What Is a Crawler Excavator?

Crawler hydraulic excavator is an earthmoving machine that uses buckets to dig materials that are above or below the bearing surface and load them into a transport vehicle or unload to a stockyard. The excavated materials are mainly soil, coal, silt, and pre-loose soil and rock. From the perspective of the development of construction machinery, the development of excavators is relatively fast. As one of the most important construction machinery models in engineering construction, the correct selection of excavators is even more important. Special machinery and equipment widely used in mining and urban and rural construction with advanced performance and unique technology.

The first manual excavator has a history of more than 130 years, during which it has experienced the gradual development process from steam-driven bucket rotary excavators to electric-driven and internal combustion engine-driven rotary excavators and fully-automatic hydraulic excavators using electromechanical-hydraulic integration . Due to the application of hydraulic technology, in the 1940s, it was possible to equip tractors with hydraulic pressure.

Common excavator structures include power units, work units, turning mechanisms, operating mechanisms, transmission mechanisms, walking mechanisms, and auxiliary facilities. From the appearance, the excavator is composed of a working device, an upper turntable and a traveling mechanism. ^[1]

The following is the classification of common excavators: Excavator classification 1: Common excavators are driven by internal combustion engines and electric drives. The electric excavator is mainly used in plateau hypoxia and underground mines and other flammable and explosive places. Excavator classification two: According to different walking methods, excavators can be divided into crawler excavators and wheel excavators. Excavator classification three: According to the different transmission methods, excavators can be divided into hydraulic excavators and mechanical excavators. Mechanical excavators are mainly used in some large mines. Excavator classification four: According to the purpose, the excavator can be divided into general excavators, mining excavators, marine excavators, special excavators and other different types of excavators. . Caterpillar 385B excavator hydraulic excavator is mainly composed of engine, hydraulic system, working device, traveling device and electrical control. The hydraulic system consists of a hydraulic pump, a control valve, a hydraulic cylinder, a hydraulic motor, a pipeline, and a fuel tank. The electrical control system includes a monitoring panel, an engine control system, a pump control system, various sensors, and solenoid valves. According to its structure and application, it can be divided into: crawler, tire, walking, full hydraulic, semi-hydraulic, full swing, non-full swing, general type, special type, articulated type, telescopic arm type and other types. The working device is a device that directly completes the excavation task. It consists of three parts: a boom, a stick, and a bucket. Boom lift, boom extension and bucket rotation are all controlled by reciprocating double-acting hydraulic cylinders. In order to meet the needs of various construction operations, hydraulic excavators can be equipped with a variety of working devices, such as digging, lifting, loading, leveling, clamps, bulldozing, impact hammers and other operating tools. The slewing and walking device is the body of a hydraulic excavator. The upper part of the turntable is provided with a power device and a transmission system. The engine is the power source of the hydraulic excavator. Most of the diesel engines are used at convenient locations. Electric motors can also be used instead. The hydraulic transmission system transmits the power of the engine to the hydraulic motor, hydraulic cylinder and other actuators through the hydraulic pump, and pushes the working device to complete the work. ^[1]

The purpose of carrying out regular maintenance on the excavator is to reduce the failure of the machine and prolong the service life of the machine; shorten the downtime of the machine; improve the work efficiency and reduce the operating cost. By managing fuel, lubricants, water, and air, you can reduce failures by 70%. In fact, about 70% of failures are caused by poor management. ^[1]

1. Reasonable selection of hydraulic oil (1) Hydraulic oil viscosity The principle for determining the viscosity of hydraulic oil is that the hydraulic oil viscosity (for components such as pumps and motors) is in the range (16- 36x10-6mm2 / s); short-term cold start viscosity corresponding to ambient minimum temperature 1000X10-6mm2 / s; and viscosity corresponding to short-term allowable leakage oil temperature at 90 ° C 10X10-6mm2 / s. (2) Viscosity index (VI) This index directly reflects the nature of oil viscosity changes with temperature (ie, the viscosity-temperature characteristics of oil). The viscosity index of oil is higher, indicating that the viscosity of this oil varies with temperature. The degree of change is small; otherwise, it is large. The viscosity index of anti-wear hydraulic oils from well-known foreign manufacturers (such as Mobil, Shell, etc.) are VI 110, and the viscosity index of domestic advanced anti-wear hydraulic oils is about VI = 95. The viscosity index of high-viscosity index hydraulic oil (HV) and multi-stage engine oil produced abroad is VI> 140. This point must be paid special attention to users who use large imported hydraulic excavators and use domestic hydraulic oil (or use engine oil as hydraulic oil). Reducing the viscosity index will reduce the ambient temperature range to which the oil is adapted. If it is not possible to use it, you should consult the oil manufacturer for relevant information. You must make appropriate adjustments to the use range of the oil, and if necessary, change the relevant settings of the equipment ( (Such as extreme temperature, etc.). (3) Other comprehensive performance Because the working pressure of the modern large hydraulic excavator hydraulic system is high (32MPa), the working oil temperature of the hydraulic oil is also allowed to be high (about 90 ° C), so in order to ensure the normal oil change cycle For the hydraulic system to work properly, the lubricity, oxidation stability, abrasion resistance, rust and corrosion resistance, anti-emulsification,

Operation technology

First check the surrounding conditions. When turning, make sure that you know the surrounding obstacles and terrain safely. During the operation, check the forward and backward directions of the track to avoid tipping or impact. Try not to face the final drive in the direction of digging, otherwise it will be easily damaged.

1. The excavator is a fixed asset with large economic investment. In order to increase its service life and obtain greater economic benefits, the equipment must be assigned to people, machines and positions, and responsibilities must be clear. When the job must be transferred, the equipment should be handed over. 2. After the excavator enters the construction site, the driver should first observe the geology of the working face and the surrounding environment. There must be no obstacles within the excavator's rotation radius to avoid scratching or damaging the vehicle. 3. After the machine is started, no one is allowed to stand in the bucket, on the shovel arm and on the track to ensure safe production. 4. During the work of the excavator, no one is allowed to stay or walk within the turning radius or under the bucket. Non-drivers are not allowed to enter the cab and move around, and they are not allowed to train the driver to avoid damage to electrical equipment. 5. When the excavator is shifted, the driver should observe and whistle first, then shift to avoid safety accidents caused by people at the machine. . 6. After the work is finished, the excavator should be moved away from the low-lying place or the edge of the trench (ditch), parked on flat ground, closed the doors and windows and locked. 7. The driver must do the daily maintenance, overhaul, and maintenance of the equipment, make daily records of the equipment in use, find that the vehicle has a problem, and cannot work with illness, and report it for repair in a timely manner. 8. The driver's cabin must be clean and tidy, and the surface of the vehicle body must be clean, free of dust and oil; develop the habit of wiping the car after work. 9. The driver should make daily records of the day shift, make statistics on the work content of the day, and complete the formalities for the odd jobs or zero items outside the project in time, and make a record for the checkout. 10. Drivers are strictly prohibited from drinking and driving at noon during work. If found, financial penalties will be imposed and the economic losses caused will be borne by me. 11. For man-made vehicle damage, analyze the cause, find the problem, distinguish the responsibilities, and carry out economic punishment according to the severity of the responsibility. 12. We must establish a high sense of responsibility, ensure safe production, do a good job of communicating and serving with the founder, do a good job of bilateral relations, establish a good working style, and work hard for the development and effectiveness of the enterprise. ^[1]