The present invention relates to a method for determining a present state of wear of a hydrostatic machine during the operation of the hydrostatic machine. The hydrostatic machine comprises a drive with variable rotational speed and a hydrostatic pump, wherein the drive is designed to drive the hydrostatic pump for generating a volume flow of a fluid, and wherein the hydrostatic machine is connected to a fluid transport channel in which the fluid is transported in a manner driven by the hydrostatic machine. The method has a step for determining a first torque of the drive at a specified drive vector. Furthermore, the method has a step for ascertaining a second torque of the drive at the specified drive vector using a first calculation method, and in addition, the method has a step for determining the present state of wear of the hydrostatic machine using a second calculation method, in order to compare the first determined torque and the second ascertained torque to one another.

A system including a cartridge and an actuating device for actuating the cartridge, wherein the actuating device includes a housing having an interior space in which a linearly acting drive is arranged, the cartridge includes a cylinder space and a displacement element movably arranged in the cylinder space, wherein the displacement element subdivides the cylinder space into a containing space for receiving the viscous medium and an empty space and separates them from each other in a fluid-tight manner, wherein the linearly acting drive can be engaged with the displacement element of the cartridge, wherein the cartridge and the housing each include connecting elements for releasable connection to each other along a joining direction, wherein a seal acting axially with respect to the joining direction is arranged between the housing and the cartridge, and wherein the interior space and empty space are sealed in an airtight manner in the connected state.

A wellbore servicing method comprising transporting a pump unit comprising a unit controller and pumping equipment to a wellsite. Executing a design process on the unit controller to determine a concentration of a wellbore treatment fluid at a wiper plug within an oilfield tubular. The design process utilizes a CFD model to generate a static mesh representative of the geometry of the oilfield tubular, locate the wiper plug within the static mesh, and determine a fluid velocity on each side of the wiper plug with flexible static mesh cells. The CFD model can generate a prediction of the concentration of the wellbore treatment fluids in response to the wiper plug reaching a target location within the oilfield tubular.