SHAFT SAFETY

We are proud to display this photograph of an old cage which is exhibited in the People's Palace, Glasgow Green.
All copyright acknowledged.

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TABLE 1 - EXAMPLES OF WINDING ACCIDENTS

From the early 19^th century steam winding engines and wire ropes were rapidly replacing the horse gin and hemp ropes for the winding of men and material in vertical shafts. Legislation was slowly introduced and by 1911 the main aspects of safety covering the carriage of persons and materials through shafts was in place. These are summarised below:

   *Rules for the inspection and maintenance of shafts and winding apparatus.

   *Provision of winding apparatus with brakes and depth indicator.

   *Construction of cages and conveyances.

   *Prohibition of spliced ropes.

   *Prohibition of men and material being wound at the same time.

   *Rules governing the inspection and life of winding ropes.

   *Age, duties and hours of employment of winding enginemen.

   *Duties of banksmen and onsetters.

   *Provision of signalling apparatus and codes of signals.

   *Provision of automatic contrivances to prevent overspeeding and overwinding.

   *Means for detaching the ascending cage in the event of an overwind.

Two main dangers arise in winding, overwinding, i.e., any movement of the cage past normal decking level, and overspeed, which is most dangerous when it occurs near to the end of the wind, owing to the danger of an overwind occurring. This was recognised by the Act of 1911 but, following the shaft incident at Bickershaw Colliery in1935, an Overwind Protection Committee concluded that the greatest danger in an overwind lay in the speed at which the descending cage could strike the 'bearers' at the shaft bottom, with consequent risk of injury to persons by the impact. (The ascending cage has the 'protection' of the detaching hook).
Regulations were introduced in 1937 requiring the automatic contrivance to prevent the descending cage landing at a speed in excess of 5 ft/sec (1.5 m/sec).

OVERSPEED AND OVERWIND CONTRIVANCES.

A popular type of controller is the Lilly Duplex controller shown in Fig.1

Fig.1  LILLY DUPLEX CONTROLLER

Position of cage in the shaft.
Two cam dials, one for each direction of motion, are mounted on hubs, keyed to a common shaft and driven by a spur and worm gearing on a drive from the rotating winding drum. The gear ratio is such that a maximum angular movement of the dials of about 300° corresponds to the travel of the cages or skips in the shaft.

Speed of cage in the shaft.
Two centrifugal governors, driven by a shaft from the winding drum, operate on a floating lever system which is connected to a pair of floating contacts. An increase in speed causes the governors to exert more force on the lever system and the floating contacts come closer together.
An increase in speed of about 10% above normal sounds an alarm and if no action is taken, these contacts close to operate the safety circuit which cuts off power to the winding engine and actuates the braking system.

Combined operation.
The requirements of a braking system are different at various points in the wind. For example, when at maximum speed in mid-shaft, it would not be prudent to apply full braking force because of the shock to the winding system and, if men are being wound, causing injuries due to the rapid deceleration of the cage. Conversely, at the end of the winding cycle when the cage is approaching pit bottom, full and fast braking is essential to prevent overwinding. These and other conditions are catered for by the action of cams bolted on to the dial.
At the point in the wind at which retardation should commence, the retarding cam engages a roller on a pivoted arm which is connected through a rod to the floating lever system. As the cam rotates, the roller is depressed and the floating contacts brought closer together. The cam is so shaped that if the winding engine is retarded at the correct rate, a small clearance is maintained between the contacts. If, however, the speed is not continuously reduced, the contacts will close, first giving a warning to the winding engineman and if the warning is ignored, to actuate the braking system.
Further cams may be added, such as the acceleration cam which allows maximum acceleration of the ascending cage, and limit cams which operate the braking system to prevent overwinding.
When men are being wound, the sensitivity of the system is increased by applying a spring loaded lever to the fulcrum of the floating lever system. Auxiliary contacts are fitted and arranged to close when the controller is thus set for man-riding; and a circuit is completed to illuminate indicators 'MEN' at the pithead to show the setting of the controller as required by legislation. This arrangement is commonly known as the 'slow banker'.

