The hottest new development of foreign wheel loade

New progress of foreign wheel loaders

Guide: due to the continuous progress of technology, performance and application scope of wheel loaders. The reliability, mobility and adaptability of loading hard materials have been recognized by people, and have become the main loading equipment of construction projects and open-pit mines. Currently developed abroad

due to the continuous progress of technology and performance of wheel loaders, the application range of

continues to expand. The reliability, mobility and adaptability of loading hard materials have been recognized by people, and have become the main loading equipment of construction engineering and open-pit mines. At present, some large wheel loaders have been developed abroad, which have the characteristics of advanced structure, superior performance and high automation level. In the 21st century, automatic and intelligent wheel loaders with higher efficiency, lower cost, more convenient maintenance and better comfort will be introduced to the market

l new products are constantly introduced. In recent years, wheel loaders continue to develop towards large-scale and miniaturization, focusing on improving the efficiency and reducing costs, and constantly promote new products and accelerate the upgrading. Caterpillar launched the cat966f wheel loader in the early 1990s, and then launched the cat980f wheel loader after a year. It increased the bucket capacity and power, improved the performance and reliability. Soon

launched a larger cat994 wheel loader, which is equipped with a m3 bucket according to the volume and mass of materials, with a machine weight of 170t; The

cat3516 diesel engine with turbocharged aftercooling has large traction and good acceleration performance; The extended working

boom increases the unloading height and can load the large dump truck with a load capacity of z18t. Marathon Letourneau company launched L1400 and l1800 wheel loaders on the basis of li100 in 1990 and 1994 respectively. In September, 1998, at the 2000 Annual Conference of

loagding held in Tucson, the company announced that it was developing the Dourong 20

4m3 will be put on the market at the beginning of the 21st century for loading by dump trucks with a capacity of

150 -200t. Dresser launched the 4000 wheel loader in the early 1990s, with a bucket capacity of M3 and a machine weight of 151

8t, transmission system with modular structure, high-power, sensitive button controlled

hydraulic system, Z-type single rocker arm working device, optimized overall structure and wet disc

brake, with automatic adjustment and automatic sealing performance. At present, there are about 400 large wheel loaders (with a power greater than 750kW) in the world, which are used in open-pit mines and construction projects, together with large dump trucks. While developing large wheel loaders, micro wheel loaders have won the market with flexibility, high efficiency, multi-function and low price. For example, the bucket capacity of fl30-l wheel loader produced by Japan Guhe company is 0.34m3, and the machine weight is 2.3t; Wa30-l bucket of Komatsu

company has a capacity of 0.34m3 and a diesel engine power of 20kW; Toyota weaving machine company's bucket capacity is 0.17m3, machine weight is 1t, etc. These micro loaders are suitable for trenching, leveling and stacking in construction sites and underground mines

2 new structures continue to emerge

2.1 working mechanism

caterpillar launched a combined eight bar mechanism, which has the characteristics of parallel movement from the ground to the entire lifting height range. It designs the quick connector and tower type

mechanism into an integral working device, and completes the operations of loading and unloading, stacking, snow sweeping, leveling, road cleaning, bulldozing, hoisting, transportation and surface drilling by quickly replacing different auxiliary mechanisms

, so as to realize multiple functions of one machine and reduce the investment of user equipment. Dreiser company develops Z-type single arm working mechanism and combines it with high-pressure hydraulic system to provide greater digging force for the bucket; Shorten the loading cycle, increase the

bucket fill factor, and greatly improve labor productivity. Because there are fewer hinge points and fewer rods, it is easy to maintain and reduce the maintenance cost

2.2 transmission mechanism

the wheel loader represented by caterpillar adopts a hydro mechanical transmission system, and its automatic power shift gearbox automatically selects the gear transmission ratio, so that the gear shift is carried out at the best efficiency point of the gearbox. The stic (steering

speed change integration) system recently launched by the company integrates the steering and shift functions on a joystick,

makes the operation more labor-saving

light, the shift more stable, and can greatly improve productivity. The wheel loader represented by wa series small and medium power (less than 125KW) of Komatsu company in Japan adopts a new centralized drive axle. It concentrates the main drive, brake and planetary wheel final drive in the middle of the axle, the cross-section of the axle housing changes continuously and gently, and the internal stress distribution is reasonable, which fundamentally prevents the stress concentration fracture of the bearing section supported by the traditional structure axle housing at the wheel edge. The wheel end adopts floating seal structure, which is easy to install. It has automatic compensation function and good sealing performance. The structure has reasonable design, few basic parts, good processability, good performance and high reliability. The wheel loader of marathon letoole

company adopts diesel engine generator electric wheel transmission, which is simpler than the hydraulic mechanical transmission system. During the whole operation, the diesel engine operates at a constant speed

to reduce fuel consumption and prolong engine life; There are no gearbox, transmission shaft and many other components, which improves the transmission efficiency, convenient operation and maintenance, and low cost; The independent electric traction motor is solid-state control, which reflects that the wire change experimental machine of Jinan new era Gold Testing Instrument Co., Ltd. is to quickly reduce wheel slip and excessive tire wear on the original basis; An electric retarder is set to stop the

machine without working brake, and the loading alignment is accurate; The whole machine has low center of gravity, good driving stability and high reliability

