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"The advantage of the wire rope system for hoisting the slate blocks and waste out of the quarry was clear to most quarry operators and in just a few years almost every quarry was equipped with this inclined cableway system."
"The advantage of the wire rope system for hoisting the slate blocks and waste out of the quarry was clear to most quarry operators and in just a few years almost every quarry was equipped with this inclined cableway system."
The most common method of extracting mill blocks from slate quarries throughout the world was with guy derricks, also known as a chain and boom derrick. Although they served the purpose well, these derricks had a limited range based on the maximum extent of the boom, leaving quarries needing to either install a large number of derricks or limit the overall size of their hole. In the Slate Belt district of Pennsylvania though a more revolutionary approach was taken for extracting the stone. Originally conceived around 1870 by a member of the Chapman family of Chapman's Quarries, this system, used almost exclusively in the Slate Belt district for quarrying, was known as the incline cableway which offered a much greater range within a quarry. In fact with multiple cableways established over a single quarry, very little of the quarry was unreachable and the dimension of the quarry was limited only by the strength of the horizontal cables.
The Hoist House
The Hoist House
The hoist house was not unique to the incline cableway system, being necessary for the more traditional derrick system of lifting, but it was still vital to its function. Hoist houses used with this system had a distinctive shape with an elevated clerestory front which provided a way for the cables to reach the top of the headframe.
The hoist house was set a considerable distance back from the edge of the quarry and housed the hoisting engine and the hoist operator or "engineer". Due to the distance from the hole, it was impossible for the engineer to see into the hole itself requiring the engineer to depend on a communication system that combined the "motion boy" or signal man located on the edge of the pit, and the quarry foreman located at the bottom of the quarry. The engines used for an incline cableway were often friction motors manufactured by the S. Flory Manufacturing Company located in Bangor, and known world wide.
The Head Frame
The Head Frame
The head frame of the system functioned as the main supporting member for the cables. The height the head frame provided is what allowed the cable to incline being attached at grade on the other side. The most important purpose of this elevation was not to produce a sloped cable as the name implies, but was to provide a means of bringing the quarried stone up to a height where it could be easily loaded onto small rail cars or carts directly from the carriage. From the hoist shed located approximately 50 feet behind the head frame, cables were attached to the engine. The carriage which ran along the incline cable depended on more than one cable in order to operate. The most significant cable was the stationary cable which extended over the top of the headframe and was anchored firmly to grade both behind the hoist house as well as on the other side of the quarry. The head frame had multiple sheaves located at the top for each of the cables.
This unique method of lifting the slate from the quarry was almost exclusively unique to the slate belt district of Pennsylvania.
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The Carriage and Cable System
The Carriage and Cable System
For large pits three to six cableways were commonly required in order to serve properly all parts of the excavation. Multiple trolleys that allowed the loose "drawing" cable to drape in sections from the stationary cable were used. Attached to the drawing cable was a carriage and from this a "fall block" was added. This pulley , when used in conjunction with a cable increased the lifting capacity of the system. From the end of the block a chain was suspended which was directly attached to the large blocks of slate, or, when men or waste pieces were to be hauled, was fastened to a flat box. The carriage which traveled on the cable was very simple but unique in design combining strength and durability with a ten ton working capacity. The drawing rope used was 3/4 inch in diameter and could be in excess of 1,700 feet long.
For one operation a Flory 10 X 12 double cylinder, double friction drum, and link motion combined hoisting engine was used which gave a working capacity of 400 tons of stone per day delivered every two or three minutes. The drums on these engines were of large size and could hold about 700 feet of drawing rope per minute. The utility of the carriage and cable system of hoisting was generally considered by operators to be the most economical mode for conveying stone to crushers or other material across ravines and places for deposit.
For stripping or uncovering new openings and enlarging mines already partly developed, the facility with which the work was accomplished with the cable system more than compensated for the large expense required to execute the work.
The Motion Shanty
The Motion Shanty
A "motion boy" watched operations very carefully from the motion shanty at the upper edge of the pit far out in front of the hoist house. It was placed in such a way that the person inside had a full view of the entire pit, or at least his one section as defined by the range of that specific incline cableway. Once a block has been separated from the quarry walls, the motion boy would contact the engineer in the hoist house.
The need for slackening the cable, taking up slack, hoisting, or holding steady was conveyed to the motion boy, through arm motion from the quarry foreman in the pit who had charge of work on the quarry floor. The motion boy would then notify the hoist engineer by pushing a button or calling on a phone attached to a cable that ran back to the hoist house. In some very deep quarries where line of sight might be difficult, signals were sometimes transmitted from the quarry floor to the motion shanty by striking a saw blade with a hammer as if using a bell.
A motion shanty located at the side of a quarry for signalling the hoist operator.
Click the arrow in the center of the view to open an interactive 3-D representation. CLICK HERE to open the view in full screen mode (when the window opens click on the arrow in the center of the view).
The Quarry
The Quarry
The incline cableway was fixed across the full width of the quarry but could be moved to a new location as the work in the quarry moved to new locations. The process took time though and was therefore not a common event. Although usually fastened to a concrete footing, there is some documentation suggesting that these cable ways were at times attached to buried logs.
In hoisting out blocks of slate, both care and skill were required to make proper attachment of the chain sling. The rock had to be properly balanced in the chain, and when free of the floor it must be steadied to prevent the cable swinging or twisting before the rock was hoisted.
Great care was taken in hoisting, and close cooperation between the men in the hole, the '' motion boy'', and the hoist engineer was required.
Image Source: Pennsylvania Geological Survey
Hoisting slate. Bangor, Pa. 1923
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