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November 1911 |
American Engineer and Railroad Journal |
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600 Ton Reinforced Concrete Coaling Station
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| A new reinforced concrete coaling station having a storage capacity of 600 tons and a hoisting capacity of not less than 125 tons per hour, has been designed and built by the
Roberts and Schaefer
Company, Chicago, for the Baltimore and Ohio R. R.
Co., at Sir Johns Run, W. Va. There are two 2½ ton
Holmen balanced hoisting buckets working in unison and traveling vertically from the bottom of bucket pit to the top of the hoisting tower and discharging automatically onto the chutes under the pocket. The pocket is arranged to deliver coal to locomotives on four tracks-two under and one on each side of pocket. The general layout of the station is illustrated on accompanying
illustrations. The receiving hopper is 20 ft. long and 15 ft. wide and built of plain concrete with well rounded valleys and corners, the surface being finished with 2 in. cement. The track stringers are 24 in. Bethlehem section connected with 15 in. channel separators and the rails are secured to the girders with special clips. In front of the receiving hopper are openings arranged with Barrett self-operating revolving feeders to control the flow of coal and measure the quantity delivered to the Holmen buckets, thereby preventing waste of coal in the bucket pit. The base of rails of receiving track is 3 ft. 6 in. above that of coaling tracks. Plain concrete mixed in proportion of 1:3:5 is also used for the bucket pit, which is 6 ft. wide and as long as the receiving hopper. The pit and the hopper are waterproofed on all sides up to 12 in. from the receiving track. Under the pocket the main coaling tracks are 13 ft apart while the outer tracks are 17 ft from them on each side, in the center of which space rise the 2 ½ ft. concrete collision walls. The latter are 8 ft high above the coaling tracks and go down into the ground 3 ft. Aside from the top and bottom there is no other reinforcement in walls. On the collision walls are erected the overhead coal pocket of 600 tons capacity. The pocket is 32 ft. wide across the tracks and 42 ft. in the other direction and reaches a height of 47 ft. above the base of rails. The headroom under it is 21 ft. 6 in. while the clearance on each side of tracks is 7 ft 3 in. There are four sets of undercut gates with heavy steel counterbalanced hooded aprons, one for each track, so arranged by counter hoppering that all coal in the pocket will be available with a minimum loss of space. The pocket is supported by seven columns in each collision wall, the five inside ones being 16 in. x 24 in. and the two outside ones 12 in. 24 in. The columns are reinforced with 1¼ in. rods, stiffened with occasional use of hoops made of 3/8 in rods and designed to withstand not only the weight of coal and concrete, but to resist 40 lbs. wind pressure on the upper structure. The floor or bottom of pocket slope on an angle of 40 degrees from the center to the walls over the columns and is built in one continuous slab from end to end, which is then counter-hoppered toward the openings. The slabs are 9 in. thick including 1 in. sidewalk finish, reinforced with 5/8 in. rods, the end of which are bent up to resist negative moment at the supports. Additional rods are also provided to take care of shrinkage and temperature strain. Under the concrete slabs and between each two opposite columns is spanned a simple triangular truss with a hanger in the center and apex at the intersection of the sloping floors. On account of the enormous tensile stress coming on the bottom chord of the truss, the method of securing the ends of the rods to the columns becomes an important factor. Also the fact that the intersection of the neutral axis of the top chord with the centerline of the bottom chord is about 2 ft. away from the center of the column, multiplied the difficulties in reinforcing the ends of trusses. Great care was exercised in erecting the trusses to have the rods in the bottom chords tightly stretched before the concrete was placed in order to prevent cracks in the beams and possible deformation of the trusses. The too chords are designed for both direct compression and flexure, the section being assumed as T-beams, as the floor slab undoubtedly comes into play to resist the combined stress above the neutral axis. The shear is taken up by bent up rods and closely spaced stirrups, as well as by the concrete itself. The walls are divided into panels by means of pilasters, one over each column and at the center of walls across the tracks. The former walls are 6 in. thick and the latter 10. in, both straight for the entire height, but the amount of reinforcing varies with the depth of walls. The pilasters are in turn tied to those opposite with beams across the inside of the pocket. A provision is also made here to take care of the negative moment, temperature and shrinkage strain. As the work on the pocket was to be done without interfering with the traffic on the main tracks, it necessitated constructing an overhead temporary structure to support the trusses, floors and a part of the walls and the forms. In order to accomplish this, 9 20-in. I-beams were swung across the tracks just below the bottom chords of trusses, leaving a clearance of 19 ft. above the rails. Concrete mixed in proportion of 1:2:4, the stones small enough to pass a ¾ in. ring, was used in the construction of the pocket, while the concrete for the collision walls is 1:3:5 mixture same as the other part of the foundation. As is shown in the illustration, the hoisting tower is 7 ft 6 in. but 18 ft. 8 in. in plan and 80 ft height above the receiving track. It is built with substantial structural section, cross braced on four sides as well as on the inside bents and rigid enough to withstand the strain from live load due to the traveling buckets and 40 lbs. wind pressure on the exposed surfaces. The canopy over the pocket and the bridge from the tower are also steel framed and covered like the upper portion of tower, with American Ingot Iron on the walls and Carey’s Magnesia Composite on the roofs laid on 1 in roof boards. The hoist house is located next to the bucket tower even and level with the top of receive hopper. It is built with reinforced concrete throughout and equipped with 20 h.p. Ohio gasoline engine with Roberts and Schaefer Co’s standard reversible hoist, a cooling water tank and service stop to prevent over winding of buckets. After a short experience with the coaling station, the B. & O. R. R. Co. awarded a contract to Roberts and Schaefer Co. for three duplicates, which are now under construction at La Paz Junction, Ind, Warwich Ohio, and Rowlesburg, W. Va. Description prepared by H. S. Shimizu designing engineer, Roberts & Schaefer Co. Illustrations: Cross Section - American Engineer and Railroad Journal - 43K General Ground Plan - American Engineer and Railroad Journal - 36K West Side of Coal and Water Facility - BORRHS Photo - 78K East Side Closeup of Coal and Water Facility - BORRHS Photo - 11K *A. R. Holmen Elevating and Conveying Mechanism - United States Patent and Trademark Office - Patent Number: 00865041 *A. R. Holmen Loading and Unloading Apparatus - United States Patent and Trademark Office - Patent Number: 00854890 If Patent does not load: Click "Full Text" then click "Images" *Requires TIFF plug-in |
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