2.3 hydraulic system

Dreiser's wheel loader hydraulic system uses a sensor to receive the diesel engine

speed signal. When the speed drops, the plunger variable displacement pump will automatically increase the flow of the steering system

to maintain a constant steering speed. In the maximum excavation condition, it can reduce the flow

and slow down the action of hydraulic components, so as to ensure that not only the technical difficulties are solved theoretically, but also the dynamic balance of the hydraulic system is maintained, Reduce the heat loss of the hydraulic system and save power. Caterpillar wheel loader steering hydraulic system uses a load transmission

sensitive overflow valve to make the hydraulic pump overflow under the pressure determined by the load, reduce the system pressure

force, and improve the service life of hydraulic components. The hydraulic system of the working device adopts the lifting limit

device and the lowering automatic positioning device, which avoids the high pressure and impact at the end of the hydraulic cylinder stroke during the mechanical limit; The installed accumulator can absorb the impact load and damp the longitudinal swing of the whole machine; There is a triple seal at the guide sleeve of the hydraulic cylinder to prevent leakage and dust

2.4 cab

the design of the cab of the new wheel loader fully considers the physiological needs of people. The arrangement of instrument positions, operating handles and pedals, driver seats, visibility, noise prevention and vibration isolation, temperature regulation, etc. are in line with ergonomics, so that the driver can operate in a comfortable, relaxed and safe environment and improve work efficiency. For example, the cab of caterpillar

wheel loader is equipped with microcomputer monitoring device and adjustable suspension seat,

pilot hydraulic valve operates the bucket control handle and flow amplification steering system, which makes the operation of

portable and flexible, and adopts rollover protection structure (ROPS) and falling body impact protection structure (FOPS) to meet the requirements of ISO standards

3 the continuous improvement of automation level

the breakthrough of microelectronic technology has created conditions for the development of automatic control of wheel loaders, condition monitoring and remote control technology within the scope of vision. Diesel engine <2. The thickness of the test piece shall be measured after cooling/p> Great progress has been made in the automatic control of the oil injection system of the

machine, the automatic control of the gear shift of the gearbox, the performance parameters and the state monitoring. The remote control operation in the line of sight has entered the practical stage, which improves the performance, improves the reliability, shortens the downtime, increases the production capacity, reduces the fuel consumption, and achieves greater economic benefits

3.1 diesel engine automatic control fuel injection system

caterpillar cat994d loader adopts cat3516b diesel engine

engine, which is equipped with HEUI electronic control fuel injection system. According to the external load, the effective control power

and speed, the engine fuel injection pump acts with the governor to accurately adjust the fuel

section, pressurize and supply oil, reduce the initial fuel injection rate, reduce NOx and HC, and the noise is

, High fuel efficiency

3.2 automatic shift of gearbox

kld97zlll wheel loader of Kawasaki Heavy Industry Co., Ltd. in Japan adopts a gearbox that automatically controls the shift from the light weight of the vehicle to the bright spot. It can automatically select the best gear

according to the operating conditions of the loader, and use a microcomputer to control the clutch, so as to simplify the operation, improve the operation efficiency, reduce the impact of

and realize smooth shift; Electronic control devices, sensors, etc. can be used

. Once the control system

fails, manual gear shifting can be used without affecting the work

3.3 equipment condition monitoring

the electronic monitoring (EMS) system developed by caterpillar warns and displays the failure or potential problem of the main system of the wheel light loader. There are three different warning levels and signals, and each signal indicates the state of the system and the appropriate measures that the driver should take

3.4 airborne electronic weighing system

at present, many large wheel loaders are equipped with airborne electronic weighing system

system, which can clearly display the amount of materials to be reloaded, so as to make people know well, so as to prevent overload or underload, reduce the number of invalid sports cars, save working time, and improve the production efficiency. It can also calculate the cumulative mass, and the display instrument displays

in color digital display, which is clear and easy to calibrate, and the error is within T3%

3.5 remote control operation within visual range

cat992c wheel loader of sierrita mine in the United States is equipped with the radio remote control system within visual range developed by

tomation company, which can realize safe operation in dangerous areas such as steep slopes. With the breakthrough of micro processing machine and the expanded application of global positioning system (GPS), there is no doubt that driverless wheel loaders will be developed for construction projects. (Zhao

Yudong)