Explanation of radial force in Voith gear pumps

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When a Voith gear pump is in operation, the radial forces acting on its bearings consist of the radial force generated by the liquid pressure along the circumference of the gears, as well as the radial force resulting from the meshing of the gears. This phenomenon is collectively referred to as the radial force problem of Voith gear pumps. 　　When a gear pump is in operation, within the radial clearance between the gears and the inner hole of the casing, the liquid pressure distribution from the suction chamber to the discharge chamber increases gradually in stages; this represents the approximate curve of the liquid pressure. The magnitude of the radial force FP generated by the liquid pressure on the driving gear and the driven gear is exactly the same, and its direction is vertically downward toward the oil suction chamber. The magnitude of the radial force FT generated by gear meshing on the driving gear and the driven gear is approximately equal, but their directions are different. Therefore, the resultant radial force acting on the driving gear can be obtained by adding the radial force generated by the liquid pressure around the gear’s circumference to the radial force resulting from gear meshing. Clearly, the resultant force on the driven gear is greater than that on the driving gear. Therefore, when the bearing specifications on the driving wheel and the driven wheel are the same, the bearings on the driven wheel wear out more quickly. To make the lifespans of the two bearings equal or similar, the oil pressure port can be shifted to the side with less radial force, thereby making the resultant force on the pinion greater than that on the driving gear. 　　Since the aforementioned radial force is an unbalanced force, and the higher the operating pressure, the greater the radial unbalanced force. In severe cases, it can cause the gear shaft to deform, the oil intake side of the housing to be scratched by the gear teeth, and at the same time accelerate bearing wear, thereby reducing the pump’s lifespan. 　　Hydraulic equipment maintenance site at the port. One of the common methods to reduce radial unbalance forces is to choose the gear module and tooth width B appropriately: for low-pressure gear pumps, a certain value is used; for medium- and high-pressure gear pumps, another value can be adopted, which helps to reduce radial forces without decreasing volumetric efficiency. The second method is to change the pressure distribution pattern along the circumferential direction; for example, by reducing the size of the oil inlet of the pump so that the pressurized oil acts only over a range of one tooth to two teeth, or by creating oil grooves (balancing grooves) on the cover plate or the outer periphery of the shaft sleeve in order to reduce radial forces. The balance grooves 1 and 2 provided on the cover are connected to the low-pressure chamber and the high-pressure chamber respectively, thereby generating a hydraulic radial force that counteracts the forces in the oil suction chamber and the oil compression chamber, thus balancing these radial forces. 　　Address the radial force issue associated with the Voith gear pump, adjust the effect of this radial force, control and reduce any imbalances in radial force, thereby maintaining the stability of the hydraulic pump as well as its volumetric efficiency.