Loaders are earth-moving machines widely used in highway, railway, construction, hydropower, port, mining, and other construction projects. They are primarily used for shoveling, loading, unloading, and handling soil, stone, and other bulk materials. They can also perform light excavation of rock and hard soil. By switching to a different attachment, they can also perform tasks such as bulldozing, lifting, loading, and unloading other materials. In highway construction, it is primarily used for filling and excavation in roadbed engineering, as well as for aggregate handling and loading operations at asphalt and cement concrete yards. Due to its fast working speed, good maneuverability, and ease of operation, it has developed rapidly and has become the primary machinery in earth and rock construction.

Classification of Loaders

Commonly used single-bucket loaders are classified based on engine power, transmission type, walking system configuration, and loading method.

1. Engine power:

A small loader with a power rating of less than 74 kW.

The power output of the medium-sized loader ranges from 74 to 147 kW.

The power output of the large loader ranges from 147 to 515 kW.

The power of the extra-large loader exceeds 515 kW.

2. Transmission form:

Hydraulic-mechanical transmission, low impact and vibration, long service life of transmission components, convenient operation, and automatic adjustment of vehicle speed and external load capacity; generally used in medium- and large-sized loaders;

Hydraulic Transmission: Stepless speed control, convenient control room, but poor stability; generally used only on small loaders;

Electric drive: Stepless speed control, reliable operation, simple maintenance, high cost; generally used on large loaders.

3. Walking structure:

Tire type: lightweight, fast, highly maneuverable, highly efficient, causes minimal damage to the road surface, high ground contact pressure, poor passability, yet it is widely used;

Crawler type: Low ground contact pressure, good passability, low center of gravity, good stability, strong adhesion, high traction, high specific cutting force, low speed, relatively poor flexibility, high cost, and a tendency to damage the road surface when in use.

4. Loading and unloading methods:

Front-loading type: Simple structure, reliable performance, clear visibility, suitable for various work sites, and wide range of applications;

Rotary type: The working device is mounted on a turntable capable of rotating 360O, and side unloading does not require turning the unit around. While it offers high operational efficiency, its structure is complex, it is heavy, it is expensive, and it has poor lateral stability. It is suitable for smaller venues.

Rear unloading type: front loading, rear unloading, high work efficiency, poor work safety.

Principles for Selecting Loaders

Model selection: The selection and determination are primarily based on the operating conditions and purpose. Generally, crawler loaders are used for operations in quarries and on soft ground;

Power selection: Generally, diesel engines are commonly used in construction machinery. For operations in special areas, such as locations at altitudes higher than 3,000 meters, specialized engines should be used. High-altitude diesel engine;

Selection of transmission type: Generally, a hydraulic-mechanical transmission is used. The key factor is the choice of torque converter type. Currently, most loaders manufactured in my country use dual-turbine, single-stage, two-phase torque converters.

When selecting a loader, its braking performance must be fully considered, including multiple brakes, parking brakes, and emergency brakes. There are three types of brakes: shoe-type, caliper-disc-type, and wet multi-disc-type. The brake actuation mechanism typically uses a servo-assisted system, and its power sources come in three types: compressed air, air-oil, and hydraulic. Currently, the air-oil braking system is commonly used, and a dual-circuit braking system is generally employed to enhance driving safety.