Mini Excavators: 

① Definition and Core Functions: A mini excavator refers to excavation equipment with a total weight not exceeding 6 tons and a bucket capacity ranging from 0.05 to 0.3 cubic meters, capable of performing multiple functions such as excavation, crushing, and loading. It is suitable for construction in confined spaces, such as urban municipal maintenance, rural homestead construction, and indoor demolition. In urban village renovation projects, micro excavators can maneuver flexibly through alleys as narrow as 1.5 meters to complete underground utility trenching. During rural self-built housing construction, they can precisely excavate foundation trenches with a depth tolerance of ±5 centimeters. Standards require 8 hours of continuous operation without failure, with a digging force of no less than 80% of the machine’s total weight, ensuring stable and efficient performance in various light-duty applications.

② Selection of Core Components and Materials: Core components include the hydraulic system, travel system, excavator arm, and bucket. The hydraulic system employs a high-pressure gear pump with an operating pressure of 20 MPa to 25 MPa. The hydraulic hoses are made of high-pressure-resistant rubber, maintaining good flexibility in temperatures ranging from -30°C to 80°C to prevent brittle fracture at low temperatures or aging at high temperatures. The travel system is typically track-type, with track plates made of high-manganese steel with a hardness of HRC 50 or higher, reducing wear rates by 40% when operating on gravel surfaces; Some small micro-excavators are equipped with rubber tracks, suitable for indoor tile flooring construction to prevent surface scratches. The excavator arm is fabricated from Q355 steel plates with a thickness of 8 mm to 12 mm; welded joints undergo non-destructive testing to ensure the absence of porosity or cracks. The bucket teeth are made of alloy steel, offering a service life three times longer than ordinary steel and resisting chipping when excavating hard soil.

③ Working Principle and Operation: During operation, the engine drives the hydraulic pump to generate high-pressure oil, which is then delivered through hydraulic lines to various hydraulic cylinders. The control levers operate the hydraulic valves to adjust the extension/retraction speed and force of the cylinders, enabling actions such as raising/lowering the excavator arm and tilting the bucket. For example, during excavation, pushing the boom lower lever causes the boom cylinder to retract, lowering the boom to the ground. Next, operating the dipper lever extends the dipper cylinder, driving the bucket into the soil. Finally, operating the bucket lever retracts the bucket cylinder, completing the soil excavation. The operating modes are divided into pilot control and mechanical control. Pilot control is managed via hydraulic pilot valves, requiring minimal operating force and offering high precision, making it suitable for delicate tasks such as digging tree pits during municipal landscaping. Mechanical control is managed via control rods, featuring a simple structure and low maintenance costs, and is commonly used in simple rural construction scenarios. The equipment is equipped with a rotating cab that can rotate 360 degrees, allowing the operator to observe the work area and reduce blind spots.