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Fortschritte bei der Magnettechnologie haben Nabendynamos deutlich leichter und leistungsfähiger gemacht als die originalen Dynohubs. Die Beleuchtungen sind Dank des Einsatzes von [[Halogen]]- und [[LED]]-Leuchten wesentlich stromsparender und können ein vielfaches an Lichtausbeute erzeugen als klassische Dynohub-Systeme. Die originalen Dynohub Systeme erzeugten eine Leistung von rund 1,8 Watt bei 6 Volt. Die meisten anderen Systeme erzeugen zwischen 2,4 und 3,6 Watt. Die Frontleuchten, die mit den Dynohubs ausgeliefert wurden, waren darauf abgestimmt, mit dieser geringen Leistung möglichst viel Licht zu erzeugen. | Fortschritte bei der Magnettechnologie haben Nabendynamos deutlich leichter und leistungsfähiger gemacht als die originalen Dynohubs. Die Beleuchtungen sind Dank des Einsatzes von [[Halogen]]- und [[LED]]-Leuchten wesentlich stromsparender und können ein vielfaches an Lichtausbeute erzeugen als klassische Dynohub-Systeme. Die originalen Dynohub Systeme erzeugten eine Leistung von rund 1,8 Watt bei 6 Volt. Die meisten anderen Systeme erzeugen zwischen 2,4 und 3,6 Watt. Die Frontleuchten, die mit den Dynohubs ausgeliefert wurden, waren darauf abgestimmt, mit dieser geringen Leistung möglichst viel Licht zu erzeugen. | ||
Ein originaler Dynohub liefert gleichwohl ausreichend Spannung für moderne LED Beleuchtungssysteme. Es existieren inzwischen sogar LED Birnchen, die in die Original-Raleigh-Leuchten passen. Die originalen Birnchen liefern nicht nur weniger Licht, sie sind inzwischen sogar sehr selten geworden. Von Zeit zu Zeit findet man die originalen [[Raleigh]] Dynohubs noch bei schweren Stahllaufrädern von Raleigh-Industries [[Wartung englischer Drei-Gang-Fahrräder|Drei-Gang-Fahrrädern]]. Üblich waren früher 32-Speichen Vorderrad-Laufräder mit dem [[Sturmey-Archer_Naben#GH6|GH6-Dynohub]] oder 40-Speichen Hinterrad-Laufräder mit der [[Sturmey-Archer_Naben#AG|AG Drei-Gang-Nabe]]. Ein guter Funktionstest ist es, einen Schlüssel über die beiden Ausgänge zu halten und das Laufrad zu drehen. Wenn der Dynohub noch in Ordnung ist, fliegen Funken. | |||
Dynohubs erzeugen Wechselstrom. Nabendynamos können im Gegensatz zu Felgendynamos vernünftige Lichtausbeute auch bei niedrigen Geschwindigkeiten erzeugen, weil die Wechselstromfrequenz niedrig ist. Die Birne leuchtet am Strompulshöhepunkt auf. Bei niedrigen Geschwindigkeiten pulsiert das Licht sichtbar, währen das Licht eines Felfgendynamos einfach dunkler wird. | |||
Je höher die Geschwindigkeit des Dynamos wird, desto höher wird die Wechselstromfrequenz. Das ist praktisch, weil die Spule des Generators den Wechseltrom weniger effektiv weitergibt, je höher die Frequenz wird. So wird die Tendenz, immer mehr Spannung bei höheren Geschwindigkeiten zu erzeugen, effektiv ausgebremst. Der induktive Effekt lässt den Nabendynamo bei einer großen Geschwindigkeitsbandbreite einsetzbar bleiben. | |||
Wie auch andere Dynamos kann der Dynohub Glühbirnen durchbrennen lassen, wenn man zu schnell fährt. Fahrradfahrer, die oft sehr schnell fahren, sollten deswegen auf der Hut sein, wenn sie kein modernes Lichtsystem mit Spannungsregulator einsetzen. Ein Nabendynamo erzeugt bei kleinen Laufrädern mehr Strom schon bei geringen Geschwindigkeiten und hier läuft man Gefahr sehr schnell viele Glühbirnen zu verbrennen. Moderene Nabendynamos sind für kleinere Laufräder ausgelegt und dieser Effekt tritt nicht mehr auf. | |||
==Ein Selbstbau-Gleichrichter== | |||
[[Sheldon Brown]]s Artikel stammt aus der Jahrtausendwende. Im folgenden beschriebt er einen primitiven Spannungsregulator, den er ein paar Jahre früher gebaut hat. Wenn man diesen Nachbauen möchte, sollte man beachten, dass der vom Dynohub erzeugte Strom von 0,3 Ampere einen NiCad oder Nickel-Eisen-Hybrid Akku mit einer Kapazität von 10 Ah benötigt, um ein überladen in der "Tag"-Stellung zu vermeiden. | |||
A nickel-cadmium or nickel-metal hydride battery can also over-discharge, suffering permanent damage as the stronger cells drive power backwards through the weaker ones ("polarity reversal"). A "smart" system shuts off charging when the battery is full, and stops discharge at a safe level. Modern generator systems with a stay-on when stopped ("standlight") feature use an LED with a capacitor for storage, to avoid all these issues. | A nickel-cadmium or nickel-metal hydride battery can also over-discharge, suffering permanent damage as the stronger cells drive power backwards through the weaker ones ("polarity reversal"). A "smart" system shuts off charging when the battery is full, and stops discharge at a safe level. Modern generator systems with a stay-on when stopped ("standlight") feature use an LED with a capacitor for storage, to avoid all these issues. | ||
