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Mechanical and Climatic Calibration and Testing Laboratory


B. Tests to determine the damping characteristics of hydraulic and friction dampers

Reference documents:

  • NTF 67-003:2008 – Railway vehicles. 5,100 kW and 3,400 kW electric locomotives. Technical requirements for planned overhauls and repairs;

  • NTF 81-007:2009 – Railway vehicles. Technical requirements for overhaul and repair of shock absorbers;

  • OMT 410:1999, on the authorization of testing laboratories and testing of stands and special devices for the verification and testing of railway products used in the construction, modernization, operation, maintenance and repair of railway infrastructure and rolling stock, specific to rail and subway transport;

  • SR EN ISO/CEI 17025:2005 – General requirements for the competence of testing and calibration laboratories;

  • EA-4/02 M: 2013 – Evaluation of the Uncertainty of Measurement in Calibration.


Principle of operation:

The stand is intended to determine the F-S and F-V (damping force-stroke / damping force-speed) characteristics of hydraulic and friction shock absorbers, in particular those which equip railway vehicles, including locomotives and electric frames. The shock absorber is tested in the position corresponding to the normal operating position, respectively in the vertical position or in the horizontal position.

The test stand consists of an actuating module, equipped with an electric motor type ME160-L4-B5-15KW / 1500RPM which drives a mechanical reducer type A602-UH60-7.9-P160, obtaining a nominal speed of output 3.16 Hz. The rotational movement is transmitted to a flywheel actuating a connecting rod whose free end performs a translational movement imposed by a linear guide system consisting of 600mm TKD35-G3-HJ type sliding rails and KWE35-G3-V1 linear trolleys . The linear stroke is obtained from the rotational movement of the flywheel, on the principle of the connecting rod-crank mechanism, the crank arm being adjustable, in the range 0 ÷ 200mm.

Changing the rotation frequency is done with a frequency inverter type ACT401-25 A 15KW, which allows changing the frequency in distinct steps at the level of the electric motor in the range 0÷50Hz, respectively at the output of the reducer in the range 0÷6.32Hz.

The change of the stroke of the test damper is done manually, at the start of the tests, and the frequency is adjusted by software, in distinct steps. The test stroke and frequency are characteristic of each type of shock absorber and are imposed by the technical specification.

The technical performance of the LIMC stand for the shock absorber test is:

  • Maximum length of the shock absorber for horizontal tests: maximum 2000 mm;

  • Maximum length of the shock absorber for tests in the vertical direction: maximum 1500 mm;

  • Maximum stroke: 400 mm;

  • Test frequency: 0 ÷ 5 Hz;

  • Maximum dissipated power: 12 kW.

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