60 Jahre Sinn

Endurance test carried out by Fraunhofer Institute LBF in Darmstadt

Fraunhofer_Institute

Sinn watches on rough-road simulation track

How do Sinn watches react to jolts and vibrations?

How do SINN watches react to jolts and vibrations? We wanted a clear answer to this question. And so we fastened them to the steering wheel of a test chassis in the full vehicle test rig at the Fraunhofer Institute LBF in Darmstadt. What followed were exacting tests, and positive results.

Vibrations and possible consequences for mechanical watches

When putting their high-speed vehicles through their paces, motor sport professionals feel naked without a watch on their wrist – even though this subjects the timepiece to considerable stress. If the track is uneven and bumpy, all the jolting and shaking is transmitted automatically from the steering wheel to the watch. Severe shocks and vibrations can have serious consequences for a mechanical movement:

  • the balance spring can become deformed.
  • the impact resistance spring of the balance can become deformed, changing the height of the balance cock on the balance shaft.
  • the dial feet may yield, shifting the dial off-centre and causing the hands to chafe around the centre hole.
  • the seat of the hands can become loose; the hands would then no longer be plane-parallel and could obstruct each other.
  • movement screws can become loose, and with them key components.
Dipl.-Ing. Lothar Schmidt, proprietor of SINN, Dipl.-Ing. Arno Gabel, Head of Customer Satisfaction & Care, Prof. Dr.-Ing. Holger Hanselka, Institute Director, and Dr. Wolfgang Schonefeld, Head of Technical Development at SINN, making preparations.

The Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

To demonstrate how our watches react to shocks, we contacted the Fraunhofer-Institut LBF in Darmstadt. They were to subject the watches to endurance tests carried out on the steering wheel of a test chassis on a simulated rough-road track. The renowned and internationally recognised institute has over 70 years of experience in conducting endurance tests. These provide the scientific basis for all safety-relevant designs such as automobile structures, aircraft wings or rolling stock. Their core competence still lies primarily in system reliability and adaptronics. The research work of the Fraunhofer LBF feeds into the approval conditions for development work carried out by the German, European and American automotive and aircraft industries and their suppliers (visit www.lbf.fraunhofer.de for further information). For the endurance tests we deliberately chose not just rally chronographs but also classic watches such as the Frankfurt Financial District Watch (model 6000). After all – all SINN watches need to be robust and suitable for everyday use!

Tests on simulated rough-road track

The planned tests on the full vehicle test rig at the Fraunhofer LBF in Darmstadt were a first: it is normally cars which are subjected to rigorous tests here under the watchful eye of Dipl.-Ing. Marc Wallmichrath. The SINN watches 757 DIAPAL, 900 FLIEGER, U1000, 917 GR and Frankfurt Financial District Watch 6000 were fastened to the steering wheel of the test chassis for the endurance tests. Drivers' hands intuitively compensate any jolts, and so the watches were mounted on plastic rings to simulate this damping action.

Five SINN watches on the steering wheel, padded with plastic rings. These simulated the damping action which is intuitively produced by a driver
The final check was carried out after the endurance test using an unerring timing machine. The SINN watches passed the extreme impact and vibration tests in the test vehicle with flying colours.

Five watches on the test chassis steering wheel

The first endurance test got under way. How well would the five SINN watches perform? They were facing an extreme endurance test, after all. The test chassis was gradually subjected to ever stronger movements, shaken by powerful jolts and vibrations as if driving along a road full of pot-holes. The steering wheel with the watches had been secured with belts beforehand, as there was no driver in the test vehicle. As a consequence of the simulated jolts, the steering wheel made small but violent movements to the right and left, punctuated by short, relatively motionless phases. The test was designed so that any acceleration to the wrist could be measured, too.

Test passed – everything in order

After two rough test runs – for 30 minutes and 13 hours (equivalent to 300 km) respectively – all eyes turned to the unerring electronic timing machine. This indicated how well the watches had passed the unusual test by taking measurements and making comparisons. “During their 13 hours on the test rig, the watches have experienced 300 km under the most severe rough-road conditions – an ordeal which no test driver could be expected to endure,” said Dipl.-Ing. Marc Wallmichrath. Would the watches' accuracy be compromised, for instance? No, in both tests, the watches performed admirably – test passed with flying colours. Read the report on the next page for more detailed results.

The results in detail

30 minutes into the test, none of the five watches showed any deviation from the time set using the radio-controlled clock prior to starting, or any functional disorders – not even in the hand components. The electronic timing machine revealed only slight changes to the accuracy.

After 13 hours on the test rig – representing 300 km on a hard rough-road surface – four of the five watches showed slight deviations to the original time which had been set from a radio-controlled clock. The deviations were between +1 and -3 seconds. No other effects were detected in the movement.

757 Diapal(.0911)900 Flieger(.1269)U1000(.0369)6000(.2341)917 GR(.0004)
before test30min/13hbefore test30min/13hbefore test30min/13hbefore test30min/13hbefore test30min/13h
ZO3-3/-364/33-1/-24-2/074/4
ZU74/264/353/073/296/4
KU74/043/-265/-282/225/-2
KL74/120/-421/040/-100/-3
Accuracy deviation after 30 minutes00000
after 13 hours10-12-3
ZODial facing upwards
ZUDial facing downwards
KUCrown facing downwards
KLCrown to left

Summary

Despite the enormous stress levels to which our watches were subjected, they all passed both tests with flying colours. This proved their robustness and suitability for everyday use – even when exposed to severe vibration and jolts. As we see, SINN watches are very difficult to shock!

The test conducted by the Fraunhofer LBF in Darmstadt demonstrates impressively just how perfectly SINN watches function – even when subjected to extreme conditions. You can always rely on mechanical watches – especially those protected by innovative SINN technologies. Nevertheless, all types of stress leave their mark and so your should keep it to a minimum by ensuring that you never expose your watch to unnecessary wear and tear.