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There is a simple circuit using four diodes, called a "bridge rectifier" that gets around this. It effectively flips the polarity around every half-cycle (an oversimplification, I know) and turns the AC into DC with negligible loss. You could solder four diodes together in the proper configuration, as I did, but these days you can just buy a ready-made "full-wave bridge rectifier". [Considering that the Dynohub operates at low voltages, the loss is significant when using silicon diodes -- 1.4 volts. If you use germanium diodes, it is only 0.4 volts. Fancier circuitry can get the loss much lower yet, but this is only a do-it-yourself project for a serious electronics hacker. -- John Allen.] | There is a simple circuit using four diodes, called a "bridge rectifier" that gets around this. It effectively flips the polarity around every half-cycle (an oversimplification, I know) and turns the AC into DC with negligible loss. You could solder four diodes together in the proper configuration, as I did, but these days you can just buy a ready-made "full-wave bridge rectifier". [Considering that the Dynohub operates at low voltages, the loss is significant when using silicon diodes -- 1.4 volts. If you use germanium diodes, it is only 0.4 volts. Fancier circuitry can get the loss much lower yet, but this is only a do-it-yourself project for a serious electronics hacker. -- John Allen.] | ||
== 1950er Werbematerial == | |||
From a 1952 History of Sturmey Archer: | From a 1952 History of Sturmey Archer: | ||
The Sturmey-Archer Dynohub is truly named:- | The Sturmey-Archer Dynohub is truly named:- | ||
Zeile 55: | Zeile 48: | ||
dynos | dynos | ||
==Wartung eines GH-6 Vorderrad-Dynohubs== | |||
Chris Hayes was kind enough to type up the instructions for dismantling and re-assembly of GH6 Dynohub from "The Secret is Fully Enclosed" the Sturmey Archer Catalogue for 1956. | Chris Hayes was kind enough to type up the instructions for dismantling and re-assembly of GH6 Dynohub from "The Secret is Fully Enclosed" the Sturmey Archer Catalogue for 1956. | ||
[The Dynohub's bearing cups are integral with the hub shell, and can't be replaced. The bearing cones look like those for the AW hub, but they are not the same, as the axle diameter is smaller -- John Allen] | [The Dynohub's bearing cups are integral with the hub shell, and can't be replaced. The bearing cones look like those for the AW hub, but they are not the same, as the axle diameter is smaller -- John Allen] | ||
===Zerlegen=== | |||
Note: these instructions must be followed carefully. Separating the armature from the magnet will permanently weaken the magnet. -- John Allen] | Note: these instructions must be followed carefully. Separating the armature from the magnet will permanently weaken the magnet. -- John Allen] | ||
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Proceed as follows: | Proceed as follows: | ||
# Remove the dynamo-side locknut and washers, making a note of their arrangement so that they can be replaced in their original positions. | |||
# Remove the four magnet-fixing nuts and lock washers from the back of the hub drum, and then remove the four magnet-fixing screws. | |||
# Hold the wheel, with the dynamo downwards, just above the work-bench. A few light taps with a mallet on the end of the spindle will cause the dynamo unit to drop out complete. | |||
# The magnet spacing ring can now be lifted out of the hub drum. | |||
# Unless it is essential to do so, the armature and magnet should never be separated. If they are to be separated, a keeper ring is absolutely necessary, because the magnet will lose some of its magnetism unless there is always iron inside it. Even a moment's separation will cause loss of magnetism, and a spanner placed across the magnet is useless as a substitute for a keeper ring. To separate the magnet and the armature, hold the dynamo unit in the left hand, with the terminal plate against the palm. Then fit a keeper over the armature and lightly tap the keeper with the palm of the right hand. The magnet will slide off the armature and on to the keeper. At this stage it is wise to test the armature with a test meter. If there is no reading on the test meter there is a break in the winding. If a test meter is not available, a battery and bulb may be connected as shown in the diagram, and if the bulb does not light a break in the armature winding is indicated. A second test is to disconnect the lead from one of the armature terminals and touch the outer edges of the armature with the bare lead. If the bulb lights, this indicates a short circuit. | |||
# Remove the cone locknut on the left-hand