Out-of-center shaft alignment can occur due to non-compliance with machining tolerances or shaft bending. This is one of the factors that cause vibrations and heat in bearings. Therefore, measuring the degree of out-of-center alignment of critical sections of a rotor is one of the main steps in troubleshooting during the initial repair stages and quality control in the final repair stages. Although these measurements are traditionally performed using measuring gauges, systematic recording for issuing quality control certificates requires precision instruments to measure, record, process, and plot the relevant data.

Additionally, when using proximity sensors to measure the relative displacement vibration between the shaft and bearing, which is the most important protective and diagnostic signal for journal bearings, one source of error is the inhomogeneity of the magnetic properties of the shaft in the circular area opposite the sensor. API 610 has new recommendations for measuring journal bearing locations using proximity sensors. Therefore, another phase of quality control is measuring the level of this inhomogeneity, known as electrical (magnetic) out-of-center condition. For this purpose, measurements need to be taken using both mechanical methods (dial indicators or LVDT probes) and electrical methods (proximity probes), and their differences, which indicate the degree of magnetic out-of-center condition, should be calculated.

The ROD 401 measurement and display device for measuring the degree of shaft out-of-center alignment has been designed and manufactured for this purpose.