Chain boat

Chain tugboats (including chain tractors, track- liners, chain ships or French toueur called ) were in the second half of the 19th and in the first half of the 20th century used on many European rivers ships that ran along a laid along the riverbed steel chain forward and the chain shipping justified. The driven each by a steam engine riverboats attracted several barges along behind him.

The chain was lifted at the bow of the ship an extension ( jib ) out of the water and out on the deck along the ship's axis to the chain drive in the middle of the ship. The power transmission from the steam engine to the chain was mostly a drum winch. From there, the chain carried on the deck at the stern and to the boom back into the river. The lateral mobility of the boom and the two both front and rear mounted rudder, it was possible to store the chain even at river bends again in the middle of the river.

• 5.1 Water Turbines
• 5.2 paddle and screw propulsion

History

The chain shipping revolutionized the beginning of industrialization in the second half of the 19th century, the inland waterways and solved the from the then standard towing. The chain drive chain steamer took the small power of the former steam engines from optimal. In addition, the ships were especially adapted to the difficult conditions of the rivers this time with strong currents and shallow water. This led to the spread of chain shipping on many rivers in Europe. In the first half of the 20th century, the increasingly powerful Radschleppdampfer ousted the chain steamer, especially the channeling of rivers, the advantages of the paddle steamer further reinforced.

Initial developments and technical precursors of chain ships existed until the mid-19th century, especially in France (→ Main article: chain shipping ). For the prototype of all subsequent chain steamer on the Elbe, Neckar and Main, the French chain steamer " La Ville de Sens " which was built by the German engineer M. Dietz in 1850 in Bordeaux and on the upper Seine between Paris and Montereau was used was. His technically very well-developed functional principle and mechanical equipment have become the model for all later European chain steamer.

Shape of the hull

The deck of the symmetrically constructed vessels reached down almost to the water surface at the bow and stern of the ship. This design reduced the force necessary to lift the tow chain on the bow of the ship, thereby also reducing the draft at the bow of the ship. The greater height in the middle of the ship simultaneously allowed an easier accommodation of the steam engine. This form of the ship deck is typical of all later built chain tugs.

Chain tugs were preferably used on rivers with low water depth and strong currents. This results in the flat, even bottom of the vessels. For very low water depth optimized chain ships unladen had a draft of only 40 to 50 centimeters. Fully loaded with coal, the depth increased to about 70 to 75 centimeters. This shallow draft allowed the water transport in dry summer months when the water level of the rivers could be very low.

Shorter chain vessels (length 30 to 40 m, width 5 to 6 m) ​​were more maneuverable and had advantages on narrow rivers with many bends, for example, on the Saale. Longer chain vessels (length 45 to 55 width 7-10 m m ) were on rivers advantageous to have a relatively large water depth, such as the Elbe. The deeper a body of water, the greater is the proportion of the force which must be applied for eliminating the heavy chain. The bow of the ship is more pulled down. For larger chain vessels, this effect is less.

The hull itself was made ​​of iron or wood and could withstand light groundings. Were there still a leak, so the hull inside was additionally separated by more watertight bulkheads in enclosed areas that prevent the sinking of the ship. Below deck were located next to the steam engine and the coal bunkers and the crew quarters of the crew.

Control and navigation

In the chain, the chain was shipping over long distances of several hundred kilometers only, loose ' in the river bed. Only the weight of the massive chain of about 15 kilograms per meter or 15 tons per kilometer and the natural entanglement with sand and stones in the river bed was enough as a counter bearing, so that the chain tugs could entlangziehen with the attached barges on the chain. The water carried the weight of the ships, while the chain had to take only the driving force. An anchor chain was only at the two extreme ends of the route, so that the ships could also drive up there.

A problem was rather the lateral transfer of the chain dar. on river bends is a tendency for the curved chain moved more and more "straight" to draw and thus continue to move towards the city shore. To prevent this, the chain ships were fitted front and rear with large, powerful rudders. These oars were partly a length of about four meters and were operated using befindlicher on deck steering wheels.

At the ends of the vessel, the chain for further guidance on boom, which jutted out beyond the ship ran end. This prevented a collision of the chain with the long oars. The cantilevers were mounted movably and could be pivoted about a hand crank sideways. This allowed the ship to be oriented obliquely to the chain direction. Also, this improved the opportunity to take the chain back in the middle of the river.

The cantilevers were also equipped with a chain -termination system to prevent run-off in a continued fraction of the drag chain. Could not be hooked fast enough in the chain of blocking hook, the chain ran off and disappeared into the river. They then had to be laboriously isolated with a search anchor and secure.

Chain drive

In the first generation chain tugs on the chain attached to the side of the ship chain reels ran. With very strong currents or problems when lifting the chain due to silting or through obstacles on the river bottom as large stones, the ship could vary significantly and get flip side. On subsequent chain tugs the chain drive was therefore always placed in the center of the vessel.

Drum winch

The older chain tugs on the Elbe, the chain steamer on the river Neckar and the three to the Hessian Main chain AG belonging chain tugs on the Main used a drum winch for power transmission. In order to ensure the necessary adhesion of the chain on the driven pulleys, the chain in the middle of the vessel was wrapped several times around two successively arranged Zugtrommeln. The chain running in the four or five grooves and was performed alternately on the front and the rear pulley.

Disadvantage of this method were numerous Kettbrüche. This did not occur for instance by an overload on the Wegkette by the size of hauls. To this effect has been calculated that even with a wear of the chain links to half of the original cross-section, this force would not have led to a break.

