page_title: Chain boat
section_title: Chain grip-wheel
hierarchical_section_title: Chain boat / Drum winch / Chain grip-wheel
caption_attribution_description: Deutsch: Verlauf der Kette (Kettengreifrad nach Bellingrath)
context_page_description: A chain boat, chain tug or chain-ship was a type of river craft, used in the second half of the 19th century and first half of the 20th century on many European rivers, that made use of a steel chain laid along the riverbed for its propulsion. The chain was hauled by a steam engine mounted on board and enabled the boat to tow a string of barges. In Germany, such a boat was variously referred to as a Kettenschleppschiff, Kettenschlepper, Kettendampfer or Kettenschiff and in France as a toueur.
  The chain was raised out of the water over a boom at the bow of the ship and led over the deck along the ship's axis to the chain engine amidships. The transfer of power from the steam engine to the chain was usually achieved using a drum winch. From there the chain was led over the deck to another boom at the stern and lowered once more into the river. By moving the stern boom and the two rudders, front and aft, from side to side it was possible to replace the chain in the centre of the river again, even when negotiating river bends.
context_section_description: The chain grip-wheel (Kettengreifrad) was designed in May 1892 by Ewald Bellingrath, the director general of the German Elbe shipping company, Kette, in Übigau, in order to overcome the problem of continual chain breakages. This device was used in various chain ships on the Elbe as well as the eight chain boats of the Royal Bavarian Chain Boat Company on the River Main. The idea of the mechanism was to use just one drum or wheel for the actual drive and not to wrap the chain around it several times, but to wind it only partially over the wheel (Diagram 1). The design was supposed to engage the chain securely without letting it slip. It was also supposed to work with different chain thicknesses and lengths of chain link, and independently of their orientation (e.g. angled or on their side). Even if a knot formed in the chain the design was supposed to respond without a problem.
  The chain was engaged in the transmission area by many movable side pins that hooked the chain from the left and right hand sides (Diagram 2). Critics were initially concerned that the many individual moving components of the "catcher" would quickly wear. This fear was allayed, however, by a three-year-long trial that began in May 1892. On the contrary, by using a catcher, the transmission of power was improved so that more barges could be hauled in one string. As a consequence all new chain boats built by Kette in Übigau were fitted with catchers.
  On the River Main, however, the chain grip-wheels were replaced by drum winches again in 1924, because the first ones were too prone to failure.
caption: Diagram 1: Path of the chain over the grip-wheel
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