In the power transmission system of the loader, the torque converter, as a key component connecting the engine and the gearbox, plays an important role in flexible power transmission and load adaptation and adjustment. The working pump, steering pump and speed pump installed around the torque converter are called the "three core hydraulic pumps". They provide hydraulic power for the loader's operating device, steering system and gearbox shifting, respectively, and are the "power center" to ensure the efficient and safe operation of the equipment.
1. Working pump: the "power engine" that drives the operating device
The working pump is usually directly connected to the output end of the torque converter through gear transmission or transmission shaft, and is mostly installed at the front end or side of the torque converter housing. It is the hydraulic pump with the largest flow and the highest load among the three pumps. Its power comes directly from the mechanical energy transmitted by the engine through the torque converter. Through the speed increase or deceleration characteristics of the torque converter, the output power can be automatically adjusted according to the operating load.
2. Steering pump: the "control core" to ensure driving safety
The steering pump is mostly arranged in parallel with the working pump at the front end of the torque converter, and is linked through the same drive shaft or gear set. Some models adopt an integrated pump set design, which shares the housing with the working pump but has an independent oil circuit. Its installation position is close to the front end of the engine, away from the high temperature area of the torque converter, to reduce the impact of oil temperature on the performance of the hydraulic oil.
3. Speed change pump: the "shift center" for regulating the gearbox shift
The speed change pump is embedded in the connection between the torque converter and the gearbox, usually installed inside the torque converter housing, and driven by the torque converter turbine shaft or a dedicated drive gear. Its working environment temperature is relatively high (affected by the hot oil radiation of the torque converter, the ambient temperature can reach 80-120℃), so it has strict requirements on sealing performance and high temperature resistance.
Although the three pumps have independent functions, they form an organic linkage through the torque converter: when the engine power is transmitted through the torque converter, the three pumps are driven to operate synchronously, and the hydraulic oil is transported to the target system through their respective oil circuits, and the excess oil returns to the oil tank through the return oil pipeline for cooling and filtration. When the working pump increases its flow rate due to heavy-load operation requirements, the torque converter will automatically distribute power through the hydraulic coupling characteristics to ensure that the basic pressure of the steering pump and the speed change pump is not affected; when steering or shifting, the priority valve of the corresponding system will prioritize the oil circuit pressure to form a "dynamically balanced" hydraulic network.
