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Workmanship.

Linings.

812. Bearings shall be bored for the journal and finished smooth after the lining has been put in. The bearing shall be bored 1/50 inch larger than the diameter of the journal. Bearings for rack pinion shafts shall be bolted to the bracket supporting them and bored while so fastened to insure perfect alinement. The edges of oil grooves and the edges of linings shall be rounded.

Bronze linings shall be turned on the outside to fit the bored hole in the bearing.

Babbitt metal shall be poured in the bearings in such a way that the thickness of the lining after boring will be uniform.

Bearings.

813. The rubbing and bearing surfaces and the joints between cap and base of bearings shall be finished. The holes in cap and base shall be drilled. The holes in bearings for bolts fastening them to their supports shall be drilled inch larger than the bolts. The holes in the supports shall be reamed to fit after the bearings have been adjusted. Gear Teeth.

814. The teeth of gears transmitting power for the operation of the bridge, bevel gears, and wheels in the gearing of any motor, shall be machine cut. The periphery and ends of teeth of gears shall be turned. The pitch circle shall be scribed on the teeth.

Bevel Gears.

815. The teeth of bevel gears shall be cut by a planer having a rectilinear motion in lines through the apex of the cone. Rotating milling cutters shall not be used for making bevel gears.

Machine Molding.

816. Uncut teeth shall be machine molded.

Worms and Worm Wheels.

817. Threads on worms shall be machine cut and the teeth of worm wheels shall fit the worm accurately with surface or line contact.

Keys and Keyways.

818. Keys shall be planed and keyways machine cut. The finish of the keys and keyways shall be such as to give the key a driving fit on the sides. Tapered keys shall bear on the top, bottom and sides; parallel faced keys on the sides only.

Castings.

819. Castings shall be cleaned and all fins and other irregularities removed so that they will have clean, smooth surfaces, suitable for this class of work. Castings which are to be attached to structural steel or other castings shall have their contact surfaces finished. Unfinished edges of bases, ribs and similar parts, shall be neatly cast with rounded corners. Inside angles shall have proper fillets. Bosses shall be finished to the correct plane.

Workmanship-Erection.

Bolt Holes and Turned Bolts.

820. Holes for unfinished bolts shall be drilled or reamed not more than inch larger in diameter than the bolt. The diameter of the shank of turned bolts shall be at least inch larger than the diameter of the threaded portion. The bolt shall be 1/64 inch smaller in diameter than the bolt hole.

Assembling Machinery.

821. If practicable, machinery parts shall be assembled on the supporting members in the shop. They shall be aligned and fitted, and holes in the supports shall be drilled with the members in correct relative position. The members shall be match-marked both to the supports and to each other, and re-erected in the same relative positions. If assembling is not practicable, the holes in the supports shall be left blank and drilled in the field after the machinery parts are assembled and aligned.

Sheaves.

822. The grooves in sheaves shall be turned. The shape of the grooves shall conform as closely as feasible to the rope section so that while the ropes shall run freely in the grooves, the sides of the grooves shall prevent the wire ropes from flattening under static loads, as when supporting counterweights, Built sheaves shall be assembled and permanently riveted before the grooves are turned.

Grooves in Trunnions.

823. The grooves in the surfaces of trunnions and similar large bearings shall be machine cut. Small inequalities may be removed by chipping and filing. The grooves shall be smooth, especially the rounded corners. Holes for Sheaves for Vertical Lift Bridges.

824. In vertical lift bridges, the holes in the girders and columns for the bolts connecting the main sheave bearings to their supporting girders, shall be drilled from the solid through cast iron or steel templates on which the bearings were set and accurately aligned when the holes in the bearings were bored. The bolt holes and the bolts shall be turned to the same diameter and the bolts driven to place without injury to them, the bearings, the girders, or the columns.

Air Buffers.

825. The workmanship on air buffers shall be so accurate that the weight of the cylinder and its attachments will be sustained by the confined air for six minutes, with a piston travel not more than that which occurs during the closure of the bridge. The valves must be closed and the buffers balanced so that the whole weight is carried by the piston rod.

(9) ERECTION

901. The General Specifications for the Erection of Steel Railway Bridges of the American Railway Engineering Association shall apply to the erection of movable bridges, with additions specified herein.

Erection.

Protection of Parts.

902. Parts which are protected from the weather in the finished structure shall be protected in the field during erection by housing or equivalent means. This applies in particular to electrical parts.

903. Rubbing surfaces of trunnions and machinery bearings shall be protected by metal thimbles packed with oil-soaked waste.

904. Wire ropes shall be housed and stored at least 18 inches above the ground. The ropes shall be kept free from dirt, cinders, and sand. During erection, the ropes shall not be pulled through dirt, or bent into sharp angles or kinks.

Lubrication.

905. The counterweight ropes and the operating ropes shall be given two coats of dressing, with an interval of one month between the coats. The dressing shall not be applied in an atmospheric temperature below 40 degrees F. The Contractor, during erection, in particular just before the final test, shall lubricate the sliding parts and fill all grease cups.

Channel Lights.

906. During erection and in taking down the old span, the Contractor shall place and maintain navigation lights and signals, in accordance with the government requirements, for the protection of the falsework, as well as navigation.

Erection of Machinery.

907. The machinery shall be erected by men skilled in the work. Special care shall be given to the alinement of trunnion bearings.

Testing of Machinery.

908. Before the main operating machinery is connected for transmitting power, it shall be given an idle run of 8 hours.

909. The end lifting devices shall be adjusted to produce a lift equal to the deflection caused by the negative end reaction of the live load and impact plus 25 per cent. of their sum.

910. The Contractor shall adjust the counterweight so that the span will be properly balanced.

Bridge Operator.

911. For a power operated bridge, the Contractor shall provide at his own expense, a competent man to supervise the operation of the bridge for a period of 30 days after acceptance. The man shall instruct the employees of the Company in the operation of the bridge.

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