How does a Loader Work?

To most of us, the loader is a strange machine. But for the mechanic and the loader driver, their job is to deal with the loader every day. So it is necessary for them to know and understand the device. And for me in our non-professional staff, a little understanding is also beneficial. So, let me introduce the loader!

1.A brief introduction to the loader

Loaders, including engines, torque converter, gearbox, front and rear drive axle, referred to as the four large, is a widely used in highway, railway, construction, hydropower, port, mining and other construction projects earthwork construction machinery. It is mainly used for shoveling and loading loose materials such as soil, sand, lime and coal. Different auxiliary devices can also be installed for earth moving, lifting and other materials such as wood loading and unloading operations. In road construction, especially in high-grade highway construction, the loader is used for subgrade engineering filling and excavation, asphalt mixture and cement concrete yard aggregate and loading operations. In addition, it can also be used for pushing soil, scraping the ground and pulling other machinery.

Because the loader has the advantages of high speed, high efficiency, good mobility and light operation, it has become one of the main types of earthwork construction machine. China's loader industry after nearly 50 years of development, especially in the past 10 years of ultra-high speed development, product quality has been greatly improved, and the gap between the world's advanced level has become smaller and smaller, has been the world market, including the most demanding European and American markets widely recognized.

2.The operation of a loader

Loader operation can be divided into five parts, the following is the specific introduction.

· Scoop up and forward tilt

The folding and forward tilting of the bucket are realized by the working circuit of the rotary bucket hydraulic cylinder. When the manual reversing valve 3 is operated to make it work in the right position, the piston rod of the bucket hydraulic cylinder extends out and drives the bucket to be flipped and folded by the rocker bucket for shovel installation.

· Lift the arm

The lifting of the movable arm is realized by the working circuit of the hydraulic cylinder of the movable arm. When the manual reversing valve 11 is manipulated to work in the right position, the piston rod of the boom lifting hydraulic cylinder is extended to push the boom up and complete the boom lifting action.

· Transfer machine articulated frame bending steering

Wheel loader's frame USES the front and rear car hinge mechanism, so its steering mechanism USES the hand-over frame for bending steering. The bent steering process of loader articulated frame is realized by the working circuit of hydraulic cylinder and requires stable steering speed. The oil of the steering hydraulic cylinder is mainly from the steering hydraulic pump 17. Under the rated speed of the engine, the flow rate of the steering hydraulic pump is 77L/min. When the engine is affected by other loads and the speed drops, the stability of the steering speed will be affected. At this time, it is necessary to fill the reduced flow of steering pump 17 from auxiliary hydraulic pump 1 through flow reversing valve 18 to ensure the stable flow of steering oil circuit. When the flow reversing valve 18 is in the corresponding position, the excess or all the hydraulic oil of the auxiliary hydraulic pump can be fed to the oil circuit of the working device to accelerate the action speed of the lifting hydraulic cylinder and bucket hydraulic cylinder of the moving arm, shorten the operation cycle time and improve the production efficiency.

· The shift

The working principle of gear shifting: the piston at the end of the accumulator is installed in the piston cylinder, the right end of the spring is on the top, and the right end of the spring of different sizes is on the boss of the main pressure valve and the shell respectively. An oil chamber is formed between the left end of the piston and the screw plug at the end, and is communicated with the connected oil channel of the reversing valve through the oil channel. One-way valves and throttles are fitted on this section of the oil path. When shifting gears, the hydraulic pressure of the oil circuit flows into the oil cylinder of the shifting clutch, thus reducing the oil pressure in the oil circuit. The oil chamber of the accumulator is replenished with oil fluid through a one-way valve, so that the brake or clutch can be quickly combined. Because the oil chamber of the oil flow out at the same time, under the action of the main pressure valve control oil duct, the valve stem left the oil pressure in the system, when the main, platen tiejin, stop moving oil cylinder, the oil pressure rise, - part of the oil through the orifice flow oil chamber, pressure is mounting on the oil chamber, push the piston moves to the right, compression spring Ze, main pressure valve stem moves to the right, this system's oil pressure was increased, the master and slave unit in combination with a smooth, smooth can shift.

· Automatic limit device

In order to improve the production efficiency and avoid the frequent opening and closing of the safety valve caused by the piston of the hydraulic cylinder reaching the limit position, the automatic limit device is installed on the working device and the reversing valve to realize the automatic leveling of the bucket in the work. The automatic limit stroke switch is installed at the rear hinge point of the moving arm and the hydraulic cylinder of the rotating bucket. When the moving arm is lifted to a high position or the bucket is lowered to the best level with the stopping surface, the contact touches the travel switch and sends out a signal to make the solenoid directional valve move 8 to make it work in the right position. At this time, the pneumatic system is connected to the ventilation circuit, and the compressed air in the air storage cylinder enters the end of the reversing valve 11 or 3, and the bouncing positioning steel ball is released. The valve core then returns to the center position under the action of the spring, the hydraulic cylinder stops the action. When the travel switch off the contact, the solenoid directional valve power off and make it return to the normal position, then the air inlet channel is closed, the compressed air in the valve body from the vent.