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January, 1944

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From the earliest days of mining until as late as 1881 coal was wound to the surface in corves, or baskets, constructed from hazel rods. With the introduction of the steam engine for pumping, winding and other mechanical duties, it became possible to win coal at greater depths which resulted in larger outputs from individual shafts. To deal with these outputs the corves were increased in size until their capacity reached 5 and 6 cwt. of coal. Owing to the then impossibility of high velocity winding in the shafts, it became necessary as the shafts deepened to wind with two or three corves attached to the rope at short intervals apart. The corves were still permitted to swing freely in the shafts and collisions were a frequent occurrence. The first effort to prevent such collisions was the partitioning of the shaft from top to bottom, one half for the ascending and the other half for the descending corves.

For winding men and boys the "clatch iron," already illustrated, was often used. When corves were introduced, winding was still very primitive in character, and it was the custom for the men and boys to either stand in the corve, sit with a leg in the loop of the chain, or to cling on to the rope. It is not surprising that distressing accidents were frequent.

The first and most important improvement in winding practice was the introduction, by John Curr in 1788, of a system of guides in which worked a cross bar to which the corve carrying the coal or men was attached. This system became common in the Sheffield area, especially where the shafts were shallow, but as only one corve or carriage could be attached to the bar, the output was definitely limited and its use was unsatisfactory when the coal had to be wound from greater depths. The system had also the disadvantage of needing a moveable platform in order to land the full corve at the surface, although later, efforts were made to use mechanical contrivances to overcome this difficulty.

In 1835, Hall instituted his arrangement of guides and cages at Ryton-on-Tyne. The cage was rectangular in shape, constructed of wrought-iron bars, with a wooden floor to which were attached rails for the pit tubs. In 1844, a cage was used at Cowden Colliery, Dalkeith, which consisted simply of a platform supported from the flat winding rope by chains attached to iron uprights, which carried shoes that embraced the wooden guides. In certain areas this type of cage is still used in America, with the addition of a hood only.

Early types of cages used in 1850-1860 are illustrated in Figs. 1 and 2. In Fig. 1 is shown a cage with a wooden floor to which is attached four wrought iron uprights, surmounted by a metal pyramid roof. The shaft for this type of cage was fitted with two wooden guides only. The cage had four channel-shaped slippers, two on each side fitted at the top and bottom of the cage. Although this type of cage made for more speedy winding and increased safety to men and boys riding, the possibility of accidents was always present.

The cage in Fig. 2 is an improvement on the previous type. This cage, introduced about 1860, in addition to having four vertical uprights, had also diagonal cross pieces to strengthen and stiffen the structure. To prevent the occupants of the cage coming in contact with the slippers and guides, which were similar to those of the cage shown in Fig. 1, sheet iron was attached to the two sides. This was a definite step to greater safety.

The first mention made of a double-deck cage was the one designed by Hampshire in 1862. That shown in Fig. 3 is a model of a two decker cage designed by Harper in 1869; excepting for the side covering plates and such refinements as cage gates, tub holders, etc., this cage is very similar to the ones which are at present in use at many collieries. It will be noticed that rope guides were used for this cage.

As improvements were made in coal winding practice, similar progress was made in the metalliferous mining industry. A common system of skip winding used in Cornwall about the year 1862 consisted of a sheet iron skip which ran on four rollers and had four projecting plates beneath it to keep it on the guides; the skip had a hinged door in front with a gravity-locked bolt. Where the shaft followed a lode on the dip, it was more often than not very crooked; consequently, the skip was often fitted with rollers, in addition to the slippers in these conditions, in order to reduce friction at the curves. These primitive types were the forerunners of those used today, both in coal and metal mining, typical illustrations of which are given in Figs. 4 and 5. Fig. 4 illustrates the Brown-Boveri overturning skip, and Fig. 5 the Demag tipping skip which has guide shoes at the front and back of the suspension frame, thus making it impossible for the skip to be displaced from the vertical whilst travelling in the shaft.

An important feature of the skip which was early recognised in metalliferous mining is the higher useful load, since the dead weight of the tubs has not to be considered. Consequently, for the same size of rope, a greater load can be carried, or, for the same load as carried by a cage, it is possible to reduce the size of rope, pulleys, drums and winding engines, which means reduced cost of installation and maintenance. There is no doubt that just as the cage succeeded the corve with the introduction of mining coal at increased depths, so with the diminution of our coal reserves at moderate depths and the necessity for still deeper mining, the tendency will be for the skip gradually to replace the cage.

Cage fittings

The quality of steel formerly used in the manufacture of winding ropes was not comparable with that made today, and for some time after their introduction, in 1840, there were many accidents due to ropes breaking. In many areas, especially in the North of England, the men raised many objections to their use, as is illustrated by various legal actions and petitions. In 1843, the workers at Wingate Grange Colliery, for instance, entered a case for trial at the Durham Assizes, and in 1844 the men at Jarrow Colliery petitioned Parliament against the use of wire ropes. The opposition of the miners against the installation of wire ropes was gradually overcome, and with improvement in manufacture and additional experience in their use no further objections were raised after 1845.

With the added introduction of guides and cages and, therefore, increased winding speeds, the middle of the nineteenth century marked a period when many devices were designed with the object to increase winding safety.

