The Features of Engineering Machinery
Engineering machinery, also called construction machinery, is mainly used for the construction, renovation and maintenance of various types of electromechanical device. Widely distributed in industrial and civil construction, urban construction, national defense construction projects, transportation construction, mining and other raw material industry construction and production, agriculture, forestry and water conservancy construction, sanitation and environmental protection industries. It contains a wide variety of types, such as: excavators, loaders, cranes, pump trucks, pile drivers, hydraulic breakers, pavers, land levellers, jackdrills, etc.
Although the engineering machinery looks extremely complicated, the common features that can be summarized are:
1. Generally working outdoors
2. The work site often changes
3. The working environment is usually dusty or stainy.
Today's engineering machinery generally uses hydraulic transmission, because hydraulic transmission has the following obvious advantages compared with mechanical transmission:
1. The power-to-volume ratio is large, the position is easy to arrange.
2. Can achieve infinitely variable speeds
3. Easy to achieve overload protection
4. Less impact, vibration and noise
However, hydraulic transmissions have disadvantages compared to mechanical transmissions:
1. Easy to leak, not environmentally friendly
2. High manufacturing accuracy requirements
3. Less efficient
4. Uncertain gear ratio
Due to the special working environment of the engineering machinery, its hydraulic system has the following characteristics:
1. Working hours are irregular, sometimes working continuously for a long time.
2. The working environment is outdoors and dusty, the working temperature difference is large.
3. The machine itself travels, and the hydraulic tank is generally relatively small due to volume and weight limitations.
4. Due to volume and weight, the hydraulic system has a high working pressure, usually above 20 MPa, and high at around 40 MPa.
