than 3000m, a diesel engine should be used. Special plateau diesel engine; 3. Selection of transmission type: Hydraulic-mechanical transmission is generally used. A key component is the choice of torque converter form. Loaders produced in China mostly use twin-turbines and single-stage two-phase torque converters. 4. When selecting a loader, full consideration should be given to the loader's braking performance, including multiple in-line braking, parking braking and emergency braking. There are three types of brakes: shoe type, caliper disc type and wet multi-disc type. The driving mechanism of the brake generally uses an afterburner device, and its power sources include compressed air, air cap oil and hydraulic type. The most commonly used is the air cap oil braking system, which generally adopts a dual-circuit braking system to improve driving safety. Sales demand The loader market was relatively sluggish in 2013, with production and sales declining to varying degrees year-on-year. Data showed that the total sales of loaders in the first quarter was 41,486 units, a year-on-year decrease of 19.0%. Among them, sales in February were low, not only down 54.1% year-on-year, but also down 6.1% month-on-month. In March, sales rebounded significantly, falling 6.6% year-on-year and increasing 201.2% month-on-month. It can be seen that the future of the loader market will also have expectations.
By April, loaders also achieved positive year-on-year growth. In May, loader sales reached 19,045 units, a year-on-year increase of 14, higher than the 4 in April. Of the domestic market demand for loaders, 32% comes from the mining industry, 33% from infrastructure construction, 14% from water conservancy construction, and 8% from the real estate industry. The development of these industries largely depends on the level of domestic fixed asset investment. In the first half of 2013, my country's fixed asset investment (excluding rural households) was 18,131.8 billion yuan, and the cumulative growth rate of fixed asset investment was 20.1, continuing the steady growth trend. In the second half of the year, there will be no major changes in the internal and external factors that determine investment trends. Therefore, the central government will continue to strengthen the regulation of investment. While maintaining an investment growth rate of around 20%, the investment structure will be further optimized. We predict that infrastructure investment will proceed smoothly in the second half of 2013, and the mining industry will emerge from the downturn under the control of governments and enterprises. During the "Twelfth Five-Year Plan" period, the country will invest 1.8 trillion yuan in water conservancy. , the real estate industry will also gradually get out of the current chaotic situation with the joint coordination of governments and real estate developers. Therefore, under the combined effect of many factors, the loader industry will also gradually pick up the construction machinery industry under the appropriate control of the enterprises themselves. Routine maintenance After a loader leaves the factory, there is generally a running-in period of about 60 hours (some are called a run-in period), which is based on the technical characteristics of the loader at the initial stage of use. The running-in period is an important step to ensure the normal operation of the loader, reduce the failure rate, and extend its service life. Some users ignore the special technical requirements of the new machine's running-in period due to a lack of common sense in using loaders, tight construction schedules, or wanting to obtain benefits as soon as possible. Some users even believe that the manufacturer has a warranty period anyway, and the manufacturer is responsible for repairing the machine if it breaks down. Therefore, the machine is overloaded for a long time during the running-in period, resulting in frequent early failures of the machine. This not only affects the normal use of the machine, but also affects the normal use of the machine. The service life of the machine is shortened, and the project progress is also affected due to machine damage. Therefore, full attention should be paid to the application and maintenance of the loader during the running-in period. During the running-in period, the wear rate is fast. Due to the influence of factors such as processing, assembly and adjustment of new machine parts, its friction surface is rough, the contact area of ??the mating surface is small, and the pressure-bearing condition of the surface is uneven. During the operation of the machine, the concave and convex parts on the surface of the parts engage and rub against each other, and the metal chips that fall off continue to participate in the friction as abrasives, which accelerates the wear of the mating surfaces of the parts. Therefore, parts (especially the mating surfaces) are easily worn during the running-in period, and the wear rate is high. At this time, if the work is overloaded, it may cause damage to the parts and cause early failure. Poor lubrication: Because the fitting clearance of newly assembled parts is small, and due to assembly and other reasons, it is difficult to ensure the uniformity of the fitting clearance. The lubricating oil (grease) is not