Structural form of boom arm

The boom and arm refer to a working device of an excavator, usually also known as the upper arm or lower arm, which is mainly used to control the excavation, loading and other actions of the excavator bucket. The arm connected to the rack is relatively long, so it is commonly known as the boom, and its terminology is called the boom; The arms connected to the digging bucket are relatively small, so they are commonly known as small arms, and the terminology is called bucket rods, so they are commonly referred to as large and small arms.
The boom and arm are not solid, but adopt a box structure, that is, the cross-section is a rectangle welded from four steel plates, with nothing in the middle. Steel is the most suitable material for excavator boom in terms of strength, stiffness, fatigue performance, processability, and economy. The cross-sectional height of the boom and arm should not be too large, and the torsional performance should also be ensured. The box structure is equivalent to two parallel I-beams in terms of bending performance, and the torsional performance is better than the sum of two separate I-beams.