Detailed information on Rexroth gear pump AZPU series — shared by Autos

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Features of the Rexroth AZPU series gear pumps: – Nominal pressure of 280 bar – Use of sliding bearings, making them suitable for heavy-duty applications – Drive shafts that meet ISO or SAE standards – Possibility of combining multiple pumps together – Pipe connections: flange-type fittings – Optimized pressure pulsations, thereby reducing noise emissions and vibration in the system – Extended service life thanks to the reinforced design of the shafts and the material used for the pump cover – Consistent high quality achieved through mass production – Various configuration options available. Overview of the Rexroth AZPU series gear pumps: An important function of external gear pumps is to convert mechanical energy (torque and speed) into hydraulic energy (flow rate and pressure)； External gear motors are the exact opposite. These devices must have high efficiency to avoid generating unnecessary heat. This high efficiency is achieved through precise manufacturing processes and pressure-sensitive gap sealing. Furthermore, in this low-noise silent pump, this double-flange principle helps to reduce flow pulsation by up to 75%. Displacement method for Rexroth AZPU series gear pumps: The sealed area of the displacement gear pair, in combination with the rotation mode of the drive shaft, results in the flow characteristic curve shown in the left diagram (schematic). In a standard hydraulic pump, each time a pair of gears meshes, there is a pulsation on this characteristic curve. After adopting the double-flange structure, the flow pulsation of this silent pump was reduced by 75% – which in turn reduced the flow pulsation on the components of the downstream system – with the new frequency being equal to twice the fundamental frequency. During this process, the gear pair exhibits a smaller backlash on the rear tooth surface; as a result, hydraulic sealing is provided not only by the front tooth surface of the driven gear but also by its rear tooth surface. In this way, liquid flow is discharged alternately from the front and rear tooth surfaces. Moreover, by adjusting the shape of the metering orifice, the hydraulic action line can be expanded to half that of a standard hydraulic pump. Structure of the Rexroth AZPU series gear pump: This external gear pump consists mainly of a pair of gears supported on bearing bushes or bearings (depending on the specific series), as well as a pump casing equipped with a front cover and a rear cover. The drive shaft extends outward from the front cover of the pump and is sealed by a shaft seal. These supporting forces on the bearings are absorbed by specialized sliding bearings ； Due to the sufficient elastic force of the sliding bearing, a surface contact is formed rather than a line contact. As a result, this also ensures excellent wear resistance of the pump—especially when operating at low speeds. These gears each have 12 teeth, which helps to maintain minimal flow pulsation and noise in the gear pump. Internal sealing is achieved through compensating forces, which are proportional to the output pressure. By using this compensation method, optimal efficiency can be ensured. By applying working pressure to the rear part of the bearing bush, the sealing area between the gear teeth and the bearing can be controlled. These specialized seals form the boundary of this area. As for these radial gaps at the top of the gear teeth, sealing is achieved through the force that pushes the gear inward toward the pump casing. Specifications of Rexroth AZPU series gear pumps: Structure: External meshing gear pump. Installation: Flange or through-bolt with sleeve. Oil inlet: Flange. Rotation direction (viewed from the shaft): Clockwise or counterclockwise; the hydraulic pump can only be driven in the direction indicated in the diagram. Installation location: Any location. Load on the shaft: Radial and axial forces, to be determined upon consultation. Ambient temperature range: –30°C...+80°C, with NBR seals; –20°C...+110°C, with FKM seals. Hydraulic oil: Mineral oil that meets DIN 51 524, grades 1-3 ； However, under higher load conditions, an HLP hydraulic fluid that meets the recommendations should be used at least ； – Meets RC 90220 requirements ； – Upon consultation, other viscosities for working fluids can be used: 12...800 mm2/s, with an allowable range of 20...100 mm2/s and a recommended range of ...2000 mm2/s. The temperature range allowed for starting the pump is: –30°C...+80°C or –20°C...+110°C. FKM seals are used for filtration; the cleanliness level should be at least 20/18/15, in accordance with ISO 4406 (1999). Precautions for Rexroth AZPU series gear pumps: Most failures of external gear pumps are caused by contaminated hydraulic oil. Given that the warranty terms do not cover wear caused by contamination, it is recommended to use filtration methods that meet the ISO 4406 cleanliness levels of 20/18/15, in order to reduce contamination in terms of particle size and concentration to acceptable levels: operating pressure >160