The hydraulic pump is the core component of the hydraulic system.They can convert mechanical energy into hydraulic energy. Different types of pumps are suitable for different application scenarios. Hydraulic piston pumps and hydraulic gear pumps are the two most common types. You can select the appropriate hydraulic pump for your hydraulic system from the comparison guide on this page.
What is the Hydraulic Piston Pump and the Hydraulic Gear Pump?
The hydraulic piston pump uses the reciprocating motion of the hydraulic cylinder to achieve the suction and discharge of oil. They are high pressure,high accuracy flow with capacity adjustable and moderate operating sound. But they have a complex structure and high consumption, and still the cleanliness requirement for oil is quite high. This is in the form of an axial piston and radial piston pump. And universal use of the axial piston pump has resulted.
Hydraulic gear pumps are driven Hydraulic gear pumps perform oil suction and discharge as the gears revolve in meshing with each other. Simple in construction, inexpensive and highly resistant to contamination; well suited for low pressure applications. Nevertheless, they present poor flow accuracy and relatively high operation noise. They fall into two types – the externally gear pump which we are most familiar with and the internally gear pump.
Detailed Performance Comparison
Pressure Range Comparison
In terms of pressure performance, hydraulic piston pumps demonstrate significant advantages. Relying on the precise fit between the plunger and cylinder block, coupled with a high-strength structural design, they can reliably withstand high pressures. Their rated working pressure is generally ≥20MPa, with some high-pressure models capable of reaching hundreds of MPa. So, it is suitable for high-pressure systems such as hydraulic presses and heavy-duty construction machinery.
Conversely, hydraulic gear pumps are constrained by gear meshing clearance sealing performance and pump body strength, making them suitable only for low-pressure applications. Their rated working pressure is typically ≤16MPa, with few medium-pressure models exceeding 20MPa. Under high pressure, leakage can cause efficiency to plummet and components to fail.
Comparison of Flow Accuracy and Adjustment
The gap between the piston and the cylinder body of the hydraulic piston pump is very small, and the volumetric efficiency can reach 85% – 95%. It can stably output the flow rate and precisely match the stable flow demand of the hydraulic power system. And you can adjust the tilt angle of the diaphragm to precisely regulate the output flow rate and adapt to the flow demand of different working conditions of the system.
The pitch error and tooth clearance variation during gear meshing in hydraulic gear pumps cause significant pulsation in the output flow. This makes them incapable of providing precise power to equipment requiring high flow stability. Furthermore, the flow rate of hydraulic gear pumps is solely determined by gear parameters and rotational speed, lacking any self-regulating capability to alter output flow. Adjusting flow can only be achieved by changing the motor speed, resulting in significantly lower flexibility compared to variable displacement piston pumps.
Efficiency Comparison
The hydraulic piston pump has a higher mechanical efficiency. The friction coefficient of the plunger in the cylinder body is low, resulting in low mechanical loss. This makes the overall efficiency usually 10% – 15% higher than that of gear pumps. Over the long term, it can effectively reduce energy loss and lower the operating cost of the equipment.
Hydraulic gear pumps experience significant sliding friction losses at gear meshing points, and oil leakage often occurs at gear clearances and end cover seals. Consequently, their volumetric efficiency is relatively low, mechanical efficiency is comparatively loose, and overall efficiency suffers a 10% to 15% loss compared to plunger pumps. In applications requiring long-term continuous operation, this lower efficiency increases motor energy consumption, translating to additional operating costs over the cycle.
Comparison of Hydraulic Oil Requirements
Hydraulic piston pumps impose stringent requirements on hydraulic oil.The mating surfaces between the hydraulic piston, the distribution plate and the cylinder body are very precise. They are highly susceptible to being scratched or jammed by solid particles in the oil. This leads to a decline in sealing performance, an increase in leakage, and even component damage. Therefore, when using, a high-precision oil filter must be used in conjunction, and the hydraulic oil needs to be replaced regularly, which increases the complexity and cost of system maintenance.
Hydraulic gear pumps have relatively lenient requirements for hydraulic fluid. Due to their simple structure and use of clearance sealing characteristics, these pumps can tolerate a certain degree of fluid contamination. They also accommodate a wide range of viscosities. You need not perform frequent fine filtration of the fluid; meeting operational requirements is achievable through regular fluid changes and ensuring the fluid has not undergone severe degradation.
