This paper, from The Journal of the Association of Engineering Societies, Volume 11, 1892, describes the Western Cable Railway, a freight hauling line that used a finite cable in a tail-rope configuration. The author, Edward Flad, designed and built the line. Sadly, the illustrations do not appear in either scan of the article that I have found.
[Read January 20, 1892.]
The Western Brewery of St. Louis, more commonly known as Lemp's Brewery, is located at a distance of about 2,000 feet from the tracks of the Iron Mountain Railroad, and at an elevation above the tracks of 95 feet. There is a continuous ascent from the Iron Mountain tracks to the brewery, the steepest grade along Potomac street which connects the two being 7 3/10 per cent.
Formerly all freight, whether supplies for the brewery or beer shipped therefrom, was loaded and unloaded in the lower yard established next to the Iron Mountain tracks, being transferred by means of wagons between the yard and the brewery. The expense, delay, and annoyance incident to the hauling, up and down so steep a grade, of the large amount of freight, which required from thirty-five to forty two-horse wagons, rendered it desirable to adopt some other method, and finally led to the construction of a cable road by means of which the regular freight cars are transferred between the lower yard and an upper yard which was established on a level with the brewery buildings.
The original preliminary plans were made a number of years ago by Col. Henry Flad with the writer as assistant. At that time a wooden construction was proposed for the cable track. In June. 1890, the Western Cable Railway Company entered into contract with Johnson & Flad to furnish detailed plans and specifications and superintend the construction of the road, and Col. Henry Flad was retained as Consulting Engineer. Work was begun immediately upon the plans, contracts for the material were let, and the construction was prosecuted as diligently as possible. The road was completed and put in operation in June, 1891, and since then it has been in constant use.
A hoisting engine, with a drum of a capacity sufficient to hold the whole length of the cable, is placed at the upper end of the incline. The upper end of the cable is fastened to the drum and from there the cable passes underground, in a conduit placed between the rails, to the grip car to which the lower end of the cable is fastened permanently. The conduit is provided with a slot through which the grip plate from tbe car passes.
To take the cars uphill, the grip car is placed at the lower end of the road, (Plate l,)at A., the freight cars are placed in front, B. and C, and the train is started up the hill with the grip car at the lower end of the train. The cars are pushed up to the position D. E., being on a level with the tracks in the upper yard. From this point they are transferred by means of a light locomotive which is employed to do the switching in the upper yard.
In going down hill the train runs by gravity, pulling the rope along. In either case the grip car is at the lower end of the train so that the safety of the train is not dependent upon the couplings. Two loaded or three empty cars are transferred at each trip.
In the lower yard the cars which are to be taken up the hill are placed on the tracks F. These tracks are laid on a grade of 1/10 ft. per 100 feet towards the cable track, so as to facilitate the running of the cars in that direction. It was originally intended to lay the tracks H. with the same grade in the other direction, as these tracks are used for cars that have been brought down from the brewery and are ready for shipment. By so arranging the grades however, the yard would have been rendered less accessible for wagons, so these tracks were laid level instead.
In the upper yard the tracks are all level. The sharpest curve is a 45 degree curve (130.6 ft. radius). This curve occurs in both yards, but more frequently in the upper yard. The outer rail is not elevated on the curves and the gauge is increased only 1/2 inch. All the switching in the lower yard is done by means of horses. One team of horses readily hauls two loaded cars at a time. Two teams are employed to do the switching in the lower yard. In the upper yard, for a considerable time after the road was put in operation, the switching was done by means of horses, but as before stated a light locomotive is now employed for the purpose.
The cable road is built on a straight line with the exception of one curve at the lower end. This is a 35 degree curve (radius 166.3 ft). The profile of the line is shown on Plate I. The lower end has a grade of 2 feet per 100 feet, up to the beginning of the curve. In passing around the curve the grade is increased gradually. At the upper end of the curve the grade is seven and two-tenths per cent, for a distance of about 300 feet. From there it changes to 6.48 per cent, and then to 5.37 per cent, up to Broadway. At Broadway where the line crosses the tracks of the Broadway cable road, the line is level and from there it again changes to a 2.26 per cent, grade up to the upper end of the road.