In 1844, the pioneers of wire ropes, appreciating that these were much more rigid than the previously used hemp ropes, introduced springs in order to minimise the strain at the commencement of the wind. Dynamometric experiments have shown that when the cage is resting at the bottom of the shaft and is suddenly lifted, the strain on the rope is much greater than that due to the load, especially if there is any slack chain to take up. The device of 1844 developed throughout the intervening years has culminated in many ingenious inventions, that shown in Fig. 6 used at the Mariemont Colliery (Belgium), being typical. To the bridle chains an additional one is added fitted centrally and passing from the rope capel to the centre of the cage. This chain is much shorter than the remaining bridle chains and has attached to it a stirrup a, while the pin b is attached to the cage. Threaded on this pin are alternate discs of sheet iron c, and india-rubber e, kept in place by the nut and lock-nut at the top of the pin b. The india-rubber and sheet iron discs are enclosed in a cylindrical case as a protection from dirt, moisture, etc. At the commencement of the wind, the central chain, being shortest, does all the work; the stirrup a slides on the spindle b, and compresses the india-rubber discs until the central chain lengthens to such an extent that the corner chains come into operation and do their share of work. Volute springs have been used sometimes, but had to be abandoned through unreliability as they often broke and caused mishap. The total weight of this apparatus is only 71 lb.

Another arrangement was to have india-rubber blocks placed beneath the pulley pedestals, but being exposed to the weather, the blocks soon became hard and lost their elasticity. At the Bell End pit pedestals were placed on springs similar to those used in railway wagons (see Fig. 7). The pedestals a worked in guides, b, and had a play of about 2 in. The guides compelled the pulley to travel in a vertical plane and a stop c was provided underneath the spring to prevent it from compressing too much; a cross-bar d was placed over the top to prevent the carriage being sprung out of the guides under abnormal shocks.

There were devices to prevent the rope breaking, but more numerous were the patents taken out and the equipment installed to preserve life in the event of the rope breaking. The first to be mentioned in 1839 was that of J. Hare, who invented a safety cage which was apparently used in Staffordshire. Yates, of Walsall, also designed one in 1841. There is mention in the Mining Journal, Vol. xii, 325, of an arrangement designed in 1842 by Booth, of Manchester, for arresting a cage in the event of the rope breaking; this device functioned by means of a rack which engaged with the guides and was actuated by a lever from a small auxiliary rope.

In 1843, Samuel Parley suggested the idea of raising the cage in a safety cylinder on a piston exactly fitting it, so in the event of the rope breaking, the air below would serve as a cushion to check the rapid descent of the cage. This system is mentioned in the Mining Journal, Vol. xiii, 351. A further suggestion was made during the same year to prevent the destruction of the cage in the event of the rope breaking by attaching a cover to the cage and providing a continuous separate rope. Dodd in 1844 suggested a safety cage provided with a brake which was expected to be grasped by those in the cage should the rope break. Many of the aforementioned safety devices were merely ideas or suggestions, but did indicate, in the first instance, the prevalent lack of confidence in wire ropes, and also a desire to ensure the safety of the men being wound. In general, most of the ideas up to this date were unpractical.

The first workable safety appliance was that designed by E. N. Fourdrinier, of Leek, North Staffs, in 1847, and consisted of iron wedges which were forced between the cage and the guides by means of strong springs, enabling the cage to be suspended in the shaft should the rope break. The first arrangement was installed at Sneyd-Green Colliery in 1848, and by 1850 some 40 pits had the device installed. In many cases the appliance proved satisfactory in practice, but at other times it was not so successful, and due to the objection of the miners the device was gradually discarded.

Other safety cages were developed by Heath in 1848, and by White and Grant in 1850. The cage developed by White and Grant was a simple stirrup frame, with a platform having rails for two tubs side by side. The guides were of timber and the slippers of channel iron. The safety catches consisted of four eccentric discs, keyed on each end of two horizontal shafts carried on bearings on the top of the cage. These catch shafts were turned by the action of the, springs which tended so to rotate them as to close the catches on to the guides, while the pull of the winding rope tended to rotate them in the reverse directions. In the event of the rope breaking the springs forced the serrated edge of the disc on to the guides thereby supporting the cage in the shaft. For a number of years this device had considerable popularity.

Calow in 1862 designed the safety cage shown in Fig. 8. A illustrates the cage guide, B the bridle chains, and E is an eccentric carried by a shaft on which is also keyed a lever C; D is a spring which is made to suspend the weight I, and also to keep the eccentrics clear of the guides so long as the velocity of the descending cage does not approach that of a freely falling body. In the event of the rope breaking the pressure of the weight I on the spring D ceases to be so intense and, therefore, the spring lifts it and sets in motion the eccentric E which grips the falling cage. The apparatus, therefore, does not come into action each time the cage stops and starts. It will be noticed that it is not dependent on its action on any direct attachment to the rope.

About the same time Broadbent invented his safety cage which is illustrated in Fig. 9. The cage guides are represented by A, the bridle chains by B, and CC are levers to which the chains are attached, and which, when the weight is carried, keep the eccentrics EE from coming in contact with the guides A. D is a spring for giving motion to the levers CC and eccentrics EE if the rope breaks. F is a wrought iron plate at the side of the cage to carry the apparatus. G represents the framework of the cage. It will be understood that in the event of the rope breaking the springs forced the eccentrics against the guides and the cage remained suspended in the shaft.

Similar types of safety devices were brought forward by Knowles, J. K. Hampshire and John Whiteland in 1862, and in the same year Bennetts devised a safety device for application to skip winding; Harper also introduced his safety device for use with rope instead of wooden guides in 1869. There were many other devices of this type, several of which are described in Colliery Engineering, page 64 of the February issue, 1942.

The uncertainty of action of these devices when the necessity arose, which might be a considerable time after installation, precluded the possibility of their ever becoming a reliable means of ensuring perfect safety in winding and it was realised even in the middle of the nineteenth century that the best means of ensuring safety and preventing winding accidents, was by means of the daily examination of the ropes and other winding equipment. The soundness of this opinion has been fully endorsed by the experience gained in the intervening years.

(To be continued.)

Drawings and Photographs accompanying the article