Scientific American Supplement, No. 446, July 19, 1884 by Various
page 31 of 142 (21%)
page 31 of 142 (21%)
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journey up stream. They are also provided with water ballast tanks, and
under ordinary circumstances they have a draught of 1.3 to 1.4 meters (4 feet 3 inches to 4 feet 7 inches), this draught being necessary to give proper immersion to the screws. When the water in the Rhine is very low, however, the water ballast is pumped out and the tugs are then run with a draught of 1 meter (3 feet 3 3/8 inches), it being thus possible to keep them at work when all other towing steamers on the Rhine are stopped. This happened in the spring of 1882. Referring to our engraving, it will be seen that the wire rope rising from the bed of the river passes first over a large guide pulley, the axis of which is carried by a substantial wrought iron swinging bracket, this bracket being so pivoted that while the pulley is free to swing into the line on which the rope is approached by the vessel, yet the rope on leaving the pulley is delivered in a line which is tangential to a second guide pulley placed further aft and at a lower level. This last named guide pulley does not swing, and from it the rope is delivered to the clip drum, over which it passes. From the clip drum the rope passes under a third guide pulley; this pulley swings on a bracket having a vertical axis. This third pulley projects down below the keel of the tug boat, so that the rope on leaving it can pass under the vessel without fouling. Suitable recesses are formed in the side of the tug boat to accommodate the swinging pulleys, while the bow of the boat is sloped downward nearly to the water line, as shown, so as to allow of the rising part of the rope swinging over it if necessary. The hauling gear with which the tug is fitted consists of a pair of condensing engines with cylinders 14.17 inches in diameter and 23.62 inches stroke, the crankshaft carrying a pinion which gears into a spur wheel on an intermediate shaft, this shaft again carrying a pinion which |
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