The loader is a widely used in highway, railway, construction, electricity, ports, mines and other construction projects of earth and stone construction machinery, which is mainly used for loading soil, gravel, lime, coal and other bulk materials, is also available on the rock, hard soil for mild digging operation. Dress up different auxiliary assembly can also be bulldozing, lifting and other materials such as timber loading and unloading operations. On the road, especially in high grade highway construction, the loader for subgrade engineering excavation, asphalt mixture and cement concrete material field of aggregate and loading operations. In addition can also be pushed and transported soil, scrape the ground and traction machinery and other operations. Because the loader is operating speed, high efficiency, good mobility, convenient operation and other advantages, so it becomes the construction of earth and stone construction of one of the main machine.
China loader industry development
Chinese modern wheel loader began in the nineteen sixties middle typeZ435.
The machine as a whole frame, rear axle steering. After several years of efforts, in the absorption of the world 's most advanced technology on the basis of wheeled
loader, the successful development of the power of 162KW shovel type wheel loader, stereotyped as Z450(later ZL50), and in December 18, 1971 officially identified by experts. So the birth of China's first articulated wheel loader, thus inaugurating China loader industry formation and development. Z450 type loading machine with hydraulic mechanical transmission, power shift, double drive, hydraulic control, articulated steering, braking and other modern afterburner gas pushes the wheel loader 's basic structure, then the world's advanced level. Also basically represents the first generation of Chinese basic structure for wheel loader. The machine is in overall performance has good dynamic performance, insertion force a large breakout force, flexible, convenient operation, high operation efficiency and a series of advantages. 1978, day according to the machinery of the request, to formulate a willow labour Z450as a basic type of wheel loader series of standard chinese. When formulate standard, the Z represents loader, replace L with"4" represents the wheel, Z450for ZL50, then worked out in Liu of type ZL50as a basic type of Chinese ZL wheel loader series standard, this is the Chinese loader history significant turning point. The standard developed by the industry division of labor, industrial engineering, Liu manufacturing ZL40above is large and medium-sized wheeled loaders, as workers, appropriate industry manufacturing ZL30below the small wheel loader, and gradually formed a willow industry, building, as workers and to workers at the time of the loader four backbone enterprises. To 70 time end, at the beginning of 80 time China loader manufacturing enterprises has increased to more than 20, preliminary formed China loader industry. So far, China wheeled loader has been developed to the third generation, but the basic structure remains by Z450( ZL50) evolved. The second generation is not varied greatly, the third generation changes slightly larger number. In 2001 China loader industry total sales have exceeded30000, house world the loader to the forefront of the market. Therefore, at present, China has become the world's loader power production. In 2006China loader industry entire industry total sales of 129793units, more than112527 units in 2005, up 15.3%, a net increase of17266, net increment over China loader industry" eight five" any previous year total sales, it can be said that in 2006China loader industry is also a prosperous year. 2007 1-11 month, loader26 major enterprises sold a total of 143794, an increase of 34397(109397), an increase of 31.4%; total exports for8606, accounting for total sales volume 6%, (3234) increase compared to the same period5372, amplitude is amounted to 166.1%. In 2008, China loader industry growth rate reduction,1-7month, accumulative total of countrywide fork-lift truck sales volume is 120449, an increase of 30.5%. China loader industry in development at the same time, some problems also are shown increasingly come out. Especially the industry enters a doorsill low, vicious price competition leads to lower profitability of the business, the marketing idea is missing, the market is expanding, product quality and reliability, moreover, the product structure and the aging and upgrading of services increased cost is difficult to digest and other factors severely restrict the further development of industry and the improvement of quality. Therefore, Chinese loader enterprises must seize new development situation, in the product R & D reflect the differential strategy and cost leading strategy, continue to
strengthen the industry to the enterprise center of national level technology and institutions of higher learning and scientific research institutes as the main research and development system construction, build the value chain marketing, strengthen brand construction, enhance brand value, only in this way to remain invincible in the new situation. China's largest wheel loader is Xugong LW1200K.
