What is the working principle of a Rexroth gear pump?

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Many customers, or rather not just customers, but also some smaller suppliers, only know about Rexroth gear pumps without understanding how they work. Unlike Rexroth piston pumps, Rexroth gear pumps differ from them in fundamental ways. Today, Autos will explain to you how Rexroth gear pumps work. In fact, the concept of a Rexroth gear pump is quite simple: its most basic form consists of two gears of the same size that mesh with each other as they rotate inside a tightly fitting housing. The interior of this housing has an “8” shape, and the two gears are located within it, with their outer diameters and sides fitting tightly against the housing. The material coming from the extruder enters between the two gears at the inlet and fills this space; as the gears rotate, it moves along the housing, and is finally discharged when the two gears mesh. In terms of terminology, a gear pump is also known as a positive-displacement device; it functions like a piston inside a cylinder, and as one tooth enters the fluid space occupied by another tooth, the liquid is mechanically forced out. Since liquids are incompressible, the liquid and the tooth cannot occupy the same space at the same time; as a result, the liquid is displaced. Due to the continuous meshing of the teeth, this phenomenon occurs continuously, thereby providing a steady discharge volume at the pump’s outlet; the amount discharged is the same with each rotation of the pump. As the drive shaft rotates continuously, the pump also continuously dispenses fluid. The flow rate of the pump is directly related to its rotational speed. There is a small amount of fluid loss inside the pump, which prevents the pump’s operational efficiency from reaching 100%; this fluid is used to lubricate the bearings and the gears. Moreover, it is impossible for the pump components to fit together without any gaps, so it is not possible to allow 100% of the fluid to be discharged from the outlet. Therefore, some amount of fluid loss is inevitable. However, the pump can still operate well, achieving an efficiency of 93% to 98% for most extruded materials. For fluids whose viscosity or density varies during the process, this pump is not greatly affected. If there is a damper, such as a filter or a restrictor placed on the outlet side, the pump will push the fluid through them. If this damper changes during operation, that is, if the filter becomes dirty or clogged, or if the back pressure of the regulator increases, the pump will still maintain a constant flow rate until it reaches the mechanical limit of the weakest component in the system (usually a torque limiter is installed). The speed of a pump is actually limited, and this limitation mainly depends on the process fluid. If oil is being transported, the pump can rotate at high speeds, but when the fluid is a highly viscous polymer melt, this limitation is significantly reduced. It is very important to push the high-viscosity fluid into the two-tooth space on the suction side; if this space is not filled completely, the pump will not be able to deliver a precise flow rate. Therefore, the PV value (pressure × flow rate) is another limiting factor, and it is also a process variable. Due to these limitations, gear pump manufacturers will offer a range of products, namely different specifications and displacements (the volume discharged per revolution). These pumps will be matched to specific application processes to optimize system performance and cost. That’s the working principle of Rexroth gear pumps. As a professional distributor of Rexroth gear pumps, including companies like Autos that handle the repair of hydraulic pumps, it’s essential to master these principles. If one doesn’t even understand them, how can they introduce products to others? The original text is from http://www.kelanpump.com/news.php?nid=21