Note.
With modern winding installations the winding rope may be magnetically 'striped' along its length like the bar codes used to identify produce in supermarkets and shops. Electronic sensors relay the speed and position of the cages to a central processor which controls the winding engine and initiates any corrective action. This has led to fully automated, push button winding, with no one in attendance, although Regulations may require a winding engineman to be in attendance when men are being wound.

DETACHING HOOKS

The use of a detaching hook in winding practice is a basic safety provision required by legislation. The intention is to provide a safety device which will come into operation if the other protective devices fail to prevent an overwind and the winding engine fails to stop at the end of a normal wind. In the absence of such a safety device, the ascending cage would be drawn up into the headframe and either, be drawn over the pulley wheels before crashing to ground level, or, if the rope broke due to the collision, falling back down the shaft, each with disastrous consequences.
The device consists of two main parts, an open-ended, bell-shaped circular plate located in the headgear below the pulley wheels and a detaching hook fitted between the rope shackle and the cage suspension gear. See Fig. 2.

The device fulfills two functions in the event of an overwind, first to release the winding rope from the cage and second, to prevent the cage from falling back down the shaft when the rope is released. There are several types of detaching hook in service and the following description shows the general principle and design of the Ormerod Hook.

Fig. 3 shows the principle of operation of the Ormerod detaching hook.

The detaching hook is made from three plates, two outer and one inner (shaded). The plates are pivoted on a central bolt P and held in position by a copper pin C passing through the three plates. Slots are cut in the plates to enclose the pin in shackle A to which the winding rope is attached.
The cage or skip is suspended from shackle B, the pin being passed through a shaped-slot in the lower part of the plates.
If there is an overwind, the hook is drawn up into the bell (position 1) and the narrow throat TT forces the lower parts of the plates together, shearing the copper pin C and opening the slot in the top of the hook to release shackle A (position 2).
The projections L on the plates are also forced outwards and engage with the top of the bell to retain the hook. At the same time the pin in shackle B drops into vertical slot D, securely locking the three plates in position. The cage or skip is then suspended in the bell.

Note.
Detaching hooks must not be fitted in friction winding systems, (where the rope(s) are not wound on the driving drum but only pass over the top part of the driving drum or sheave), as detaching the ascending cage would cause both cages and winding rope(s) to fall down the shaft.
In friction winding systems, protection for the ascending cage in the event of an overwind is provided by a cage 'receiver' fitted with tapering guides to slow down the cage and a 'bumper beam' at the top of the receiver to finally stop the retarded cage. The drum or sheave will then be able to turn against the friction grip of the ropes. If the worst case happens i.e., the rope(s) break then spring loaded catches in the receiver prevent the cage from falling down the shaft.

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"Dunfermline Press"
20 August, 1859

The "MINER'S SAFETY CAGE" - a platform used for raising and lowering men, and likewise coals and ironstone from a shaft or pit - is an invention by Robert Aytoun, Esq., of Capledrae, himself an extensive coal owner, who has bestowed much time and money in bringing the cage to its present satisfactory state.

Like many valuable discoveries, it is of the most simple construction. Those acquainted with mining terms, will understand us when we say, that the upper slides or shoes attached to the cage are so arranged that in the event of the rope or gearing giving way, a simple spring so tilts the slides or shoes that they immediately seize hold of the guide rods in the same manner as a person lays hold of boring rods with a key; and although the rope should come down upon the top of the cage, the effect is that it causes it to dig deeper into the guide rods, and thus becomes the more secure.

The cage may be seen in operation at Lochgelly Iron Works and Donibristle Colliery in this neighbourhood, and we have no hesitation in predicting that ere long it will be in general use. It was seen by thousands of people in the Highland Society's show-yard, where it attracted much attention; many of the miners themselves had an opportunity of seeing it there, and expressed their opinion that Government ought to enforce its adoption. We understand Mr. Aytoun has taken out a patent for this invention, but in order to encourage its general use, the price is almost nominal.