The movements of the train are controlled entirely by the engineer at the hoisting engine. Electric signals are established between the hoisting engine and the grip car so that the conductor on the grip car can at any time signal to stop, start, or to go up or down. The electric wires for signalling, as well as for the operation of the safety stop device, to be described hereafter, are placed in the center of the steel cable, the ordinary hemp core being replaced by an electric core.
The grip car is provided with attachments which enable the conductor to stop the train at any time while going down hill. It is also arranged so that in case the cable breaks the safety device is applied through the breaking of an electric current passing in one of the wires in the core.
In the yards a 63 lb. steel rail is used. The tracks are all laid on macadam ballast extending to a depth of 9 inches below the cross-tie. Where the roadway is paved, in the upper yard, the rails are laid on longitudinal stringers, granite blocks are used for paving, and sewer inlets are placed in the center of the track. In place of the ordinary groove for the wheel flanges the whole pavement between the rails is depressed, making a neat construction and one that is readily kept clean.
The cable track is formed by 85 lb. steel rails 5 inches high, resting upon cast iron yokes placed 3 1/2 ft. between centers. The slot rail is a Z rail weighing 53 lb. per yard. The conduit is formed of concrete which fills up the space between the yokes and extends to a depth of 10 inches below the bearing of the yoke under the rail. In laying the concrete, wooden forms were used similiar to those used in the ordinary cable road construction. The conduit is 9 inches wide and 20 inches deep, measured from the top of the slot rail. The'concrete is composed of two parts of Portland cement, five parts of river sand and ten parts of broken stone.
The Yokes: -- (Plate II) weigh about 500 lbs. each, and are designed so as to give ample bearing surface for the heavy loads which are carried; the construction being different from the ordinary yokes especially in the large bearing provided directly under the rail. The rail joints are always made at the yokes.
The Vertical Sheaves: -- (Plate II) which are placed generally, at intervals of 3 1/2 ft., are of cast iron with a chilled groove for the rope. The sheave is five inches in diameter and has a steel shaft with bearings of babbitt metal. The sheave moves in a cast iron frame resting on one side on a cross-bar of the man-hole frame, and on the other side in a cast iron wall box. The original sheaves were but three inches wide, but they have all been replaced by sheaves of a width of 7 1/2 inches. The frame and sheave are removed as a whole.
The Horizontal Sheaves: -- (Plate II) placed at the lower end of the line are 34 feet apart. The sheave is of cast iron fourteen inches in diameter and has a four inch face. The shaft is of steel and rests upon a chiiled cast iron button. The bearings are of babbit metal. The frame and sheave are introduced as a whole, and when in position the frame is bolted to flanges provided in the man-hole casting. A sheet iron cover, not shown in the drawing, protects the upper bearing.
In laying the curved track the T rail was first bent cold to the required radius. An attempt was made to bend the slot rail, but in bending the rail cold the cross-section of the rail was altered, so it was decided to bolt the slot rail to the yokes and spring it into position. This method proved successful, the slot rail being prevented by the jaw of the yoke from changing its shape in cross-section any considerable amount.
At the Broadway Crossing the conduit is made deeper to provide for the operation of the Broadway cable road which crosses the line of the Western Cable Railway at this point. The cables of the Broadway line are depressed at the crossing, passing under the cable of the Western Cable Railway. The Broadway gripman drops the rope and the car passes over the crossing by its momentum. On account of the change of grade it was necessary to introduce a depression sheave to keep the cable of the Western Cable Railway sufficiently depressed to allow the grips of the Broadway cars to pass over the cable.
The Depression Sheave A. (Plate II) is placed upon a bell-crank M. pivoted at O. It is operated by means of a lever which is placed in the gate house in which the air pumps which operate the crossing gates are also located. Whenever the car passes the depression sheave, the sheave is raised to the position shown by the dotted line A'. The rope is depressed 8 1/4 inches below its position in the grip plate. In case the attendants fail to raise the sheave at the required time the increased upward stress on the sheave causes the breaking of the pawl which holds the lever, this being made the weak point, and then the sheave rides up on the rope and over the grip plate without further damage. This accident occurred during the early operation of the road, with the results anticipated, causing no more damage then the breaking of the pawl which was quickly repaired.
