Torpedo freewheel hub
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Torpedo freewheel hub is the brand name of a bicycle - rear hub of the manufacturer Fichtel & Sachs with and without gears with freewheel and coaster brake .
history
The hub has been used in bicycles since the beginning of the 20th century and for many years had by far the largest market share in Germany. In the meantime, it has largely been replaced by imported products and derailleurs . Fichtel & Sachs built this hub shape since 1903, a little later also with a hub gear , an invention by Ernst Sachs after eight years of development, with numerous modifications. For decades it was standard on almost every utility bike. The popularity of the inexpensive torpedo freewheel hub was mainly due to its years of maintenance-free operation. The highest production figures were reached between 1960 and 1980.
durability
Even if the hub gear is very low-maintenance, it is not functional indefinitely. Due to environmental influences (heat, humidity, etc.) and the intentional or unintentional addition of foreign substances, the lubricants in the bearings and the gear parts can harden. This leads to the failure of the shiftability (with manual transmissions) and, in the event of greater stress, to the destruction of the transmission or freewheel hubs.
Most damage to manual transmissions is caused by broken gear or spring parts that are held in the lubricant. As soon as these get between the gears , the planetary gear is destroyed.
With freewheel hubs, the coaster brake sometimes fails or jams, with the result that the chain drive is suddenly dragged along. Hub maintenance should therefore be carried out at regular intervals. The gearbox is completely cleaned and receives new bearing and brake jacket grease. During final assembly, it is important to set the bearing play - if a gear unit is operated with too tight or too loose bearing play, the bearing surfaces can crack, which can lead to bearing or axle breakage.
literature
- Fritz Winkler, Siegfried Rauch: Bicycle technology repair, construction, production. 10th edition, BVA Bielefelder Verlagsanstalt GmbH & Co. KG, Bielefeld, 1999, ISBN 3-87073-131-1