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Sturmey-Archer SW Drei-Gang-Naben: Unterschied zwischen den Versionen
Sturmey-Archer SW Drei-Gang-Naben (Quelltext anzeigen)
Version vom 22. Mai 2021, 17:31 Uhr
, 22. Mai 2021→Sperrklinken: weiter...
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==Was waren die Probleme?== | ==Was waren die Probleme?== | ||
===Sperrklinken=== | ===Sperrklinken=== | ||
Trotze des theoretischen Vorteils des Aufbaus mit drei Planeten, war die SW Nabe in der Praxis recht enttäuschend, inbesondere die Funktion von Sperrklinken und Mitnehmerringe ließ zu wünschen übrig Das häufigste Symptom waren Überspringen unter Last im normalen oder hohen Gang. Interessanterweise produzierte der niedrigste Gang (obwohl hier die Sperrklinken unter der höchsten Last standen) dieses Verhalten sehr selten. Es gibt zwei Gründe für das Überspringen im normalen und hohen Gang: Zum einen können es verschliessene Kupplungsmitnehmer sein (was später beschrieben wird) und im anderen Fall sind es Probleme mit den Sperrklinken. Selbst unter nicht missbräuchlichen Bedingungen entwickeln sie Abspanungen und Einkerbungen und können bis zu dem Punkt verschleißen, dass Sie von den [[Sperrklinke]]n nicht mehr aufgegriffen werden können. Die eigentliche Ursache dieses vorzeitigen Verschleißes hätte bereits während der ENtwicklung bei Tests auffallen müssen, die letztendlich zu diesen Peinlichkeiten im Betrieb geführt haben. Was ist also schief gelaufen?[[Datei:SW-Pawls-issues.png|right|Typische Probleme bei Sperrklingen der SW Nabe]] | |||
This question may never be fully answered, but I'll offer some speculation: The development testing most probably involved some initial hand-built prototypes that did not use production tooling, and as such, were probably machined rather precisely by the best machinists Sturmey-Archer had. Under these conditions, the SW design probably was proven handily, and authorization to go into full-scale production ensued. With production tooling, however, the SW design really fell apart due to the sloppy techniques common to manufacturing plants of the time. Remember, these hubs had to be relatively inexpensive to prove economically viable. Evidence of this abounds when one examines the SW parts. Very rough machining and sloppy fit of most moving parts is usual. (An engineering colleague of mine in our Gear Technology group described the gear machining as "horrible"). This is not meant as a slam against the quality of Sturmey-Archer workmanship: most of the parts are hardened, accentuating the machining marks more than normal, and again, these hubs had to be economical. Also, powder metallurgy was not available as a viable option in 1955. As the old saying goes, "You can have it good, fast, or cheap — pick any two." | This question may never be fully answered, but I'll offer some speculation: The development testing most probably involved some initial hand-built prototypes that did not use production tooling, and as such, were probably machined rather precisely by the best machinists Sturmey-Archer had. Under these conditions, the SW design probably was proven handily, and authorization to go into full-scale production ensued. With production tooling, however, the SW design really fell apart due to the sloppy techniques common to manufacturing plants of the time. Remember, these hubs had to be relatively inexpensive to prove economically viable. Evidence of this abounds when one examines the SW parts. Very rough machining and sloppy fit of most moving parts is usual. (An engineering colleague of mine in our Gear Technology group described the gear machining as "horrible"). This is not meant as a slam against the quality of Sturmey-Archer workmanship: most of the parts are hardened, accentuating the machining marks more than normal, and again, these hubs had to be economical. Also, powder metallurgy was not available as a viable option in 1955. As the old saying goes, "You can have it good, fast, or cheap — pick any two." | ||