A loader is a widely used earthmoving machine in construction projects such as highways, railways, buildings, hydropower, ports, and mines. It is primarily used for loading and unloading bulk materials such as soil, sand, gravel, lime, and coal, and can also perform light digging operations on ores and hard soil. With different auxiliary working devices, it can also perform bulldozing, lifting, and loading/unloading operations on other materials such as timber. So, what are the working principles of a loader's gearbox?
Working Principle of a Loader Gearbox: A hydraulic torque converter is a non-rigid torque converter that uses liquid as the working medium and is one form of hydraulic transmission. The diagram shows a hydraulic torque converter, which has a closed working chamber where liquid circulates. The pump impeller, turbine, and guide wheel are connected to the input shaft, output shaft, and housing, respectively. When the power unit (internal combustion engine, electric motor, etc.) drives the input shaft to rotate, the liquid flows out from the centrifugal pump impeller, passes sequentially through the turbine and guide wheel, and returns to the pump impeller, circulating continuously. The pump impeller transfers the mechanical energy of the input shaft to the liquid. The high-speed liquid drives the turbine to rotate, transferring energy to the output shaft.
A hydraulic torque converter transmits torque by generating a change in angular momentum through the interaction between the fluid and the blades. A key difference between a hydraulic torque converter and a hydraulic coupling is its fixed guide wheel. The guide wheel's flow-guiding effect on the fluid allows the output torque of the hydraulic torque converter to be higher or lower than the input torque, hence the name "torque converter." The ratio of output torque to input torque is called the torque converter coefficient, which is typically around 2–6 at zero output speed. The torque converter coefficient decreases as the output speed increases. The input and output shafts of a hydraulic torque converter are connected by fluid; there is no rigid connection between the working components. The characteristics of a hydraulic torque converter are: it can eliminate shock and vibration; it has good overload protection and starting performance; the output shaft speed can be higher or lower than the input shaft speed, and the speed difference between the two shafts varies with the magnitude of the transmitted torque; it has good automatic speed change performance, automatically decreasing the output speed when the load increases and automatically increasing it when the load decreases; it ensures a stable operating range for the power unit, and transient changes in load are largely not reflected in the power unit.
