A problem with hydraulic installation is sometimes difficult to get clear. All mechanical parts have already been checked or replaced and the customer still complains about a spongy installation.
One of the options is then to monitor the oil condition over a longer period of time and analyse the data to see if there is air in the oil, for example, caused by the various hydraulic consumers.
This image shows the data measured over a period of 6 weeks. The oil condition (green) and oil temperature (orange). A trend line has been drawn over the oil condition. The oil condition has remained stable and the values do not indicate air in the oil.