Hub dynamo

The hub dynamo is a bicycle dynamo which , as a special hub , usually replaces the conventional hub of the front wheel in a bicycle.

History and Development

In 1913 Alois Sanladerer from Ortenburg applied for a patent for a hub dynamo in the USA and was granted it in 1914.

The English company Sturmey-Archer produced hub dynamos for the first time in the 1930s and marketed them under the name Dynohub . Production in England stopped in 1984.

From the 1990s, hub dynamos were further developed and are now standard on trekking and city bikes. In new bicycles, there are hardly any side-rotor dynamos installed. Its suitability for everyday use is high, as it functions independently of the weather and has a higher degree of efficiency compared to the usual side-running dynamos . However, the integration in the hub of the front wheel, compared to side-rotor dynamos, means that a workshop or workshop equipment is required to replace the dynamo if a defect occurs despite the fact that it is largely maintenance-free.

Manufacturers and designs

Hub dynamos are sold by a number of manufacturers, e.g. B.

Schmidt Maschinenbau (SON) (= Schmidt's original hub dynamo)
Renak
Shimano
Shutter Precision
SRAM (from Sanyo )
Sturmey-Archer

There are two basic types of generator:

Gearless hub dynamos: Here, permanent magnets in the hub housing generate a rotating magnetic field through the rotation of the wheel , which induces an electrical voltage in the stator winding (s) installed in the stationary part of the hub . The lighting is switched on via a switch, which is usually integrated in the headlight, or via an electronic control system that automatically switches on the lighting when it gets dark. These dynamos have the highest levels of efficiency in operation, but when switched off they have a low torque loss due to the magnetic reversal losses that occur even when the dynamo is idling (i.e. without a closed lighting circuit) . This type of construction is now almost exclusively found in new bicycles, as it does not require any maintenance and is very efficient.

Hub dynamos which are put into operation via a disengageable gear in the hub. So there are no idle losses . An additional electrical switch is not required. Due to the higher speed of the generator, smaller designs are possible, which also means a lower weight compared to gearless hub dynamos. However, the efficiency is not that high and an automatic switch-on of the lighting in the dark (as with gearless dynamos) is not possible without external power supply.

Due to the high degree of efficiency, there is now a larger range of chargers that use the electrical energy of the hub dynamo to recharge batteries , cell phones and GPS devices or the like via the hub dynamo.

variants

without / with mount for a brake disc
- without a mount for a brake disc - sufficient if a rim brake is installed
- with mount for a brake disc
  - 6 screw holes 44 mm bolt circle diameter (LK) (IS2000)
  - 6 screw holes LK <44 mm
  - 4 screw holes
    - LK 44 mm
    - LK 40 mm
  - Teeth plus lock ring screw (typical System Center-Lock from Shimano, developed for chain sprocket set)
Electrical contacting
- Double flat plug, Manderl on the hub side (in a plane in a circle around the axis; radially symmetrical or slightly eccentrically offset)
  - Cable connection (Weiberl) with double plug or 2 single plugs (4.8 mm standard)
- 2-pole coaxial connector
- Face-to-face contact on both sides through the mechanical hub assembly on contacts on the inside of the dropouts
Spoke mount
- various numbers of holes - often 32, 36; also 24, 28, 40, 48
- various pitch circle diameters approx. 60 - 74 mm
- various axial flange distances often 62 mm; 50-68 mm
Electrical Properties
- StVZO approval
  - for certain wheel diameters (maximum 19 ... 29 inches, 400 ... 742 mm)
  - with certain (LED) headlight types
- 6 V, 3 W.
- Overvoltage protection
- suitable for charging function - via USB 5 V standard
- Magnetic number of poles, e.g. B. 16 - helps determine the flicker frequency
ball-bearing
- Cone, adjustable
- exchangeably press-fitted, sealed prefabricated bearing
Dimensions of the hub without any brake disc, without quick release
- about 309-750 g
Installation width typically 100 mm (for the front)
Fastening typically with an M5 thread quick release (rocker arm or hexagon socket) through a hollow axle
Axle diameter

Mechanical and electrical performance

Compared to pure hubs, hub dynamos are more difficult to run due to their construction, even without the decrease in electrical power. When turning the axle in the hub dynamo or the mounted wheel in the raised wheel fork, a detent can be felt by hand. This is due to the fact that the poles of the permanent magnets and the pole shoes of the coil are alternately facing each other - here there is attraction - and then again on a gap - here repulsion acts.

Mechanically, the individual coils of a free wheel can often be perceived as a slight latching. The bicycle magazine Bicycle Quarterly rated seven different hub dynamos in 2005. With the same drive power, a reduction in speed of approx. 0.1 km / h (lights off) and approx. 1 km / h (lights on) at driving speeds of 10-20 km / h was determined due to the hub dynamo. At higher speeds, the difference becomes smaller, down to a 0.36 km / h difference when driving with the lights on on the flat at 50 km / h.

Most bicycle dynamos generate an electrical output of up to 3 watts and are designed for lighting systems with a nominal voltage of 6 volts. In Germany, these nominal values for hub dynamos with 3 W / 6 V are specified in the Road Traffic Licensing Regulations (StVZO).

literature

Fritz Winkler, Siegfried Rauch: Bicycle technology repair, construction, production. 10th edition, BVA Bielefelder Verlagsanstalt GmbH & Co. KG, Bielefeld, 1999, p. 397, ISBN 3-87073-131-1

Web links

Wiktionary: hub dynamo - explanations of meanings, word origins, synonyms, translations

Commons : Hub Dynamos - Collection of images, videos and audio files

Individual evidence

↑ US patent US1111864
↑ Andreas Oehler: Hub dynamos in the laboratory test. fahrradzukunft.de, April 2006, accessed December 7, 2014 .
↑ Andreas Oehler: New and exotic hub dynamos being tested. fahrradzukunft.de, April 2012, accessed on January 8, 2015 .
↑ Andreas Oehler: Socket on the go - part 3. fahrradzukunft.de, April 2011, accessed on January 8, 2015 .
↑ Compare: Overview of mounting standards for MTB hubs Technical drawings, T. Guba, October 3, 2007, accessed November 29, 2019.
↑ https://www.mtb-news.de/forum/t/bremsscheibe-noch-ein-anderer-standard-ausser-normalem-6-loch-und-cl.637107/
↑ Testing the Efficiency of Generator Hubs (pdf; 380 kB) In: Vintage Bicycle Quarterly Vol. 3, No. 4 . 2005. Retrieved March 22, 2014.
↑ Bicycle: hub dynamo • tec.Lehrerfreund. Retrieved July 2, 2019 .

[1] US patent US1111864

[2] Andreas Oehler: Hub dynamos in the laboratory test. fahrradzukunft.de, April 2006, accessed December 7, 2014 .

[3] Andreas Oehler: New and exotic hub dynamos being tested. fahrradzukunft.de, April 2012, accessed on January 8, 2015 .

[4] Andreas Oehler: Socket on the go - part 3. fahrradzukunft.de, April 2011, accessed on January 8, 2015 .

[5] Compare: Overview of mounting standards for MTB hubs Technical drawings, T. Guba, October 3, 2007, accessed November 29, 2019.

[6] ttps://www.mtb-news.de/forum/t/bremsscheibe-noch-ein-anderer-standard-ausser-normalem-6-loch-und-cl.637107/

[7] Testing the Efficiency of Generator Hubs (pdf; 380 kB) In: Vintage Bicycle Quarterly Vol. 3, No. 4 . 2005. Retrieved March 22, 2014.

[8] Bicycle: hub dynamo • tec.Lehrerfreund. Retrieved July 2, 2019 .