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Sturmey-Archer SW Drei-Gang-Naben: Unterschied zwischen den Versionen
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Sturmey-Archer SW Drei-Gang-Naben (Quelltext anzeigen)
Version vom 22. Mai 2021, 15:03 Uhr
, 22. Mai 2021→Sperrklinken: Bild hinzugefügt
(→Verschleiß: Bild hinzugefügt) |
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The metallurgy of the parts also played a vital part in the performance of these hubs. On the one hand, the pawls and pawl rings must be made from very hard, high strength steel in order to withstand the extreme stresses (see below) when pedaling hard. On the other hand, such high hardness makes it difficult for the parts to "wear in" together evenly; it's the proverbial Catch-22. It would be interesting to know whether Sturmey-Archer designers ever experimented with various heat treatments on the pawls in order to arrive at an optimum hardness. | The metallurgy of the parts also played a vital part in the performance of these hubs. On the one hand, the pawls and pawl rings must be made from very hard, high strength steel in order to withstand the extreme stresses (see below) when pedaling hard. On the other hand, such high hardness makes it difficult for the parts to "wear in" together evenly; it's the proverbial Catch-22. It would be interesting to know whether Sturmey-Archer designers ever experimented with various heat treatments on the pawls in order to arrive at an optimum hardness. | ||
A stress analysis of a single pawl operating under a 200-pound pedal force is shown in the stress on single pawl animation accompanying animation. The stress levels are extremely high and demonstrate why the pawls typically chip and/or indent. If all three pawls would engage at once, the stress would be reduced by a factor of 3 and the pawls would then probably survive quite well. Under the "overload" conditions, the von Mises stress at the "indent" portion of the pawls is approximately 300ksi, and 800ksi at the tip, if anyone is interested. | [[Datei:Animated sw pawls.gif|left|Animation der Lastverteilung auf den SW Sperrklinken]]A stress analysis of a single pawl operating under a 200-pound pedal force is shown in the stress on single pawl animation accompanying animation. The stress levels are extremely high and demonstrate why the pawls typically chip and/or indent. If all three pawls would engage at once, the stress would be reduced by a factor of 3 and the pawls would then probably survive quite well. Under the "overload" conditions, the von Mises stress at the "indent" portion of the pawls is approximately 300ksi, and 800ksi at the tip, if anyone is interested. | ||
===Verschleiß=== | ===Verschleiß=== | ||
