There are many kinds of working devices of hydraulic excavator. At present, backhoe and crushing hammer are most used in engineering construction.
Articulated backhoe is the most commonly used working device of hydraulic excavator. It is hinged with main components such as boom, stick and bucket. Under the action of hydraulic cylinder, each component rotates around the articulated shaft to complete excavation, lifting and dumping.
1. Boom
Boom is the main component of excavator working device. At present, integral boom is widely used. Combined boom is used in complex and changeable working conditions, and now it is generally used as a special configuration.
The integral boom has the advantages of simple structure, small mass and large stiffness. Its disadvantage is that there are few replaceable working devices and poor universality. It is mostly used on excavators with similar long-term operating conditions.
The integral boom can be divided into straight boom and curved boom. The straight boom has the advantages of simple structure, small mass and convenient manufacture. It is mainly used for suspended hydraulic excavator, but it can not obtain large excavator depth, so it is not suitable for general excavator. At present, the curved boom is the most widely used structural form. Compared with the straight boom of the same length, it can obtain a larger excavation depth, but the unloading height is low, which is in line with the operation requirements of the excavator.
2. Stick
The main function of the stick is to connect the boom and bucket, increase the operation range of the excavator and coordinate the center of gravity of the whole machine. The stick cylinder is mainly used for excavation. Under the working conditions of mine or hard soil, the stick can be used to improve the work efficiency. In order to meet the requirements of different working conditions, the overall dimensions of the stick can be changed. For example, the extended stick can meet the needs of underwater cleaning, etc. Under high-strength conditions, stiffeners can be added to the stick or the length of the stick can be shortened to ensure its strength and strength.
3. Bucket
(1) Basic requirements
The longitudinal section shape of the bucket shall adapt to the movement law of various materials in the bucket during excavation, and be conducive to the flow of materials and filling the bucket, so as to minimize the loading and unloading resistance. The bucket teeth can increase the linear specific pressure of the bucket on the excavated materials. Bucket teeth and bucket shape parameters shall enable them to have small unit cutting resistance, which is easy to cut into and destroy the soil. Bucket teeth shall be wear-resistant and easy to replace. In order to prevent the material loaded into the bucket from falling out, the ratio of bucket width to material diameter shall be greater than 4 / 1. In this way, the material is easy to unload, which can shorten the unloading time and improve the effective volume of the bucket.
(2) Bucket structure
Bucket shape and size are closely related to its operation object. In order to meet the needs of various excavation operations, the same excavator can be equipped with buckets of various structural forms. The assembly forms of bucket teeth include rubber snap pin type and bolt connection type.
The structural types of the connection between the bucket and the hydraulic cylinder include four-bar mechanism and six bar mechanism. The connection mode of the four-bar mechanism is that the bucket is directly hinged with the hydraulic cylinder, so that the bucket angle is small and the working torque changes greatly. Under the condition of the same stroke of the piston rod of the hydraulic cylinder, the bucket can obtain a large angle.