Knoll Maschinenbau GmbG

Why KNOLL Uses Universal Joints for the MX-Pump


Progressing cavity pumps are unmatched in their ability to transport viscous, abrasive and shear sensitive fluids. One of their important components is the joint, responsible for power transmission from the drive shaft to the rotor. Technically seen different solutions are possible here, for example the pin joint or a flexible rod.

KNOLL Maschinenbau has decided to use universal joints for the MX-Pump. These joints are characterized by robustness which is important in metering: An intermitting service for exact metering applies heavy loadings on the joint. Therefor KNOLL relies on the same quality standards as used in the autmotive industry for its universal joints. As a consequence the robustness of the joint is not only helpful in metering but also in transporting highly viscous media or working under high pressure.

But robustness is not the only important factor for the joint of a progressing cavity pump: As much as the joint should be robust as much it has to support the flow of any given media. The MX-Pump from KNOLL offers the same flow rate over the entire length of the suction housing due to the fact that the universal joint has the same diameter from front to end.

A third factor is hygiene: A pumps joint must support sanitary matters under many different circumstances. Depending on the media very high hygiene requirements have to be met. The universal joint of the MX is therefore provided with a specific hygiene sleeve so that no direct contact between transport media and the joint itself is possible. In addition the joint is life time lubricated. The lubrication with vegetable fat is designed for the life time of each MX-Pump. On the exterior, towards the transport media, the hygiene sleeve supports fast and easy cleaning with its dead end free construction. The photos in this article show the universal joint of the MX-Pump without (top) and with (bottom) sleeve.

By using a universal joint in KNOLL’s progressing cavity pump the joint itself no longer counts among the wear parts. In any case of failure very short downtimes are guaranteed, as the MX can quickly and easily be disassembled and reassembled. Therefore the MX from KNOLL Maschinenbau without doubt is a good choice not only due to its technical factors but also following the idea of total cost of ownership (TCO).