Trials of the phase shift suspension tester
On September 26-29, 2022, at the Equipment Research Laboratory (ZDO), pilot tests of a device for controlling the condition of vehicle suspension based on the phase shift measurement method were conducted. The research was commissioned by the EGEA organization (European Garage Equipment Association), which is an international organization associating, among the others, manufacturers of equipment for vehicle inspection stations.
The aim of the tests was to verify the specification of equipment for vehicle suspension state control proposed by the EGEA organization using the phase shift method and the ability of the laboratory to test this type of equipment for compliance with the proposed specification.
The tests were attended by: Rafał Sosnowski (member of the EGEA board, president of STM), Jordi Brunet (secretary general of EGEA), Pavel Skuhravy (Modulatest s.r.o.), Massimo Xoccato (Snap-on), Christian Thalheimer (ASA Verband, MAHA Maschinenbau Haldenwang GmbH & Co. KG), Joan Lopez (AFIBA), Tomasz Rog (W.S.O.P. Sp.z o.o.), Aleksander Cwiszewski (UNIMETAL Sp.z o.o.).
Devices for controlling the condition of vehicles suspension measuring the phase shift are an extension of the devices based on the EUSAMA method, which measure the pressure on the plate during the forced, vertical movement of the plate of the device. The determined degree of adhesion is an indicator of the effectiveness of damping vibrations of the vehicle suspension. The method of phase shift, in simple terms, involves an additional analysis of the phase shift between the input (plate movement) and the response (wheel pressure on the plate) of the un-sprung mass of the vehicle falling on the tested wheel (figure below). Obtaining low values of phase shift indicates worn or damaged vehicle shock absorbers.
The open specification standard proposed by the EGEA organization and examined by the Motor Transport Institute (a unit that tests devices for compliance with the specification) may in the future result in the dissemination of the phase shift method.
