Hydraulic pump is the core power source of hydraulic system of small excavator, which directly determines the working efficiency, oil consumption, control feel and service life of equipment. At present, the mainstream of small excavators in the market is equipped with two kinds of hydraulic pumps: gear pump and piston pump. Their core principles, performance parameters and applicable scenarios are very different, which is also the key difference between high and low equipment. It is difficult for many machine friends to distinguish between type selection and maintenance. Today, the core differences between the two are dismantled in detail to help accurate type selection and maintenance.
From the structural principle, the gear pump has a very simple structure, which relies on the meshing and rotation of gears to transport hydraulic oil. It belongs to a quantitative pump, and its output flow is fixed and cannot be adjusted, with few integral parts and extremely low failure rate. The plunger pump relies on the reciprocating motion of the plunger to complete the oil supply, and most of them are variable pumps, which can automatically adjust the flow and pressure according to the excavation load and working speed. The structure is precise and complex, and the integration is higher. It is the core configuration of the high-pressure hydraulic system.
The gap between performance and working conditions is the most obvious. The gear pump belongs to the medium and low pressure pump, and its normal working pressure is 160-250bar, with limited upper pressure limit. Under the high pressure condition, the problems of internal leakage and rising oil temperature are easy to occur. During operation, the flow pulsation is large, the noise is high, and the smoothness of compound action is average. The plunger pump is specially equipped with high pressure, and its working pressure can reach 280-420bar. It has stable pressure, small flow pulsation, precise and delicate control, powerful heavy-load excavation, excellent micro-operation and composite operation, and is suitable for complex working conditions.
In terms of energy consumption and service life, the overall efficiency of gear pump is 80%-85%, and the excess flow needs to overflow and relieve pressure during heavy-duty operation, which leads to high energy consumption and high oil consumption, but it has strong oil pollution resistance and impact resistance, hard leather and low maintenance cost. The comprehensive efficiency of piston pump can reach 90%-93%, and the load adaptive speed regulation greatly reduces useless energy consumption, saves fuel and generates less heat, and has stronger long-term operation stability; The disadvantages are that the cleanliness of hydraulic oil is high, it is easy to be damaged due to improper maintenance, and the procurement and maintenance costs are higher.
In practical application, low-equipped micro-excavators, light agricultural and municipal small excavators are mostly equipped with gear pumps, which meet the requirements of mild leveling and digging operations and have outstanding cost performance. Piston pumps are widely used in new small excavators of over 6 tons and engineering models with high frequency operation, which are suitable for heavy load, high frequency and fine construction scenes.To sum up, the gear pump has the advantages of economy, durability, simple maintenance and adaptability to light load conditions; Piston pump wins in high efficiency, energy saving, strong performance and high standard operation. Machine friends can choose reasonably according to their own operation scenarios and budgets, taking into account the use cost and operation efficiency.
