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Sturmey-Archer SW Drei-Gang-Naben: Unterschied zwischen den Versionen

(→‎Springless pawls: Überschrift)
Zeile 38: Zeile 38:


==Sperrklinken ohne Federn==
==Sperrklinken ohne Federn==
 
Das bei weitestem berüchtigtste Merkmal dieser Naben waren allerdings die federlosen Sperrklinken. Diese kleinen Schmuckstücke aus Irritation sind freischwebend, halbmondförmig und aus gehärtetem Stahl (ungefähr 7,5mm lang und 4,8mm breit) gefertigt. Sie ähneln einer Scheibenfeder, wobei die normalerweise gerade Oberfläche hier gekrümmt ist, so dass diese einem Halbmond oder Lächeln ähnelt. Sie werden dazu benutzt, Drehmoment in die eine Richtung zu übertragen und ermöglichen freilaufen lassen in die andere Richtung.  
By far, the most notorious feature of these hubs, however, is the springless pawls. These little gems of irritation are free-floating, crescent shaped, hardened steel a mere 3/10ths of an inch long by 3/16ths of an inch wide. They resemble a Woodruff key, except that the normally flat surface of a Woodruff key has been curved, resembling a crescent or smile. They are used to transmit torque in one direction and allow freewheeling in the other. The freewheeling is accomplished by a rocking action imposed by the passing ramps and valleys of the right or left ball rings — it's actually quite clever and reminds one of the classic escapement mechanisms of mechanical watches and clocks. While coasting, these pawls are nearly silent to the rider, but spinning the wheel with the bike off the ground and your ears nearby will usually produce a noticeable ticking sound.
The freewheeling is accomplished by a rocking action imposed by the passing ramps and valleys of the right or left ball rings — it's actually quite clever and reminds one of the classic escapement mechanisms of mechanical watches and clocks. While coasting, these pawls are nearly silent to the rider, but spinning the wheel with the bike off the ground and your ears nearby will usually produce a noticeable ticking sound.


In the drive direction, the arrangement of ramps and valleys serves to pick up one edge of each pawl and jam it in place against the valleys in the ball ring, preventing relative rotation of the pawl carrier and the ball ring. There are 3 pawls in action in any given gear selection, again to evenly distribute the drive forces. They are much smaller than AW pawls, but since they were designed to be engaged 3 at a time instead of 2, they are presumably sized to be more-or-less equivalent in strength.
In the drive direction, the arrangement of ramps and valleys serves to pick up one edge of each pawl and jam it in place against the valleys in the ball ring, preventing relative rotation of the pawl carrier and the ball ring. There are 3 pawls in action in any given gear selection, again to evenly distribute the drive forces. They are much smaller than AW pawls, but since they were designed to be engaged 3 at a time instead of 2, they are presumably sized to be more-or-less equivalent in strength.
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