scope:

This code applies to the construction, installation, inspection, main.tenance, and operation of cranes and derricks driven by steam engines, electric motors, or internal-combustion engines; to their runways; to simple drum hoists of whatever motive power; to overhead electric hoists and their runways; to overhead air hoists; and to hand-powered derricks.

This code does not apply to any hoisting machine having maximum capacity of not more than one. ton or to railway or automobile wrecking cranes, skip hoists, hand-operated chain hoists, hoist-like units used for horizon tal pulling only, mine hoists, conveyors, shovels and drag-line excavators, nor to locomotive or crawler cranes having a lifting capacity exceeding 120,000 lb at 12-ft radius or equivalent moment.

This code does not apply to temporary use of cranes, derricks, and hoists on construction work.

The sectional committee fully realizes the importance of proper factors of safety, safe minimum or maximum sizes and other limiting dimensions of wire ropes and their fastenings, sheaves, drums, and similar equipment covered by the code, all of which are closely connected with safety. These features have been omitted because it was practically impossible to include them in a general code covering so many types of equipment and usage, because safe sizes, strengths, and similar things are dependent on so many different factors, often varying with the installation and use. These factors depend on the condition of the equipment or material; on the loads; on the acceleration, deceleration, or speed of the ropes, sheaves, or drums; on the type of attachments; on the number, size, and arrangements of sheaves, and other parts; on weather, and other atmospheric conditions tending toward corrosion, or wear; and on so many variable factors that must be considered in each individual case, that no fixed sizes, dimensions, or strengths could be determined with any degree of unanimity. The advantage of large diameter drums and sheaves, ample factors of safety for wire ropes and all other parts of equipment, and the avoidance of unsafe arrangements were all appreciated by the members of the committee, but it was deemed impracticable to cover them satisfactorily by rules at this time.

The regulation of transient construction cranes has presented different conditions from other industries and has been left to be covered by a general code for that industry, which is now in the course of preparation.

The sectional committee will be glad to receive criticisms of the code requirements and suggestions for its improvement, especially such as are based on actual experience in the applir. ation of the rules. Revised editions will be issued from time to time with such changes as experience in its application and improvements in the arts may dictate.