Hubstripping.com

Fichtel & Sachs Torpedo AUTOMATIC (A 2110)

General:

When the AUTOMATIC hub was developed the DUOMATIC hub was already on the market. This was the Wirtschaftswunder (booming economic) years in Germany. Even the sky was no limit anymore. With this background the developers and engineers from Sachs in Schweinfurt had a heroic goal.

Developing a 2 speed hub with a pure mechanical AUTOMATICAL shifting mechanism and without any kind of bowden cables. They achived already a pure mechanical shifting mechanism without bowden cables with the DUOMATIC. Now the next objective was to automate the shifting mechanism.

This was a tricky but the solution was found. The centrifugal force! A force which is was never used again in the history of internally geared hubs.

While reaching a certain rear wheel cadence (rotation frequency) a centrifugal weight moves to a outer position and shifts from gear one into gear two. When you reduce the cadence the centrifugal weight will stay in the outer position and shifts down in the moment you´ll reduce the pedal force.

The shifting point for the AUTOMATIC hub was defined between 16 – 18 km/h. To achive this feature for different wheel sizes there were two versions available:

• Red Version (see picture above) for 20″ up to 24″ rear wheels (centrifugal weight 15 gr.).
• Blue Version (see picture above) for 26″ up to 28″ rear wheels (centrifugal weight 15 gr.).

The shifting point is defined by a little spring which is in contact with one of the centrifugal weights. This means that the centrifugal bodies have the same weight (15 gr./body. I stripped the hubs and checked this!)

This is great because stretching or pushing this little spring makes it easy to optimize the shifting point for your purpose.

When you use the Red version in a 26″ to 28″ wheel the shifting point will be at a higher speed (19 – 20 km/h). The Blue version will shift at a lower speed in a 20″ to 24″ wheel (10 – 14 km/h).

The AUTOMATIC hub is the only hub which uses the centrifugal force to shift between the two gears. The DUOMATIC hub was already a never reached kind of autarkic mechanism with fantastic german Maschinenbau competences indside. Beside the DUOMATIC hub the AUTOMATIC represents the edge of mechanically shifting internal geared hubs.

This hub is the rarest Fichtel & Sachs hub. It was produced since 1966 and only for a few years. The customer prioritized the amount of gears higher than a maintenance and adjustment free hub! The majority of these hubs comes with 28 spoke holes for the Klapprad 20″ purpose. Only a minority with 36 holes. These were hubs were mainly sold in the Netherlands, Denmark and Sweden. There were some all year cyclists in these countries who rated ease of maintenance and adjustment higher than the amount of gears. Two are enough!

The AUTOMATIC internal gear hub owns 2 gears:

Gear 1 Ratio 1:1

Gear 2 Ratio 1:1,36

Reviews / Announcements:

• Pictures and Explosion Drawings (German): Andree Schote is the reference concerning Fichtel & Sachs Torpedo AUTOMATIC gear hubs.
• The internal hub gear review show details on the performance of the AUTOMATIC hub.
• The AUTOMATIC hub was also used for Tandem purpose.
• A interesting Urban Bike concept with the Torpedo AUTOMATIC hub on Ebay.
• The AUTOMATIC hub has the same history like the DUOMATIC kick-back hub. The origin of the hub was the Klapprad (German folding bicycle in the booming 70th of the last century). The market required a “wireless” hub for the Klappräder.

Maintenance / Installation Documents:

• Here are the pics of the original installation and maintenance flyer (Click on the pics to enlarge!).
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Drawings / Spareparts:

• Explosion drawing of the Fichtel & Sachs Torpedo AUTOMATIC internally geared hub.
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Pictures:

• Drawing of the Fichtel & Sachs Torpedo AUTOMATIC internally geared hub.
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• AUTOMATIC hub for demonstration purpose with internal view

Hubstripping:

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• F&S AUTOMATIC hubstrip pictures (seperate slide folder)
  
• AUTOMATIC movie 1(The coaster brake cone moves by turning the pinion backwards into the coaster casing. The casing spreads and touches the inner hub shell. This friction causes the brake effect!)
• AUTOMATIC movie 2( The ratches slide under the ring gear in one direction. In the other direction the ratches take the ring gear with them. These ratches are responsible for the Torpedo sound!)
• AUTOMATIC movie 3(See the switching mechanism of the AUTOMATIC hub. The two centrifugal weights move in synchrony from a central position to an outer position under rotation = second gear. Under a lower rotation frequency a little spring tears the centrifugal bodiess back to the inner central position = first gear)

Links:

• Spareparts and used hubs (German): Jens Hansen is another reference concerning Fichtel & Sachs, SRAM and Shimano hubs.