In November 23, 2010, baumachina2010 exhibition held a grand occasion, the Xu labor science and technology shock launched the largest tonnage Loaders -- LW1200K, and spot sales, in twenty-first Century second ten years come, leading the Chinese loader product technology development in the new era. The appearance of LW1200K, make the Xugong and Europe, beauty enterprises juxtaposed, to become the world's ability to develop the level of products, one of the four giants. LW1200K loader is Xugong based on market demand, targeting the international high-end technology mainstream, independent research and development of new products, is currently China's largest tonnage wheeled loader, with international advanced technology, equipment, international first-class parts, reflects the quality, safety and environmental values. And successfully passed by the Jilin University, Beijing Institute of Technology, Southeast University, China University of Mining and Technology and a number of industry experts identification. Identification of the committee gave a high evaluation, and agreed that" is China loader industry a major technological upgrade and breakthrough, to break foreign large loaders absolute monopoly, promote China loader industry technical progress, leading the loader industry toward high reliability, high technology content, high performance, large tonnage the direction of development of epoch-making significance". Use
The loading machine is mainly used for loading, unloading, shovel, earth and stone type bulk material, also on rock, hard soil for mild digging. If a different work device, can also complete the bulldozing, lifting, loading and unloading materials work. In the highway construction is mainly used for subgrade engineering excavation, asphalt and cement concrete material field of aggregate, charging and other operations. Due to its high operating speed, good maneuverability, convenient operation and other advantages, and is developing very quickly, become the main machinery construction of earth and stone.
The commonly used single bucket loading machine, according to the power of the engine, transmission, walking system structure, loading way classification. In 1, the engine power : the power is less than 74kw for small loader. The power in the 74 ~147kw for medium-sized loaders and power in the 147 ~515kw for large loader; the power is more than 515kw for oversize loading machine. In 2, transmission forms: of hydraulic mechanical transmission, small impact vibration, transmission and long service life, convenient operation, speed and load can be adjusted automatically,
generally in large loader uses; the hydraulic transmission: stepless speed regulation, between the operation is started, but poor, generally only in small loader on the use of; the power transmission: stepless speed regulation, reliable work, simple repair, high cost, generally in large loaders used. 3, walking structure : 1tire type: light quality, speed, flexibility, high efficiency, not easily damaged pavement, ground pressure, poor through, but are widely used; the crawler: grounding than the small, through the good, low center of gravity, good stability, strong adhesion, large traction force, cutting force, ratio of low speed, flexibility, high cost, relative difference when walking easily damaged pavement. 4, loading and unloading method : 1before unloading type: has the advantages of simple structure, reliable work, good vision, suitable for a variety of operating field, wide application; the rotary: working device is installed on the rotary360O table, lateral unloading without turning, high work efficiency, but the complex structure, quality, high cost, side stability is poor, is applicable to small venues. The unloading type: front-end loaded, unloaded, the operation efficiency is high, the rear safety good.
Type selection of main basis: operation and use to select and determine the. Generally in the quarry and soft base operations, using a crawler loader;2, power selection: the general use of engineering mechanical diesel engine, the special regional operations, such as elevation higher than that of 3000m place, should use the special high prototype diesel engine;3, transmission type selection: selection of hydraulic - General Mechanical transmission. The key components are converter selection form. China now produces loader selects the double single stage, two phase fluid power converter. 4, in the selection of the loader, and fully consider the loader braking performance, including a plurality of the brake, parking brake and emergency brake three. Brake shoe type, a caliper disc and wet type three. Brake drive mechanism generally use the afterburner device, its power source with compressed air, gas cap oil and the hydraulic pressure type three kinds. Currently used is the gas cap oil brake system, generally using a dual circuit brake system, to improve the running safety.
Includes engine, torque converter, transmission, front, rear drive axle, referred to as the big four. The 1 engine. The 2torque converter with three pumps, pump (the supply of lifting, tipping bucket oil pressure ) steering pump ( power steering oil pressure ) variable speed pump running pump ( also called for strain torque converter, transmission pressure oil ), some models of steering pump is also provided with a pilot pump ( supply control valve pilot pressure oil ). 3. Work hydraulic oil, hydraulic oil tank, pump, valve, a lifting oil cylinder and a bucket oil cylinder. 4 walking path: gearbox sump pump, walk, walk into the converter a road into the shift valve, gearbox clutch. The 5 drive: drive shaft, a main gear,
a wheel side speed reducer. 6: steering oil tank, power steering pump, steady flow valve ( or the priority valve ) steering gear, steering cylinder. 7gearbox is one of the ( planetary ) and body ( fixed shaft type ) two.
