The whole wheel loader is mainly composed of power system, transmission system, working device, working hydraulic system, steering hydraulic system, frame, operating system, braking system, electrical system, cab, cover, air conditioning system, etc. The working principles of the first five systems are described in detail below.
Concise analysis of the working principle of wheel loader
The whole wheel loader is mainly composed of power system, transmission system, working device, working hydraulic system, steering hydraulic system, frame, operating system, braking system, electrical system, cab, cover, air conditioning system, etc. The working principles of the first five systems are described in detail below.
1. Power system
The power system of the loader consists of the power source diesel engine and the auxiliary systems that ensure the normal operation of the diesel engine, mainly including the diesel engine, fuel tank, throttle control assembly, cooling system, fuel pipeline, etc. The diesel engine completes the normal walking function through the dual-variable drive transmission system; drives the working device to complete the working actions such as scraping, lifting, and tipping by driving the working hydraulic system; and completes the steering action by driving the steering hydraulic system and deflecting the frame.
2. Transmission system
The transmission system consists of torque converter, gearbox, drive shaft, front and rear drive axles and wheels. Through the automatic adjustment of the output torque and speed through the transmission system, the loader can automatically change the speed and traction according to the road conditions and resistance to adapt to the changing working conditions. After the gear is engaged, it can automatically and continuously shift from the start to the maximum speed of the gear, with a smooth start and good acceleration performance. In the event of a gradient or sudden road obstacle, it can automatically decelerate to increase traction and drive at an arbitrarily small speed without shifting gears to overcome obstacles. After the external resistance is reduced, it can quickly increase the speed automatically to improve the operation rate. When shoveling materials, it can cut into the material pile at a high speed and automatically decelerate as the resistance increases to improve the traction force of the wheel side to ensure the cutting.
The power output by the engine is transmitted to the gearbox through the torque converter, and through the speed change of the gearbox, the specific speed is driven by the drive shaft to drive the front and rear axles and the wheels to rotate to achieve the function of walking at a certain speed.
3. Working device
The working device of the loader is composed of four parts: bucket, boom, rocker arm and tie rod. The boom is a single-plate structure, the rear end is supported on the front frame, the front end is connected to the bucket, and the middle part is connected to the boom cylinder. When the boom oil cylinder is extended and retracted, the boom is rotated around its rear end pin to realize the lifting or lowering of the bucket. The rocker arm is a single rocker arm mechanism, and the middle part is connected with the boom arm. When the bucket oil cylinder is extended and retracted, the rocker arm is rotated around its middle support point, and the bucket is turned up or down through the pull rod.
Scope of application of wheel loader
Years of production practice at home and abroad have proved that wheel loaders are suitable for the following aspects:
1. It is used for loading, pushing and dumping, lifting and traction in the construction of open-pit mine development and stripping, railway foundation building and road paving.
2. In small and medium-sized open-pit mines, it is used to replace excavators and automobiles as the main mining, loading and transportation equipment of mines; it can be operated in conjunction with automobiles, and can also be used to transport ore to the crushing station.
3. In some large-scale open-pit mines, excavators are used to carry out mining and loading work and other auxiliary operations under complex conditions (such as sorting mining, end of working face, blasting and dispersing, digging trenches, etc.).
4. It can be used for combined mining, loading and transportation operations on working faces with large slopes to complete difficult mining work.
The common tire type and crawler type front loader have their own characteristics. Although the crawler-type front loader has large traction and shoveling force, and has better off-road and climbing performance, it has low speed and inflexibility. Sometimes a trailer is required to transfer the job site, and the construction cost is high. Therefore, crawler-type front-loaders are rarely used in open-pit mines. The tire-type loader is the most commonly used in mines around the world, so its production quantity is large, and its production technology has developed rapidly. The largest model has a bucket capacity of 40m3.
Advantages and disadvantages of wheel loaders
In open pit mines with suitable conditions, the use of wheel loader can highlight the following advantages:
1. The tire-type front loader has fast walking speed, short working cycle time and high loading efficiency. According to the mine calibration data, the front-mounted machine with a bucket capacity of 5~8m3 can reach a speed of more than 35km/h, which is 30~90 times faster than that of an electric shovel. It only needs 40~45 times per working cycle, and the average production capacity of each shift can reach 3500. ~4000t, the average labor productivity can be increased by 50%~100%.
2. The self-weight of the tire-type front loader is relatively light, which is equivalent to 1/8~1/6 of the mass of the excavator with the same bucket capacity. It saves a lot of steel, and the manufacturing cost is only 1/4~1/3 of the excavator. The machine is cheap, which can reduce the investment in the production equipment of the mine and reduce the proportion of fixed assets.
3. The tire-type front loader has strong climbing ability and good maneuverability. It can carry out loading operations on the slope working surface that is not allowed by the excavator, especially in the newly built mine site that lacks electricity, which can speed up the operation. Mine development and construction and shorten the construction period.
4. The depreciation period of the tire-type front loader is only 1/4~1/8 of the excavator, and the new and more advanced equipment can be replaced after 5~6 years of operation, which is convenient for mine management and maintenance work, and is conducive to the replacement of equipment. .
5. The tire-type front loader is easier to operate than the excavator, so it can shorten the driver training time. At the same time, a loader only needs one driver to operate, which can save manpower, material and financial resources.
However, compared with excavators, front loader also has some disadvantages in production:
(1) The digging capacity of the tire-type front loader is smaller than that of the excavator. When the blasting quality is not good and there are many large blocks, its work efficiency will be significantly reduced; for the viscous materials, it needs to be loosened before shoveling operations and other assistance. Operation.
(2) Compared with the excavator, the size of the working mechanism of the front loader is smaller; due to the limitation of safety conditions, it is not suitable to work on the working face with a higher blasting heap, and the height of the stope steps should generally not exceed 12m.
(3) The tires of the loader wear faster and have a shorter service life. In recent years, although measures such as adding protective chain rings or adopting pad-type track shoes have been adopted to reduce tire wear, the tire life is only about 1500h, and the tire cost still accounts for a large proportion of the production equipment cost (about 40%). %~50%, even as high as 60%).