Marzocchi ALP2A-D-6-FG Hydraulic Gear Pump

1. Model Nomenclature Explanation

• ALP: Identifies the product series, representing Marzocchi’s standard pressure hydraulic gear pump series, which is distinct from the high-pressure GHP series and low-noise ELIKA series, and is mainly used for medium-pressure hydraulic system scenarios.
• 2A: Indicates the size group, belonging to Group 2 of the ALP series. This size group determines the pump’s basic installation dimensions, structural volume, and displacement range, making it suitable for medium-sized hydraulic systems that require higher flow output than Group 1 models.
• D: Specifies the installation method, referring to flange mounting. This mounting mode ensures firm connection with the hydraulic system, reduces vibration during operation, and simplifies disassembly, assembly, and maintenance processes.
• 6: Represents the displacement parameter, with a nominal displacement of 5.8 cm³/rev (cubic centimeters per revolution). This parameter directly determines the pump’s flow output capacity under a given rotational speed, which is a core indicator of the pump’s working efficiency.
• FG: Denotes the special configuration combination, where “F” stands for a built-in pressure relief valve—this valve automatically relieves pressure when the system pressure exceeds the rated value, effectively protecting the pump and the entire hydraulic system from overpressure damage; “G” indicates a standard mechanical seal, ensuring reliable sealing performance and preventing oil leakage in medium-pressure working conditions.

2. Core Technical Parameters

2.1 Displacement and Flow Rate

• Nominal Displacement: 5.8 cm³/rev (5.8 cc/rev), which is the core parameter determining the pump’s flow output capacity.
• Flow Rate at 1500 rpm: 8.7 L/min (liters per minute). Within the rated rotational speed range, the flow rate is positively proportional to the rotational speed; the actual flow output may have a slight deviation due to changes in system pressure, oil viscosity, and mechanical wear.

2.2 Pressure Ratings

• Maximum Continuous Operating Pressure: 250 bar (25 MPa). This is the maximum pressure that the pump can withstand during long-term continuous operation without causing damage to internal components such as gears and seals.
• Maximum Intermittent Pressure: 270 bar (27 MPa). This refers to the maximum pressure that the pump can bear for short periods (intermittent operation) during peak working conditions, such as sudden load increases.
• Peak Pressure: 290 bar (29 MPa). This is the maximum instantaneous pressure that the pump can withstand in emergency or short-term extreme working conditions; long-term operation at this pressure is strictly prohibited to avoid shortening the pump’s service life.
• Inlet Pressure: 0.7 – 3 bar (absolute pressure). Maintaining this inlet pressure range ensures stable oil suction, prevents cavitation damage to the gear pair and bearing, and ensures the pump’s normal operation.

2.3 Rotational Speed

• Minimum Operating Speed: 800 rpm. At this speed, the pump can ensure sufficient oil suction and stable hydraulic output, avoiding insufficient oil supply caused by low speed.
• Maximum Operating Speed: 5000 rpm. This is the upper limit of the rotational speed that the pump can bear; exceeding this speed will lead to excessive wear of internal components, increased noise, and reduced service life.
• Recommended Operating Speed Range: 1000 – 2000 rpm. Within this range, the pump achieves the optimal balance of volumetric efficiency, mechanical efficiency, noise, and service life, with a volumetric efficiency of up to 94%.

2.4 Working Medium and Environmental Conditions

• Recommended Working Medium: Hydraulic oil with a viscosity range of 6 – 500 cst; the optimal viscosity for startup and stable operation is 10 – 100 cst, which ensures good lubrication of internal components and smooth fluidity of the hydraulic oil.
• Operating Temperature Range: -10°C to +80°C. The pump can maintain stable performance within this temperature range, adapting to most industrial workshops and outdoor mobile working environments, without additional heating or cooling equipment under normal working conditions.
• Sealing Material: NBR (nitrile butadiene rubber) seals, which have excellent oil resistance, wear resistance, and sealing performance, effectively preventing hydraulic oil leakage and ensuring the integrity and stability of the hydraulic system.

