B Before taking up the strictly modern machines so largely used now in the final processes of rope-making—the forming of strands, laying of common ropes and closing of cable-laid goods—we shall describe the ropewalk method of performing these operations as it is practised today.
For making tarred goods in all but the smaller sizes the walk has certain advantages not afforded by more advanced methods. It also provides efficient equipment for turning out the largest ropes, which would otherwise require special machinery.
The long alleys or grounds where the work takes place are usually laid out in pairs, one for forming, the other for laying and closing. Each ground has a track to accommodate the machines and an endless band-rope which conveys the power.
At the head of the forming ground stand frames holding the bobbins of yarn. The yarns for each strand first pass through a plate perforated in concentric circles. This arrangement gives each yarn the correct angle of delivery into a tube where the whole mass gets a certain amount of compression.
CORDAGE MANUFACTURE BY THE ROPEWALK METHOD
YARNS PASSING FROM BOBBINS THROUGH PERFORATED PLATES
“TOP TRUCK”—LAYING PROCESS
FORMING MACHINE—MAKING STRAND
CLOSING TARRED RUSSIAN HEMP CABLE 15¾″ CIRCUMFERENCE FOR ARGENTINE BATTLESHIP “RIVADAVIA”
The forming machine—a heavy carriage surmounted by the band-rope wheel into which are geared several spindles and a driving drum—is now drawn up, and each group of yarns is attached to a separate spindle as shown opposite. A rope made fast at either end of the walk is given a few turns around the drum, the band-rope is set in motion and the machine moves off, leaving in its wake the compactly twisted strands.
In the case of a common right-laid rope, the forming twist is left hand. A change to right hand can be made simply by shifting clutches. The amount of turn or twist depends on the diameter of the drum, which is adjustable.
Behind the machine follows a man who swings out the stakes, placed at intervals along the walk, and throws the strands over them. When the process is completed the strands are cut away at either end and transferred to the laying ground, the stakes being pushed back to allow the return of the forming machine for another trip.
The two laying machines stationed at opposite ends of the walk greatly resemble the forming machine. One—usually the “afterturn,” so called—is made fast; the other, or “foreturn,” is braked down but not secured. The strands are attached to separate spindles on each machine and given a little extra twisting from both ends—left hand as in the forming. During this process of putting in the “hard,” so called, as well as in the laying itself, the foreturn machine is drawn slowly ahead by the shortening of the strands.
For the laying, the ends of the strands at the afterturn machine are transferred to a single spindle. The “top”—a cone-shaped block containing a groove for each strand and mounted on a light truck—is backed up to the machine, the strands are inserted and the twisting recommenced, the direction of the afterturn spindles now being reversed. The resulting tendency of the strands to untwist is counteracted, partly by a left-hand revolution of the foreturn spindles, and partly by the presence of the “hard” or surplus twist just described.
As the top truck is forced ahead by the twisting process, the rope-maker preserves a correct lay in the rope by means of greater or less leverage on the “tails”—the loose ropes shown in our picture. The stakes on which the strands rest are removed one by one to allow the top truck to pass and are then replaced to support the rope until the laying is finished and the reeling in of the rope begun.
The closing process on cable-laid goods is like the laying except that the twist is reversed. The work being with three complete ropes—frequently very large—a heavier top truck is necessary, and this must often be ballasted, as shown in our illustration on page 80, to keep down the vibration which would otherwise tend to lift the truck off the track.