Instead, the front drawing drum used by friction from each stronger. But as soon as the diameters of the two drums were unequal, longer chain wrapped on the rear drum, than could be handled at the front. This produced on the drums and tensions between them that could be so large that the chain links of this tensile load could not withstand, and the fracture limit was exceeded.

Particularly problematic was this effect, when the chain had twisted in itself, ie came to the edge or even a knot had formed. Thus, the Umwicklungsradius be enlarged by up to 25 %, and even at 5%, the elastic limit of the chain was reached.

The transfer of the drag force of the drums on the chain was carried out only by friction. In case of frost or ice formation, the chain could slip through. This made ​​do with hot water, which was poured over the drums.

Another problem with the drum winches was the relatively large chain length of 30 to 40 meters, which was necessary due to the multiple wrapping of the two drums. If the crawler tractors used only for the ascent, so this chain quantity could not be simply discarded, otherwise after a certain operating time, the entire chain above the actual operating range would be accumulated and would be missing at the beginning. This evil one tried to counter the fact that the chain tug on the descent always use a proper piece of chain and took down the valley at the beginning of the chain einfügte again. This resulted in a continuous migration of the chain, which made an inspection of the wear in high-risk sections of the river as the rapids difficult. In particular, deliberately wandered used, reinforced chain sections continues uphill. Also jettisoning the chain at the meeting of two traveling on the chain chain vessels was relatively difficult due to the multiple round the two drums.

Many of the chain steamer own without additional drive had for the mountain and descend a different translation. For the ascent, this was designed for high traction, while a higher speed could be achieved on the descent.

Kettengreifrad

The Kettengreifrad (also called Kettengreifrad after Bellingrath ) was established in May 1892 designed by Ewald Bellingrath, the Director-General of the German Elbschifffahrtsgesellschaft "chain" in Übigau to avoid the problem of continuous continued fractions. This principle was used by various chain ships on the Elbe, as well as a total of eight ships of the Royal Bavarian chain chain shipping company on the Main.

The idea of the mechanism was to use the actual drive only a drum or a wheel and not herumzuwickeln the chain several times, but to embrace only partially ( Figure 1). The design should capture the chain securely without slipping the chain began. This should also at varying strength of the chain and different lengths of the individual chain links and (eg, oblique or edgewise storage) function regardless of their location. Even compared to a knot formation occurring in the chain, the design should respond without error.

The chain was fixed in the drive area over many lateral pins ( gripping device ), the linking arms as moving parts left and right in the chain ( Figure 2). Critics feared at first that the many moving parts of the " gripper " could be worn quickly. This fear could however ( started in May 1892) in a three-year trial be refuted. By using the " gripper " could be improved on the contrary, the power transmission so that more ships could be transported in a towed convoy. As a consequence, all new buildings of chain tugs society chain were fitted in Übigau with gripping wheels.

At least with the chain ships on the main chain of the gripping wheels were replaced again from 1924 through drum winches, as the former were too prone to failure.

Electromagnetic drum

Another approach to reduce the amount of continued fractions and the migration of the chain comes from France and was used from November 1892 on the lower Seine at Paris. The inventors developed a technique de Bovet to increase the friction of the chain on the driving drum by magnetic forces. Again, the chain lies at only three-quarters of wrapping on the pulley. The fixation of the chain in the tension pulley carried by magnetic forces, induced by the electromagnets, which were incorporated into the pulley. The requisite power generated its own motor and an approximately 3 -horsepower dynamo.

The magnetic force handed despite small wrap of the pulling roll out in an experiment with an old, 9 kg per meter heavy chain to produce a holding force of about 6,000 kg.

Additional drives

In addition to the chain drive most of the ships were built later chain possessed an additional drive. This allowed the movement of the ships without chain, which was mainly used during the descent. The talwärtige travel time was reduced by higher travel speeds and eliminating the time-consuming and complicated encounter between uphill and downhill driving on the same chain ships. Additionally, the chain has been spared.

Water turbines

From 1892 water turbines were used according to Zeuner at chain ships on the Elbe. You are a forerunner of today's water jet propulsion. But addition of the faster decline of the additional driving also enabled direction corrections while driving on the chain and facilitated turning maneuvers. Chain vessels with water turbines were some chain ships the same and at the Bavarian chain ships on the river Main in use.

The water is sucked through two rectangular inlet openings in the side wall of the chain steamer. It then passes through the distributors in the interior of the hull turbine. The turbine accelerates the water and forces it through the rearward facing side of the water outlet openings in the vessel wall. The flowing water drives the ship forward (top side view ). To change the direction of the deflection curve ( reflector ) is pivoted and so the water in the opposite direction redirected (lower panel of the side view). The pumping direction of the turbine, however, always remains the same.

Each chain steamer was equipped with two of these water turbines, which were located on the port side and starboard side. At a turning maneuver, the water shone on one side and forward on the opposite side of the ship backwards, thus ensuring the rotation of the ship.

Paddle and screw propulsion

Due to the strong current of the river Danube, the Chain ships could not go downhill here on the chain. Should the chain tugs are suddenly forced to hold ( for example, by a continued fraction ), the risk was great that ships auffuhren rear to the front and so it was a disaster. They had therefore. , As an additional drive for decline large side paddle wheels, which were driven by steam engines with a capacity of up to 300-400 hp

The third type of auxiliary drive the screw drive is mentioned. This type of add-on drive was used in part on the Danube to decline to allow in this direction towing.