The single-pump and dual-pump systems of excavators differ significantly in structure, function, and application scenarios. The core difference lies in the fact that the dual-pump system provides multiple hydraulic oil outputs through two independent pump bodies, thereby supporting more complex compound actions and higher work efficiency, while the single-pump system has a simple structure and is usually used for small or low-load equipment.
Structural Differences:
A single-pump system contains only one hydraulic pump, is compact, and has a lower cost, making it suitable for small excavators. A dual-pump system consists of two pump bodies (such as gear pumps or piston pumps) connected by a coupling or flange. Common configurations include dual-pump single-circuit or dual-pump dual-circuit systems. Some models also include a pilot pump (such as a gear pump) in series to simplify layout.
Working principle
1. Single pump system: The flow rate is fixed, and the speed is adjusted by a throttle valve. All actuators (such as boom and bucket) share the same oil circuit. Insufficient oil pressure or delayed action may occur during combined operation.
2. Dual-Pump System:
Dual-Circuit Design: Two pumps drive different circuits (e.g., one pump controls the boom, the other controls the bucket), enabling independent operation of multiple actions without interference.
Power Distribution: The two pumps can operate in parallel or in series. In parallel operation, they utilize engine power to improve efficiency; in series operation, a through-shaft structure enables high-pressure output (rated pressure up to 34MPa).
Variable capacity: Modern dual pumps mostly use variable pumps, which automatically match the load by adjusting the swashplate angle to reduce power loss.
Performance Characteristics
1. Single-pump system: Advantages include simple structure and low maintenance cost, but low efficiency in compound actions, and it is only suitable for light-load or single-task scenarios.
2. Dual-Pump System:
Advantages: Supports simultaneous operation of multiple actuators (such as combined traveling and rotating movements), provides stable oil pressure and fast response; reduces hydraulic shock through dual-circuit design, extending component life.
Limitations: Complex structure, higher cost, and stricter requirements for hydraulic oil cleanliness.