Noise Comparison
Hydraulic piston pumps operate at relatively low noise levels. Their working principle relies on the smooth reciprocating motion of the piston within the cylinder to draw in and expel fluid. This process involves no violent impacts or gear friction. Certain high-pressure models can further reduce noise through structural optimization and the addition of muffling devices. Operating noise is typically controlled within the 65-75 dB range. You can select this pump for use in noise-sensitive equipment or indoor environments.
The operating noise generated by hydraulic gear pumps is relatively large. This is mainly due to the mechanical shock during the gear meshing process, the cavitation phenomenon caused by the volume changes in the gear grooves, the oil leakage and turbulence caused by the clearance sealing, and other factors. Although the noise can be reduced by adjusting the gear tooth profile and optimizing the pump body structure, the basic operating principle of these pumps determines that the noise level is usually between 75 and 85 decibels. They are more commonly used in low-pressure general equipment with less stringent noise requirements, such as small machine tools and agricultural machinery.
Durability Comparison
The durability of a hydraulic piston pump depends on operating conditions and maintenance. Its core components need to be precisely aligned. Impurities in the oil can cause component wear and seal failure, directly shortening the service life. Although the structure is robust under high-pressure conditions, complex moving parts such as the swashplate and piston are prone to fatigue damage during long-term heavy-load operation. If you do not perform proper maintenance – such as insufficient lubrication or incorrect assembly – the durability will be significantly reduced. Strictly controlling the cleanliness of the oil and conducting regular professional maintenance are the key to ensuring the long-term stable operation of the equipment.
The hydraulic gear pump demonstrates greater applicability under normal operating conditions. It has a simple structure and fewer components. The core components such as gears and pump bodies are usually made of high-strength metals, thus possessing excellent shock resistance and wear resistance. Moreover, this pump has relatively loose requirements for the cleanliness of the oil, and is less likely to be blocked or damaged by trace impurities. Under low-pressure conditions and with regular maintenance cycles, its service life is longer and the failure rate is lower.
Cost and Maintenance
Hydraulic piston pumps are usually expensive. They are complicated to make and have many precision parts. And it makes them more expensive to manufacture and purchase than the gear pump. Moreover, their maintenance costs are high, requiring professional tools and skilled operators for maintenance. Because of the strict demand of hydraulic oil cleanliness, they should be installed with a high efficiency filter and have regular oil condition checks. If you need to replace precision components during maintenance, the cost will also be very high.
The cost of hydraulic gear pumps is relatively low. They have a simple structure, fewer components and a straightforward production process. Its manufacturing and selling prices are much less than hydraulic piston pumps. It is easy to maintain hydraulic gear pumps. No professional skills are required; only regular checks of the oil and occasional replacement of ordinary filters are needed. The components that are prone to failure in hydraulic gear pumps are usually gears and seals, but the replacement cost is relatively low. Maintenance personnel can be competent after a short training, which significantly reduces the overall maintenance cost.
Applications
Hydraulic Piston Pumps
High-pressure and high-precision equipment: such as precision CNC machines, large hydraulic excavators, injection molding machines, etc.
Priority scenarios for performance: such as aerospace hydraulic systems, hydraulic presses, high-end mining machinery.
Hydraulic Gear Pumps
Low-pressure basic power scenarios: such as agricultural machinery, small hydraulic tools, machine tool lubrication systems.
Cost-sensitive and simple working conditions: such as small loaders, hydraulic baling machines, auxiliary oil circuits of construction machinery.
Recommendations for Selection
If you need to use the hydraulic pump for a long time under high pressure (usually greater than 16 megapascals) and high flow rate conditions,and have strict requirements for the accuracy of pressure and flow regulation as well as the stability of the system. At the same time, your budget can afford higher maintenance costs, then you can choose the hydraulic piston pump. This pump can provide precise power output under heavy load conditions.
If you need to use a hydraulic pump at low pressure (usually ≤ 16 MPa) and with medium to small flow rates. And you need to control costs while emphasizing ease of maintenance. You can choose a gear pump. It does not require complex pressure regulation and has low requirements for the contamination of hydraulic oil. Its low cost, resistance to contamination, and ease of maintenance make it more suitable for such applications.
Conclusion
Different hydraulic pumps have different functions. Choosing the appropriate hydraulic pump is of great significance. We hope you can select the hydraulic pump that suits you from the introduction and comparison on this page.
