The Development of Excavators in 20th Century (2)

4. Update design theory, improve reliability and prolong service life. The United States, Britain, Japan and other countries promote the use of finite life design theory to replace the traditional infinite life design theory and method, and combine fatigue damage accumulation theory, fracture mechanics, finite element method, optimization design, and computer-controlled electro-hydraulic servo fatigue. Advanced technologies such as test technology and fatigue strength analysis method are applied to the strength research of hydraulic excavators, which promotes the high quality, high efficiency and competitiveness of the products. And all the nesscceary engine rebuild kits can be found in the market easily. 

The United States proposed a dynamic design analysis method to assess dynamic strength, and created a theory for predicting product failure and renewal. Japan has formulated the strength evaluation procedure of hydraulic excavator components(including cooling system, lubrication system), and developed the reliability information processing system. Under the guidance of the above basic theory, with the help of a large number of experiments, the research cycle of new products has been shortened, the process of upgrading hydraulic excavators has been accelerated, and its reliability and durability have been improved. For example, the operation rate of hydraulic excavators reaches 85% to 95%, and the service life exceeds 10,000 hours.

5. Strengthen labor protection for drivers and improve their working conditions. The hydraulic excavator adopts a cab with a falling object protection structure and a tipping protection structure, installs an adjustable elastic seat, and uses sound insulation measures to reduce noise interference.

6. Further improvements to the hydraulic system. The hydraulic system of medium and small hydraulic excavators has an obvious trend of changing to a variable system. Because the variable system compensates by increasing the flow rate when the pressure decreases during the working process of the oil pump, the power of the hydraulic pump remains constant, that is, the hydraulic excavator equipped with the variable pump can regularly make full use of the maximum power of the oil pump.

When the external resistance increases, the flow is reduced (speed is reduced), so that the digging force is doubled; a three-circuit hydraulic system is used. Generates three independent work movements that do not affect each other. To achieve power matching with the slewing mechanism. Turning the third pump on on the other working motion becomes the second independent rapid motion of the open circuit. In addition, hydraulic technology is widely used in excavators, creating conditions for the application and promotion of electronic technology and automatic control technology in excavators.

7. Rapidly expand the application of electronic and automation technology in excavators. In the 1970s, in order to save energy consumption and reduce environmental pollution, make the operation of excavators light and safe, reduce the noise of excavators, and improve the working conditions of drivers, electronic and automatic control technology was gradually applied to excavation. With the improvement of performance requirements for excavators in terms of work efficiency, energy saving and environmental protection, easy operation, safety and comfort, reliability and durability, the application of electromechanical-hydraulic integration in excavators has been promoted, and its various performances have made a qualitative leap. .

In the 1980s, high-tech centered on microelectronics technology, especially the application of microcomputers, microprocessors, sensor&switch and detection instruments on excavators, promoted the application and promotion of electronic control technology on excavators, and has become an excavator. An important symbol of modernization, that is, the advanced excavation is equipped with electronic control systems such as engine automatic idle speed and throttle control system, power optimization system, working mode control system, and monitoring system.

8. Paying more attention to environmental protection, manufacturers such as CAT and Komatsu have launched excavators that meet the three emission requirements.