THE COLLIERY GUARDIAN AND JOURNAL OF THE COAL AND IRON TRADES. Vol. CVII. FRIDAY, MAY 29, 19U. No. 2787. The Coiling of Winding Ropes on Drums. By HUGH BRAMWELL From the Proceedings of the South Wales Institute of Engineers. Under ordinary conditions and for moderate depths, so long as the old rule of 100 to 1 for the drum diameter is adopted, it is hardly necessary to specially consider the coiling of the rope, there being usually plenty of room on the drum to carry the amount of rope required. With greater depths and larger ropes, in order to keep down the diameter of the drum, it is necessary to con- sider the coiling of the rope, and sometimes to make special provision for this. The natural lead of a rope from the pulley to the drum is the line from the point at which it leaves the pulley rim, at right angles to the axis of the drum shaft fig. 1. Turning the pulley as in fig. 2, or the drum as in fig. 3, makes no difference to this. The rope, unless pre- Fiq. 1. Fig. 2. Fig. 3. 90> >.90* but it has been considered necessary to only use locked coil ropes (smooth surface). The average of 14 ropes working under these conditions is 22-J months’ life, 154,982 tons of coal per rope, cost e215d. per ton of coal.. With a plain surface, therefore, the only way to increase the capacity of the drum for rope is to increase its diameter, and this soon leads to drums of enormous size. Increasing the capacity by adding to the width instead of adding to the diameter would generally have many advantages, and within limits this can be done by “ grooving ” the barrel and utilising a part of the space a a, as in fig. 5. The “ grooves ” deflect the rope out of the line of its natural lead, between a and A, just as the coils of the rope on the plain barrel deflect it between A and C.< The maximum size of angle A Ba is, so far as the writer is aware, largely undetermined. Conical and cylindro-conical drums take advantage of their grooving in this way, and are generally arranged but with proper arrangement this is not in practice found to be very material. Many ropes are running where the wear from side friction at the point C, fig. 4, is greater than would be incurred by overlapping the rope on itself. When overlapping is adopted it is essential that the rope, having completed one layer of coils on the barrel and reached the flange of the drum, should be raised up to recoil on the first layer, without being squeezed between the last coil on the barrel and the flange. In its simple form the “ filling-in ” strip, as it may be vented, will always try to leave the drum on this line. It is, in fact, the shortest possible line between the pulley and the drum, and therefore must be the natural lead. At first sight it might appear as if “ coning ’’ the barrel of the drum would alter the natural line of lead, but a little consideration will show that this is not so. Coning the barrel can, however, produce a “ fleeting ” motion of the rope towards the small diameter, which may sometimes be of use. With a pair of ropes on a plain cylindrical drum, the maximum space available for coiling is the width between the pulleys A D, as in fig. 4, and this space is further restricted by the permissible angle ABC. With single lines of tubs or trams on the cage deck, this maximum space A D may in practice vary from D C Fig. 4. D C Fig. 5. A . a a' Section at C Section at A Section at B Fig 6. D C Fig. 7. Section at D Section at E Fig. 8. 4 ft. 6 in. to 5 ft. 6 in. or thereabouts. With double lines of tubs or trams per deck, the distance between the pulleys may reach 9 ft. 6 in. or more. In such a drum with a plain surface it is nearly useless making the space Aa more than is necessary to carry the dead coils of rope, as the latter will always tend to leave the drum at A in the plan A B. The permissible size of the angle ABC, fig. 4, depends on the side friction of the rope against itself at C, and with the ordinary make of rope is usually limited to 2degs., or one in 29. The writer has one case in mind where, with a comparatively small load (four tons —500 yds.), the angle has been reduced to one in 25|, as in figs. 6 and 7, in order to provide the largest rope capacity with the smallest diameters compatible with the life of the rope. . Having thus fully utilised the space Aa, the capacity of the drum is again at its limit, and can only be increased by increasing its diameter, or by overlapping the rope on itself. In this, country and oh the Continent for vertical winding there has been a natural disinclination to over- lapping round ropes on themselves, notwithstanding that it is the universal practice in haulage work, even with heavy gradients, heavy loads, and men riding. It is, however, commonly adopted under the heaviest condi- tions of vertical winding in American and South African mines. The great depths of the South African mines has almost forced its adoption, and there drums so arranged are apparently generally preferred to systems of endless rope winding, such as the Koepe or Whitting. There is, of course, some additional wear on the rope, Fig. 11. Fig. 12. called, necessary to so raise up the rope, must take the shape shown in the sketches given in fig. 8. The rope commences to rise on the strip at A, eventu- ally reaching E, its full diameter above the drum barrel after passing through the phases BCD. In practice the sharp edges of the strip would be rounded off, and in the case of a grooved barrel the several sections at A B C D E in fig. 9 would result. It will be seen that the correct form for this raising part of the rope barrel depends on the diameter of the rope and that of the drum. It can always be set out graphically for each particular case. It is at position E, fig. 9, that the risk of overlapping comes in. Coil 4, instead of dropping into the space between two previous coils of the first layer, as in fig. 10, may run wild across the previous layer in its tendency to leave the drum at the natural lead, and thus the rope would fail to utilise part of the drum capacity. sr-zuo' 'in 28 Fig. 13. J CP A^' 7^42 Fig. 14. 94 'in cu C C' A 36"--' The limiting size of the angle AB C, fig. 11, as applic- able to the overlapping coils, is again, so far’as the writer is aware, undetermined. It is with the object of giving and obtaining informa- tion on the maximum permissible size of the angle A Ba for the grooved barrel, and ABC for the over- lapping layer, that these few notes are presented. Taking fig. 11, the limiting size of the angle A Ba would depend chiefly on the depth of the grooving and the friction permissible between the rope and the edge of the groove. It is the practice of drum makers to adopt a depth of groove of one-third of the diameter of the rope, with a pitch y-g- in. or in. greater than the rope diameter, presumably thus allowing for slight variations on the normal rope diameter, and to somewhat eliminate side friction of rope against rope.