easy to form a uniform oil film on the friction surface to prevent wear. This reduces the lubrication efficiency and causes early abnormal wear of the machine parts. In severe cases, the friction surface of the precision fit will be scratched or bitten, leading to failure. Loose newly processed and assembled parts have deviations in geometric shapes and fitting dimensions. In the early stages of use, they are easily affected by alternating loads such as shock and vibration, as well as by factors such as heat and deformation, as well as excessive wear and tear. Loose the parts that were originally fastened. Leakage occurs due to the looseness and vibration of machine parts and the influence of heat on the machine. Leakage will occur on the sealing surface of the machine and the pipe joints. Some casting, processing and other defects are difficult to find during assembly and debugging, but due to the Due to vibration and impact, this defect is exposed and manifests as oil (water) leakage (leakage). Therefore, leakage is prone to occur during the running-in period. Operational errors are often caused by insufficient understanding of the structure and performance of the machine (especially by new operators), which can easily cause malfunctions or even mechanical accidents due to operating errors. Use and Maintenance Since construction machinery is a special vehicle, operators should receive training and guidance from the manufacturer, have a full understanding of the structure and performance of the machine, and obtain certain operating and maintenance experience before operating the machine.
The "Product Instructions for Use and Maintenance" provided by the manufacturer is essential information for operators to operate the equipment. Before operating the machine, be sure to read the "Instructions for Use and Maintenance" and perform operation and maintenance as required. Pay attention to the workload during the running-in period. Half of the workload during the running-in period should not exceed 60% of the rated workload, and a suitable workload must be arranged to prevent the occurrence of overheating caused by long-term continuous operation of the machine. Pay attention to frequently observing the indications of each instrument. If any abnormality occurs, the machine should be stopped in time to eliminate it. The operation should be stopped before the cause is found and the fault is not eliminated. Pay attention to frequently checking the level and quality of lubricating oil, hydraulic oil, coolant, brake fluid and fuel oil (water), and pay attention to checking the sealing of the whole machine. During the inspection, it is found that there is too much oil and water, and the cause should be analyzed. At the same time, the lubrication of each lubrication point should be strengthened. It is recommended that the lubrication points should be filled with grease every shift during the running-in period (except for special requirements). Keep the machine clean, adjust and tighten loose parts in time to prevent loose parts from aggravating wear and tear or causing parts to be lost. After the running-in period is over, the machine should be subject to mandatory maintenance, inspection and adjustment, and attention should be paid to oil replacement. In short, the requirements for loader use and maintenance during the running-in period can be summarized as: strengthening training, reducing load, paying attention to inspections, and strengthening lubrication. As long as you pay attention to and perform maintenance on the loader during the running-in period as required, the occurrence of early failures will be reduced, the service life will be extended, the operating efficiency will be improved, and the new machine will bring you more benefits. Operating procedures 1) Before driving and operating, operators should be familiar with the loader's various performance, structure, technical maintenance, and operating methods, and operate according to regulations. 2) Except for the cab, passengers are strictly prohibited elsewhere on the aircraft. 3) When unloading materials into the car, the bucket must be raised to a height that does not touch the car fender. Strictly prevent the bucket from touching the car box. It is strictly prohibited to pass the bucket over the top of the car cab. 4) Use automatic deceleration when going downhill, and do not step on the clutch pedal to prevent the power from being cut off and causing a rolling accident. 5) The loader should be stopped immediately after wading in water for inspection. If it is found that the brake fails due to water immersion, continuous braking should be performed and heat should be used to remove moisture from the brake pads so that the brakes can return to normal as soon as possible. 6) When the loader is working, no one is allowed to stand directly in front of it, and no one is allowed to be in the bucket during driving. 7) When working, it is strictly forbidden for people to stand under the shovel arm, and unrelated personnel and other machinery are prohibited from working and passing here. 8) It is strictly prohibited to use high-speed operation. 9) When the operator leaves the driving position, the bucket must be dropped to the ground, the engine must be turned off, and the power supply must be cut off.