The drum, 12 ft. diameter, 6 ft. face (Plate V) is connected to the large gear wheel by means of a friction clutch, and has a band friction brake, consisting of a wrought iron band lined with basswood blocks 10" wide and 8" thick, operated both by a hand lever and by a small steam cylinder, which latter is used only in case of emergency. An intermediate gear connects back to the pinion on the engine shaft. The engine has two cylinders 14 inches diameter X 15 inches stroke. The main drum shaft is 10 inches in diameter with bearings 9" X 16". The main gear wheel is 15'-1" in diameter, has a 10" face and 144 teeth with 4 inch pitch. The cylinders have slide valves operated by link motion. One hundred and fifty revolutions of the engine gives a rope speed of five feet per second, which is the ordinary speed of operation of the road.
All of the levers for operating the drum and engine are placed upon an elevated platform from which the operator has a view of the greater part of the line. The hoisting engine rests upon a foundation of brick laid in Portland Cement mortar.
The grip car (Plate III) is fastened permanently to one end of the cable, the other end being fastened to the hoisting drum. The grip plate is of steel 5/8 inch thick, and at its lower end is 9 inches wide. The lower end of the grip plate is forged into a bulb which is bored conically for the insertion of the cable. The electric core passes through the hollow steel wedge, and from there up into the car. The strands of the cable are wedged into the bulb by means of the hollow steel wedge. Before this mode of attachment of the cable was adopted an experiment was made upon a short piece of cable held in the manner described, and it was found that the grip developed the full strength of the cable without showing any signs of weakness, the cable breaking under a tension of 83,000 lbs. One end of the test piece was looped around an eye and spliced, and one of the strands in the splice broke first. If both ends of the test piece had been held in the form of grip described a higher breaking load would probably have been obtained. The cable has six strands of 19 steel wires each and its breaking load as given by the manufacturer, being figured upon the combined ultimate strength of the individual wires is 123,000 lbs. The ultimate strength of the wire used is 190,000 lbs. per sq. in.
The maximum stress to which the cable is subjected in the operation of the road is about 15,000 lbs. not taking into account the increased stress that may occur, due to a sudden application of the load.
The grip plate is hinged to the longitudinal car timbers, so as to allow for lateral motion.
The design of the safety stop device is as follows: --
A trolley (Plate IV) runs under the car on the slot rails and is attached to the car by means of two chains passing over the sheaves S and S' (Plate III). The other ends of the chains are attached to the cross-head C. The piston operates in a cylinder filled with glycerine and water, the cylinder being bolted to the car body. A cast iron rack is riveted to the under side of the slot rail and the trolley carries a rack of forged steel suspended below the slot rail by two straps which pass through the slot. The spring on the trolley tends to throw the trolley rack up into the position shown by the dotted lines, in which position it engages with the rack on the slot rail. A latch is inserted to prevent the spring from coming into action. If for any reason it is desired to stop the train suddenly, while going down hill, the conductor pulls a handle in the car which releases the latch on the trolley and allows the two racks to engage. The trolley then comes to a sudden stop, but the train travels on until the energy in the moving load is taken up in the cylinder, forming a cushion with a total motion of 4' -9".
The piston is provided with four holes through which tapered plug rods pass, and when the piston moves, the valve on the by-pass pipe being closed, the water is forced through these holes in the piston. As the velocity of the piston decreases, the train being brought to a gradual stop, the openings through which the water is forced also decrease in size, being designed so as to give a constant velocity to the water passing through the openings. A constant velocity here, means a constant pressure on the piston tending to retard it, and hence a constant force tending to stop the train.
The parts are so designed that with a load of 180,000 lbs. travelling down a 7 3/10 per cent, grade at the rate of 5 feet per second, the train will be stopped in a distance of 4 feet, with a uniform tension on the chain of about 30,000 lbs.
(Here I skip some calculations that would be of interest to engineers. JT)
Shortly after the completion of the road this safety appliance was tested in the following manner: The grip car with two loaded beer cars weighing in all about 170,000 lbs. were moving down on the 5 87/100 per cent grade at the usual speed (about 5 feet per second) when the latch was pulled and the train came to a stop within the 4 3/4 feet without any perceptible shock and without any damage whatever. They have used the safety appliance five or six times since the road was put in operation thereby preventing serious accidents. At one time the train was moving up the hill when the friction clutch on the drum broke and the train began to back down hill. The engineer at the hoisting engine saw that the drum was reversing rapidly, but was at a loss to know the cause, or what action to take.
The conductor on the grip car realizing that something had happened, pulled the safety device handle and stopped the train, thereby averting what might have proved a fatal accident.
