The application methods of loaders in highway engineering

The basic operation process of a loader is loading, transferring, unloading and returning. Different operation methods should be selected according to the different objects of construction work. This article focuses on introducing the application skills of loaders in highway engineering.

Load loose materials such as crushed stones and sand

In highway engineering, loaders are currently mainly used to shovel various loose materials such as crushed stones and sand in mixing plants. When loading and unloading, a straight toothed bucket should be used. First, place the bucket at the bottom of the material pile, with the bucket opening facing forward. The machine moves at a low speed, and the bucket teeth are inserted into the material pile. If the loading resistance is relatively large, the boom can be operated to make the inclined bucket vibrate up and down. This can reduce the frictional resistance between the material particles, accelerate the speed at which the material enters the bucket, and continue until the bucket is full. Then retract the bucket with the bucket opening facing upwards. Use the boom to raise the bucket to a transfer position about 50cm above the ground. Reverse the machine and drive it to the unloading area.

2. Shovel the soil below the machine's surface

In highway engineering, a loader can be used to strip the surface soil. At this time, the loader should adopt a straight-blade bucket, similar to the operation of a bulldozer. When loading, first lower the bucket and rotate it to form a certain shovel Angle (10-30°) with the ground. For grade I and II soil, the shovel Angle can be larger; for grade III and above soil, it can be larger; and for grade III and above soil, it should be smaller. Then the machine moves forward in I gear, allowing the bucket blade to cut into the soil. The depth of the cut is generally maintained at about 15 to 20cm. For difficult-to-shovel soil, to reduce the resistance of the shovel loading, the boom can be operated to make the bucket vibrate up and down or slightly change the shovel Angle until the bucket is full. After filling it with materials, put it in the hopper. Lift the bucket to the transportation position, drive it away from the working face and transport it to the unloading area. This method is also often used for collecting river sand and can be applied to the leveling of work sites.

3. Shovel the soil pile

At present, for the construction of lime-lime soil base, stone-mixed stabilized soil is often used. When mixing stabilized soil, a loader can be used to load the soil pile. When shoveling and loading, the following three different methods can be adopted according to the conditions of soil accumulation and the differences in the operation skills of the driver.

(1) Layered shovel loading method

Lower the bucket close to the bottom of the slope, face the mound, and move forward at a low speed. When the bucket is inserted into the soil pile to a certain depth, it is lifted in coordination with the boom. After the bucket teeth leave the soil pile, turn the bucket to the transportation position. This operation method has low insertion resistance and the operation is relatively stable because the insertion is not deep and there is a lifting action to cooperate after insertion. In addition, due to the longer loading surface, a higher filling coefficient can be achieved. Because of its characteristics, it is similar to the operation method of a front shovel excavator. Therefore, it is also called the excavator shovel loading method.

(2) Segmented shovel loading method

When operating, tilt the bucket slightly forward and insert it from the bottom of the slope. After it has been inserted to a certain depth, lift the bucket. When the engine speed drops, disengage the clutch to restore the engine speed. During the process of restoring the rotational speed, the bucket will continue to rise and load some soil. After the rotational speed is restored, proceed with the second insertion. Repeat this process until the bucket is filled up or the bucket is raised above the working surface. Sometimes, after the bucket is fully filled, it is still slightly pushed towards the working surface to loosen the soil, which is conducive to the next loading. This method is suitable for environments with relatively hard soil. Its characteristic is that it can keep the engine operating at the rated condition all the time, enhancing the working capacity. However, the insertion and lifting operations carried out in sequence by relying on the bucket are rather complicated, causing the driver to get tired easily and the clutch to wear out frequently.

(3) Cooperate with the shovel loading method

First, lower the bucket to the bottom of the slope. While the loader is moving forward, carry out the loading operation in coordination with the actions of turning the bucket or lifting the boom. That is, when the bucket is inserted into the material pile to a depth of about 0.2 to 0.5 buckets, while the loader is moving forward, intermittently operate the bucket to flip up and lift it in coordination with the boom until the bucket is full. After the bucket teeth leave the soil pile, turn the bucket to the transportation position. By using the combined loading method, the bucket does not need to be inserted very deep. By the coordination of the insertion movement, the rotation of the bucket teeth and the lifting movement, the insertion resistance is greatly reduced and the bucket is also easy to fill. However, it requires drivers to have a relatively high level of operational skills.

The above three methods are not feasible. During operation, it is necessary to always pay attention to cleaning the soil adhering to the inside and outside of the bucket. Otherwise, it will not only affect its effective capacity but also increase the resistance of the operation.

4. Clear the earthwork and stonework at the blasting site

In the earthwork blasting project of roadbeds, loaders (or excavators) are commonly used to clear the blasting site. When using a loader for cleaning, it is advisable to switch to a V-shaped toothed bucket to enhance its loading and digging capabilities. When cleaning, the particle size of the crushed stones after blasting must not exceed the allowable capacity of the bucket. If it does, the stone materials need to be blasted again. In addition, when the cleaning distance is within 40 to 100 meters, the loader can shovel and transport by itself. However, when the transportation distance exceeds 100 meters, it needs to cooperate with the dump truck. After the cleaning is completed, the loader should be moved and parked outside the blasting warning line to ensure the safety of both the personnel and the machine.

5. Lift various operation tools and equipment

At the construction site of highway engineering, if there are no dedicated lifting devices, various operation tools and equipment can be lifted by using loaders. For instance, when it is necessary to repair or assemble a certain construction machinery at the construction site, a loader is a lifting device that can be used to disassemble and assemble various components. When using a loader as a lifting device, the lifted heavy object must be securely fastened. The steel wire rope or hook should be hung between the teeth of the loader bucket, and the center of the heavy object must be at the same vertical position as the center of the bucket. When operating, there should be a dedicated person to direct. The driver should operate carefully. When lifting, the bucket should be retracted first and then the boom should be raised slowly. When assembling, it should be placed slowly and gently. Meanwhile, the lifting capacity of the loader should be greater than the weight of the lifted object to ensure the safety and reliability of the lifting operation and prevent damage to personnel and mechanical equipment.