Loader shovel and material handling work through its working device movement to achieve. Working device of loader bucket, boom by12,34connecting rod, rocker arm and bucket cylinder5, the arm cylinder6. The working device is hinged on the frame 7. Bucket through the connecting rod and the rocker arm and bucket rotating oil cylinder is hinged, is used for loading and unloading materials. Boom, boom cylinder is hinged with the frame, for lifting bucket. The flip bucket and boom lifting hydraulic control. Loader working device can ensure the operation should be: when the bucket cylinder latch, a boom cylinder lifting or lowering, a linkage that bucket on translational or close to the translation, in order to avoid falling material bucket tilt; when the movable arm is in any position, bucket orbiting arm joint rotation when discharging, bucket tilting angle less than 45 degrees, after unloading boom decline and can make automatic bucket leveling. At home and abroad the loader working device structure, there are seven main types, namely according to connecting rod mechanism component of different number, divided into three bar, four bar, five bar, six bar and eight pole type; according to the input and output rod steering whether the same is divided into positive transfer and inversion of connecting rod mechanism. Earthwork engineering loader bucket bucket body structure, the common low carbon, wear-resistant, high strength steel welded, cutting edge adopts wear-resistant manganese alloy steel material, the side cutting edges and reinforcing corner plate with high strength abrasion resistant steel material. Bucket cutting knife shape divided into four. Tooth shape selection should consider inserting resistance, wear resistance and easy to change and other factors. Tooth profile is divided into a sharp and blunt teeth, wheel loader with pointed teeth, and the crawler device boot with blunt teeth. Bucket tooth number as the bucket and bucket tooth width, apart from the general150-300mm. Bucket tooth structure integral and split in two, small loaders with integral type, while large loader due to poor operation condition, bucket teeth wear serious, often using split. Split bucket tooth is divided into the basic gear2 and a tooth tip1two parts, wear only need to replace the tooth tip.
Loader technology acceptance
1 loader driving operation certificate from around the Bureau of work safety certification. 2 loader repair technology by the Bureau of technical supervision certification.
Frequency converter in the energy saving application of loading machine
Loader at startup, the current of the motor rated higher than5-6 times, will not only affect the service life of the motor and consumes more energy. The system
was designed in the motor selection will have a certain margin, the motor speed is fixed, but in the actual use of the process, sometimes lower or higher speeds, so the inverter is very necessary. Frequency converter can be realized by changing the motor soft start device, input voltage frequency to achieve energy-saving the purpose of speed, but also can give the device provides overcurrent, overvoltage, overload protection function. Comparison of domestic famous manufacturers such as crystal, British Witten converter.
Development trend of domestic wheel loader
Homemade wheel loader from low level, low quality, low price, to meet the functional model to high level, high quality, price, economic and practical type transition. From the imitation of counterfeit to independent development transition, all the major manufacturers continued to carry out technological inputs, using different technologies, the key parts and the system of technical innovation, from product design, without its own characteristics and advantages of the present situation, from the low level of disorderly competition in the circle talent showing itself, become loader industry leader. (1) large and small wheel loader, in recent years the development process, is subject to objective conditions and the total market demand restriction. The most intense competition in the medium-sized loader update speed will be faster. (2) according to the manufacturer of the actual situation, to design, optimize the performance index, strengthen the structural strength and rigidity, so that the reliability is making strides. (3) refinement of the system structure. As power system damping, a radiating system structure optimization, working device performance and the hinge point of dust, industrial design and so on. (4) the use of electronic technology and the load sensing technology to realize the automatic shift gearbox and hydraulic variable system, improve efficiency, save energy, reduce the operating costs of loading machine. (5) to improve the safety, comfort. Cab gradually have FOPS&ROPS, driving the indoor environment to the car moving in the direction, steering wheel, seat, the handle can be adjusted, so that the operator in the best position to work. (6) reducing noise and emissions, strengthen the environmental protection index. With the enhanced awareness of environmental protection, reduce noise and exhaust emissions of loader work already approach is in eyebrow nimble, now many large city has been developed for motor vehicle noise and emissions standards, construction machinery do not meet emission standards, will be restricted in the area of sales. (7) make extensive use of new materials, new technology, new technology, especially the machine, electrical, hydraulic integration technology, improve product life and reliability. (8) best to simplify the repair to minimize maintenance times and repair time, repair space increases, widespread adoption of electronic surveillance and monitoring technology, further improve the fault diagnosis system, providing the driver troubleshooting method.