3. Structural and Material Parameters

• Pump Body and Covers: Made of high-strength pressure-resistant aluminum alloy through die-casting. This material not only has excellent structural rigidity and corrosion resistance but also effectively reduces the overall weight of the pump, making it suitable for installation in medium-sized equipment with limited installation space.
• Gear Pair: Crafted from special hardened alloy steel, through precision grinding and heat treatment processes. This ensures high wear resistance, stable tooth meshing, low mechanical noise, effectively reduces energy loss during operation, and extends the service life of the gear pair to more than 8,000 working hours.
• Shaft Type: Conical shaft with a 1:8 taper and a 5 mm key (Type T1), with a shaft diameter of 15 mm, a shaft length (including fitting edge) of 40 mm, and a fitting edge diameter of 35 mm. The conical design ensures a tight connection with the drive device, preventing slippage during high-speed and high-torque operation.
• Flange and Ports: Equipped with a European standard 4-hole mounting flange, complying with SAE J 744 C standards, ensuring good compatibility with various hydraulic system installations. The inlet and outlet ports adopt BSPP threaded ports (3/4″ BSP thread), complying with SAE J 1926/1 (ISO 11926-1) standards, facilitating connection with hydraulic pipelines and reducing the risk of oil leakage.
• Shaft Load and Tightening Torque: Maximum shaft torque is 250 Nm, and the recommended shaft tightening torque is 80 ± 5 Nm. This torque range ensures a stable connection between the shaft and the drive device, avoiding damage to the shaft due to excessive or insufficient torque.

4. Performance Characteristics and Advantages

• High Efficiency: Within the recommended rotational speed range, the volumetric efficiency is up to 94%, and the overall efficiency is above 88%, which effectively reduces energy consumption and heat generation, lowering the long-term operating cost of the hydraulic system.
• Low Noise: The optimized gear tooth profile and strict manufacturing tolerances minimize fluid pulsation and mechanical vibration—two main sources of pump noise. Compared with ordinary gear pumps, its noise emission is reduced by 3-5 dB(A), improving operator comfort and reducing environmental noise pollution.
• Reliable Sealing: The standard mechanical seal (marked by “G” in the model) and NBR sealing materials form a double sealing protection, ensuring zero or minimal leakage even under maximum continuous operating pressure, maintaining the stability of the hydraulic system pressure.
• Built-in Protection: The integrated pressure relief valve (marked by “F” in the model) has a fast response speed, which can automatically release pressure when the system pressure exceeds the rated value, effectively protecting the pump, pipelines, valves, and other hydraulic components from overpressure damage, and improving the safety and service life of the entire hydraulic system.
• Easy Installation and Maintenance: The flange mounting design, standard interface specifications, and compact structure facilitate quick integration into various hydraulic systems. The simple internal structure makes daily inspection, maintenance, and component replacement convenient, reducing equipment downtime.

5. Application Scope

• Industrial Equipment: Medium-sized machine tools, hydraulic presses, plastic injection molding machines, hydraulic shearing machines, material handling equipment, and assembly line hydraulic systems, providing stable hydraulic power for precise movements and load-bearing operations.
• Mobile Equipment: Agricultural machinery (such as medium-sized tractors, harvesters, and agricultural irrigation equipment), small and medium-sized construction machinery (such as small excavators, loaders, and forklifts), and specialized mobile hydraulic equipment, adapting to the harsh working conditions of outdoor operations such as dust, vibration, and temperature changes.
• Other Fields: Hydraulic test benches, medium-pressure hydraulic control systems, light industrial automation equipment, and marine auxiliary hydraulic systems, where its high efficiency and reliability can meet the requirements of long-term stable operation.

6. Quality Assurance and Notes

• The pump must be operated within the rated pressure and rotational speed range, and overloading operation is strictly prohibited to avoid damage to internal components.
• Use hydraulic oil that meets the recommended viscosity requirements, and regularly replace the hydraulic oil and clean the oil filter to prevent impurities in the oil from wearing the gear pair, bearings, and seals.
• Regularly check the sealing performance of the pump. If oil leakage is found at the shaft end or flange connection, replace the seals or gaskets in a timely manner.
• During installation, ensure that the flange connection is tight and the shaft alignment is accurate (the coaxiality error should not exceed 0.1 mm), to avoid vibration and wear caused by misalignment.
• Before starting the pump, ensure that the hydraulic system is filled with hydraulic oil to avoid dry friction of internal components, which may cause severe wear.