side and unscrew the left-hand cone. | |||
# The channel-section dust cap is just a press-in fit and can be prised out with a wide screwdriver (to avoid damage). The ball cage may be lifted out for examination of the hub bearing surface. If a new ball retainer and balls have to be fitted, it is usually best to fit a new dust cap as well. Both hub cups are part of the hub shell and if either is worn a complete new shell must be fitted. | |||
# The spindle may now be pulled out from the dynamo side,together with the right-hand cone. If the bearing surface is in good condition and the spindle threads are sound, there is no need to remove the cone. | |||
# The ball cage may be lifted out for examination of the hub bearing surface. | |||
SPECIAL NOTE. - GH6 hubs prior to 1952 had the adjusting cone on the dynamo side. This cone is extended to pass through the armature body and is flatted at the outer end to take (K428) notched adjuster washer, by means of which the cone may be turned. Dismantling instructions from 1 to 5 remain exactly the same as for the current model. For paragraph 6 read 'Unscrew the dynamo-side cone and lift the ball cage out of the hub shell. The spindle may now be pulled out from the other side, together with the fixed cone.' All further comments apply equally to all GH6 hubs. | SPECIAL NOTE. - GH6 hubs prior to 1952 had the adjusting cone on the dynamo side. This cone is extended to pass through the armature body and is flatted at the outer end to take (K428) notched adjuster washer, by means of which the cone may be turned. Dismantling instructions from 1 to 5 remain exactly the same as for the current model. For paragraph 6 read 'Unscrew the dynamo-side cone and lift the ball cage out of the hub shell. The spindle may now be pulled out from the other side, together with the fixed cone.' All further comments apply equally to all GH6 hubs. | ||
===Zusammenbau=== | |||
Proceed as follows (see notes at end if hub was supplied before April 1952): | Proceed as follows (see notes at end if hub was supplied before April 1952): | ||
# Fit the ball cage with the ball-retainer ring facing outwards, into the cup on the left-hand (the smaller) end of the hub shell. If a new ball-retainer is being fitted, the dust cap also should be new. | |||
# Fit the dust cap, with the channel facing outwards, and press it home (or tap lightly with a hammer). | |||
# If the dynamo-side cone has been removed from the spindle, replace it (LB357AZ) on the spindle and screw it up tight against the shoulder on the spindle. | |||
# Fit the ball cage, with the ball retainer ring facing outwards, into the cup on the dynamo-side of the hub shell. | |||
# Insert the spindle into the hub shell from the dynamo-side. | |||
# Fit the left-hand cone and adjust the hub bearings as described in The Fitting and Adjustment of Sturmey-Archer Hubs. (A correctly adjusted wheel must have a slight trace of play at the rim.) | |||
# Fit the cone locknut and screw it up tight against the left-hand cone. | |||
# If the magnet and armature have been separated, take the magnet and keeper ring in the left hand and, with the right hand, lay the armature alongside it. | |||
# While holding the magnet with the chamfer facing outwards, push the armature and the keeper through so that the magnet slides from the keeper on to the armature. | |||
# Fit the card disc (carrying patent numbers) inside the cover plate, with Its notches opposite the magnet notches. | |||
# Fit the cover plate over the magnet, chamfer inwards, making sure that the four holes in the cover plate are in line with the notches in the card and the magnet. | |||
# Fit the metal spacing ring into the hub shell. | |||
# Fit the shim washer over the cone. | |||
# Push the complete dynamo unit into the hub shell, making sure that the holes in the cover plate are in line with those in the hub shell. | |||
# Fit the magnet fixing screws, washers and nuts. | |||
# Fit the spacing cup, washer (if any) and dynamo cone locknut in the arrangement noted when dismantling. | |||
==Ersatzteile sind nicht mehr verfügbar== | |||
No replacement parts are available for GH6 Dynohubs. Please do not write to me asking for Dynohubs or parts; I don't have any, and I don't know where you can find any. [If you want to rebuild one, have a spare on hand for parts. -- John Allen] | |||
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==Siehe auch== | |||
The Sturmey-Archer AG 3-speed rear Dynohub | The Sturmey-Archer AG 3-speed rear Dynohub | ||
Reflectalite is a supplier of replacement lamps/bulbs for Dynohubs. | Reflectalite is a supplier of replacement lamps/bulbs for Dynohubs. | ||
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==Quelle== | ==Quelle== |