In 1, general safety precautions
The driver and the relevant personnel in the use of loader before, must carefully read the manufacturing enterprises provide maintenance manuals or operation maintenance manual, according to the information provision matters to do. It will bring serious heavy fruit and unnecessary loss. The driver should conform to the safety requirements of wear, and wear the necessary protection facilities. During the operation area is smaller or dangerous areas, it must be in the range or dangerous point display a warning sign. The absolute forbidden pilot drunken or excessive fatigue driving operation. In the center hinge area repair or inspection operation, to mount " anti rotating rod" to prevent the front, rear frame relative rotation. And in the loader stop, in a climbing ladder handrail where the upper and lower loading machine. Do not use in loader working or walking to jump up and down. The repair loader needs to lift arm, must take the lift arm pad firmly guarantee repair, in any case, the boom will never fall.
In 2, the engine before starting safety precautions
The check and make sure all the lamps lighting and display lamp can normally display. Especially to check the steering lamp and brake indicating lamp of the normal display. The check and make sure when starting the engine, not someone under the car loader or near areas of work, to ensure that the accident would not endanger themselves or the safety of others. The starting front loader gear control handle should be turned to a neutral position. II with emergency brake braking system, should be the hand brake handle plate into the parking position. The only in the air flow of good places to start or run the engine. As in the indoor operation, to put the engine exhaust port receiving or towards outdoors.
In 3, after the engine is started and the operation safety precautions
1after the engine is started, the brake pressure to achieve the safe pressure again when getting started, to ensure driving safety braking. Emergency brake emergency and parking brake valve button press ( only when the air pressure to allow starting pressure, button can be pressed, or press it will automatically jump ), so that the emergency and parking brake release, to hang I block starts. No emergency brake parking brake handle is only needed to be put down, released into the parking brake can start. The removal of loader in walking on the road to failure, with special attention to iron, obstacles such as ditches, cut a tire. 3mirror adjustment, so that the driver is seated can have the best view effect. The ensure loader horn, backward signal lamp, as well as all the insurance device can work normally. In the beginning or in the steering around flexible in place, should according to the speaker, to warn the surrounding personnel safety first. He started walking in front, to deal with all the operating handle steering wheel, pedal, try again, determined to have been in a normal state to begin to work. Special attention should be paid to check the steering, braking is intact. Determine the steering, braking completely normal, before starting to run. The procession, bucket placed off about 400mm height. In the mountain ramp operations or across the ditch and other obstacles, should
reduce speed, small rotation angle, should pay attention to avoid tipping. When the loading surface on steep slopes begin to slide towards the side, must immediately unloaded, prevent continues to slide down and operations to avoid excessive, excessive tire slippage; avoid two suspended, does not allow of only two rounds to continue operations. Methods for the tractor, allowing only with traction device hanging, towed and loader is allowed between the station, and should keep a safe distance, to prevent the occurrence of safety accidents.
4shutdown safety precautions
The loader should stay on the ground, and the bucket flat on the ground. When the engine is switched off, to be repeated several times a working device control handle, to ensure that the hydraulic cylinder in the resting state without pressure. When the loader can only stop on the ramp, will tire pad. The various handle put in neutral or intermediate position. The first lock keys away, then turns off the power switch, then closes the doors and windows. The no stop in the open fire or high temperature region, to prevent tire heat explosion, cause an accident. The use of combination valve or storage tank for tyre inflation, people may not stand in the front tires, to prevent an explosion