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"Dunfermline Journal"
Saturday 18 August, 1883
SHOCKING CASE OF OVERWINDING AT LITTLE RAITH COLLIERY
THREE MEN KILLED AND FOUR SERIOUSLY INJURED

It is our painful duty today to report the most serious colliery accident in Fifeshire since the fatal boiler explosion at Fordell in 1876, when three people were killed on the spot, and six seriously injured - a fourth case proving fatal a fortnight hence.

The scene of the accident which took place on Wednesday afternoon at three o'clock was the Dora Pit, Little Raith Colliery, belonging to the Lochgelly Iron and Coal Company, and is situated about 500 yards to the south of Cowdenbeath Railway Station. The pit is one of the largest in Fife, and is worked on what is known as the double cage system - that is to say that the cage is so large as to admit a double load either of men or of coal. The winding is performed with a coupled engine fitted with all modern appliances, while all the "gearing" at the colliery is of the very best kind. On Wednesday the winding was in the charge of James Guthrie, who, since his appointment to that post some four months ago, has proved himself a most capable servant. At least 150 men descended the pit shaft in the morning, and everything went without hitch while coals were being brought to the bank. According to the eight hours-a-day principle the drawing of coals was suspended at two o'clock, and the miners began to ascend at the rate of almost a cage every five minutes. All went well until the last cage of men of the day, when a most terrible case of overwinding over the pulleys occurred.

On the fatal cage were - Thomas Adams (51) and his three sons, Thomas (20), James (16), John (14), and David Paterson (32), Robert Hunter (41) and his son, William Hunter (17).

While the "scaffold", as it might be termed, with its living freight of beings was being brought up the shaft, the people at the pit mouth thought that the pulleys were going unusually fast. As the cage approached the surface it was very apparent that something was very seriously wrong, the speed being such as to make grave apprehension for the men's safety. It passed through the "shuts" at the pit mouth at a speed which struck terror into the minds of two or three men who were in the vicinity of the pit shaft. In a second, aid of course being impossible, the cage was whisked over the pulleys and sent crashing into the roof of the engine house - a distance of sixty feet - with terrific violence. The result was that the unfortunate occupants were tossed about in all directions, none however fell into the shaft.

James Adams and his brother, John, were thrown up in the air with tremendous force and came down on a "bing" of rubbish at least 150 feet from the top of the gearing, where the cage was drawn over. On the two lads being picked up, it was found that in the case of James, life was extinct, whereas John showed signs of vitality. David Paterson seemed to have left the cage immediately on it passing over the pulley, for he came down on to the roof of the engine house with terrible force, falling immediately afterwards to the ground. He was at once cared for, but had been little more than removed from the spot where he fell when he expired. Thomas Adams Senior and the young lad, William Hunter, were dragged right into the roof then being taken from their perilous position into a comatose state. Robert and Thomas Adams Junior were found on the top of the pithead, hovering dangerously near the mouth of the shaft, both showing injuries of a somewhat serious nature.

The eye witnesses of the catastrophe were, of course, thrown into quite a panic by the ghastly sight, and for a few minutes they could render little assistance. Happily, however, they soon became alive to their position, and, having removed those who were in danger of coming by other injuries, Dr Stiell, Lochgelly, and his assistant, and the heads of various departments of the colliery were telegraphed for. Meantime the news spread like wildfire throughout the village of Cowdenbeath, and in little more than twenty minutes after the accident hundreds of men and women were on the spot. Among them were the friends of the men who had been overtaken by the accident; and when the names of the victims were communicated to them, the scenes which followed were suggestive of the figure of "Rachael weeping for her children, and refusing to be comforted." With all possible speed, all the men who showed signs of life were removed to their homes, where, in a remarkably brief space of time, they were attended by Dr Stiell and his assistant. Dr Naysmith, Cowdenbeath, was also soon at the ground and kindly offered to assist his professional brethren. On examination, Dr Stiell was able to report on the accident as follows:

James Adams, killed.

David Paterson, killed.

William Hunter, brought home alive, but died about two hours later.

