LOADER
Basic Information
The main function of the wheel loader is to shovel and transport loose materials over short distances. It is one of the models with the fastest development, the largest production and sales volume and the largest market demand in construction machinery. We usually see the wheel loader the most, as opposed to the crawler loader. Compared with the crawler type, it has the advantages of good maneuverability, no damage to the road surface, and convenient operation. Therefore, wheel loaders are widely used.
working principle
basic structure
The schematic diagram of the overall structure of the wheel loader is shown in the “Schematic Diagram”. The loader is generally composed of a frame, a power transmission system, a traveling device, a working device, a steering brake device, a hydraulic system, and a control system. The power of the engine 1 is transmitted to the gearbox 14 through the torque converter 2, and then the gearbox transmits the power to the front and rear axles 10 through the transmission shafts 13 and 16 respectively to drive the wheels to rotate. The internal combustion engine power also drives the hydraulic pump 3 to work through the transfer case. The working device consists of a boom 6, a rocker arm 7, a connecting rod 8, a bucket 9, a boom hydraulic cylinder 12 and a rocker arm hydraulic cylinder 5. One end of the boom is hinged on the frame, and the other end is installed with a bucket. The lifting and lowering of the boom is driven by the boom hydraulic cylinder, and the overturning of the bucket is realized by the bucket hydraulic cylinder through the rocker arm and the connecting rod. The frame 11 is composed of two parts, front and rear, and the middle is connected by a hinge pin 4. By means of a steering hydraulic cylinder, the front and rear frames can be relatively rotated around the hinge pin to realize steering. [1]
principle
As can be seen from the overall structure of the loader, the loader can be divided into: power system, mechanical system, hydraulic system, and control system. As an organic whole, the performance of the loader is not only related to the performance of the mechanical parts of the working device, but also related to the performance of the hydraulic system and the control system. Power system: The motive power of the loader is generally provided by the diesel engine. The diesel engine has the characteristics of reliable operation, hard power characteristic curve, and fuel economy, which meets the requirements of the loader under harsh working conditions and changing loads.
Mechanical system: mainly includes walking device, steering mechanism and working device. Hydraulic system: The function of this system is to convert the mechanical energy of the engine into the hydraulic energy by using the oil pump as the medium, and then transmit it to the oil cylinder, oil motor, etc. to convert it into mechanical energy. Control system: The control system is a system that controls the engine, hydraulic pump, multi-way reversing valve and actuator. The hydraulic control drive mechanism is a device that converts the electrical or mechanical energy of small power into hydraulic energy and mechanical energy of powerful power in the hydraulic control system. It consists of hydraulic power amplification components, hydraulic actuators and loads, and is the core of static and dynamic analysis in hydraulic systems.Advantages and disadvantages
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. Each working cycle only takes 40~45s, 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 light, which is equivalent to 1/8~1/6 of the mass of the excavator with the same bucket capacity, which saves a lot of steel. The manufacturing cost is only 1/4~1/3 of the excavator. Excavators are cheap, which can reduce the investment in mine production equipment 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. It can be replaced with new and more advanced equipment after 5 to 6 years of work, 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 material with strong viscosity, it needs to be loosened before shovel loading and other operations can be carried out. Auxiliary work.
(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 pile, and the height of the stope steps should generally not exceed 12m.
(3) The tires of the front 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%).
Scope of application
Years of production practice at home and abroad have proved that wheel 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. [2]
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 construction and road construction.
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 the mine; it can be combined with automobiles, and can also be used to transport ore to the crushing station.
3. In some large open-pit mines, cooperate with excavators 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