To further provide against accident in case the cable should break, a magnet (Plate IV) operated by an electric current passing through one of the wires in the electric core, is placed in the car. The magnet supports an armature weighing 22 lbs., and in case the current breaks, the armature drops upon a disc at the end of hand rope and pulls the latch of the safety device.
The electric core contains two No. 16 copper wire conductors, each made up of four wires, and one similiar steel wire conductor. Each strand is covered with tape and is thoroughly insulated. The outside diameter of the core is 5/6 inch. There being no precedent for the use of an electric conductor in this manner, the various electric cable manufacturers refused to guarantee the results and much doubt was expressed as to the possibility of making a cable that would answer the purpose. The first cable was made with a core exactly as described above except that the three conductors were single No. 16 copper wires. When placed in operation the electric wires operated only about four days when all three wires broke. A second cable was ordered with the alterations as indicated above and in the meantime the road was operated by means of hand signals from the top of the car and electric signals through an overhead wire between the two ends of the roads.. The new cable was inserted November 8, 1891, and up to date the two copper wires are in good condition. The steel wire broke during the manufacture of the cable.
The upper end of the steel cable being fastened to the drum, the electric core is brought down to the shaft of the drum and passes through a hole drilled longitudinally into the shaft, emerging at the end of the shaft (Plate IV) where the wires are attached to the brass rings which are in contact with brushes, from which latter the wires lead to the bell and batteries.
The number of cars transferred varies greatly. At present they average about forty cars, whereas in summer they transfer from sixty to eighty cars per day. By the terms of the City Ordinance authorizing the construction of the road the company is required, at the request of the owner of any property fronting on said railway, to transfer cars from the main track to such property and vice versa. It is expected that such a service will be developed in the future, and plans have already been submitted by one of the property owners along the line; but so far, such cars as have been transferred for parties other than the brewery have been delivered in the upper yard.
The first day the road was operated an unexpected difficulty occurred. The lower end of the line being built on a comparatively slight grade, and the friction in passing around the curve being considerable, the grip car developed a tendency to stop on the down trip, before reaching the end of the line. It was finally decided to let the car down with sufficient speed so as to obviate the clanger of a stoppage before the car should reach the lower end. This was done forthwith. The car was pulled up on the steep grade and let down with a flourish. The speed kept on increasing at a rate such that some of the men became frightened and jumped off, and others rushed to the brakes and finally stopped the car. No further thought was given to the occurence for the time being, and a coal car was switched in and taken up the hill. The grip car was then lowered again, with a view to making another trip. Before the next trip was made however an inspection of the grip plate disclosed the fact that a serious difficulty had arisen. In attempting to lower the grip car with all possible speed the engineer at the hoisting engine, anxious to give the car all the rope possible, had unknowingly unwound several coils of cable into the pit. This accounted for the uncontrolled speed of the grip car. When the car was finally stopped the cable kept on going and doubled up under the car; and when the cable was again pulled taut, it looped around the grip plate, lying partly below the lower end of the plate. This was not discovered until after the next trip when the grip was inspected, as the cable is all under ground and not visible except through the slot or man-holes. The clearance between the bottom of the grip plate and the vertical sheaves being only about 3/7 inch, and the rope now being doubled up under the grip plate, in going up hill a number of the vertical sheaves were either broken or damaged. The writer was on the car at the time and he remembers feeling a series of thumps at regular intervals. As the street had been newly macadamized he supposed that the commotion was due to stones on the track, but was somewhat surprised at the regularity of the occurrence. Each thump meant another sheave demoralized. To prevent the recurrence of the accident a simple contrivance was designed which notifies the engineer the moment he has any slack rope in the pit. (Plate V). A long board with the ends resting upon springs, is placed across the pit and just below the normal position of the cable. Electric push buttons are placed at either end of the board. The moment the cable becomes slack it rests on the board, and an electric bell rings continuously until the engineer takes up the slack. No further trouble has been experienced since the introduction of the electric tell-tale.
Following is a table giving the cost of the work:
The cost of engineering and superintendence is not included in the above. All the material was purchased by the company through their engineers, who obtained the bids and wrote all of the contracts. The labor was furnished by a local contractor who was allowed 15 per cent, on the cost of the labor. This is included in the estimate given. The engineers had full charge of the work and received as compensation a percentage of the cost of all material and labor used in the work.
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