Thomas Adams Senior, very much cut about the face and right foot very badly bruised. Case hopeful.

John Adams, serious internal injuries.

Robert Hunter, very seriously injured internally.

Thomas Adams Junior, only a few bruises about the face. Least injured of all.

Among those who first arrived at the pit were Mr Lansdale, managing partner of the company. Mr Stevenson, the manager and Mr Connell, Burntisland, all of whom were unsparing in their labours to alleviate the suffering of the injured.

But to return to the scene of the accident. The cage was seen to be stuck fast into the roof of the engine house, the place at which has smashed in, being at least 60 feet from the ground. The engine ropes and gearing were all whole, while the indicator showed that the "drum" had taken at least a turn and a half more than bring the cage up to the landing stage. This led people to infer the accident had resulted from overwinding, but this of course will be a matter for the official investigation. Guthrie, the engineman, who will be about twenty five years of age, for hours after the accident was quite beside himself. In the course of the evening, Inspector Hunter of Fife Constabulary, arrived on the ground and after making some little investigation, he apprehended Guthrie and had him conveyed to Kirkcaldy. Up till a late hour people arrived at the pit from the neighbouring villages, thousands having seen the wrecked cage by ten o'clock.

The villages of Cowdenbeath and Lochgelly have been thrown into mourning by the sad calamity, and on Thursday there was little or no work going on at the Raith Colliery, while there was nothing like a full attendance at the Lochgelly and Cowdenbeath pits. Groups of men hung around street corners in all directions - the one topic of conversation being the accident. On enquiries at the relatives, our reporter was informed that Robert Hunter had remained in an unconscious state during the night, and was still in such a condition as to make recovery doubtful. Thomas Adams Senior was out of danger, while his son Thomas was able to get out of bed. In the case of the other son, John, however, matters were different. He had spent a most restless night and it was apparent that his injuries internally were such as to create doubt as to his recovery. On being questioned about the accident, Thomas Adams Senior said, "the cage was signalled from the bottom in the usual manner." He and his companions went away alright, but at such a velocity was the cage wound up that from the "doorheads" - a short distance above the bottom - to the time he was smashed up against the roof of the engine house his memory was all but a "blank". He had worked in the pits upwards of forty years and never before, from the terrible speed, had he had as little time to gather his wits after leaving the bottom. He understood he was (along with the boy Hunter, now dead) taken from the cage on top of the engine house. Thomas Adams, his son, also spoke of the terrible rate he and his comrades had been brought up from the bottom. They had not time to shout to the engineman to halt. From the "mid-shank" to the pulley was the work of an instant, and before they had time to think of anything, they had been dragged over the dangerous brink. At noon, Mr Morrison, the Procurator-Fiscal for the eastern district of Fifeshire, accompanied by Mr Lansdale, the managing partner of the company, arrived at Cowdenbeath. Mr Morrison, after some preliminary work, opened an inquiry into the accident at Braunton's Hotel. The witnesses first called were those who had been cognisant of the accident, and we understand that so many had been cited that the inquiry will probably last until today. In the course of the day, the scene of the accident was visited by Mr Morrison and shortly afterwards the work of removing the wreck was proceeded with. James Guthrie, the engineman, who was in the charge of Inspector Hunter, was conveyed to Cupar, and, having emitted a declaration before the Sheriff Substitute, was committed to prison pending further investigation.

On Friday morning the wreck had been completely removed from the engine house. One cage was in operation by six o'clock, but few of the miners descended the shaft and had only been at work an hour when they returned. Robert Hunter and the boy Adams were at noon reported still to be in a critical state, both having spent a restless night.

Mr Morrison proceeded with his inquiry in the course of the afternoon. Two young women, who were stated to be in the engine house when the accident occurred, were among those examined. A movement has been set up to get a possible subscription for the sufferers. Mr Bolton, Stationmaster, and Mr Innes, President of the Fife and Clackmannan Miners' Association, are meantime at the head of this movement, and from what has transpired there is every chance of the thing meeting with considerable success.