Columbia University Libraries Digital Collections: The Real Estate Record

Real estate record and builders' guide: [v. 99, no. 2571: Articles]: June 23, 1917

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REAL ESTATE Hi AND (Copyright, 1917, by The Record and. Guide Co.) NEW YORK, JUNE 23, 1917 SAFETY PRINCIPLES APPLIED TO ELEVATORS Many Accidents Avoidable If Proper Precautions Are Taken—Safety Must Be Combined With Art and Efficiency C" LE\/\TOR accidents, like other in- •'—' diistrial accidents, are largely pre¬ ventable if recognized safety principles arc properly applied to the physical equipment, and if tlie elevator operator is properly instructed in right methods of operation under normal and emer¬ gency conditions. Accidents are the results of hazards, and hazards are faults in men, methods or materials. The elimination of haz¬ ards is the elimination of these faults. Ignorance on the part of an elevator op¬ erator is a hazard to be eliminated by education and instruction. Faulty ma¬ terials in car, shaft or hoisting mechan¬ ism are hazards to be eliminated by proper materials. Unsafe practices and methods of operation are hazards to be eliminated by omission entirely of the function, or if tlie function is nec¬ essary, by the substitution of another inethod that is safer and easier than the old method. These evolutions or transformations in men, methods and materials are ap¬ plications of safety principles, which are now being rapidly standardized. There are, of course, misapplications of prin¬ ciples which have brou.ght forth severe criticism and. in some cases, ridicule; but we must exoect some misapplica¬ tions, on account of the newness of the subject and correct thein when we en¬ counter them. With elevator equip¬ ment, our great safety principle is that each and every niece of that equipment must offer the highest possible degree of safety to all persons who are in any way affected by its presence. The sec¬ ond is that safetv must not be used instead of art and efficiency, but must be combined with art and efficiency in such a way as to be always present and at the same time to gain favor with the artist, the efficiency engineer and the public. But in gaining this favor, the application of the principles must provide protection from physical, men¬ tal and moral accident hazards. Let us assume, therefore, a typical elevator installation of modern type and look for points that might be improved in such a way as to reduce incidental accident hazards without interfering wifh efficiency of operation and at the same time outline the general requirements of elevator equipment, in so far as they re¬ late to mechanical features and physical hazards. Starting with the rnachine, which con¬ sists of sheaves, cables and some mech- anisin for transforming the energy as received to contfollable tension in the cables. All parts of this machine should be designed and constructed to give strength, durability and reliability by embodying ample factors of safety based on the car loaded to capacity, with due consideration for the physical proper¬ ties of material employed and the nature of the loads encountered^. If the ma; chine is overhead, it sliould be sup¬ ported on a strong frame with a con¬ tinuous, level floor surrounding _ all parts that require oiling or adjusting. The roorii containing the machine should be well lighted and ventilated. •Mr. Hansen is the Chairman of the Com¬ mittee on Health and Safety of the National Aesoeiation of Manufacturers. By CARL M. HANSEN* regardless of location. Darkness breeds tilth and interferes with good house¬ keeping. This requirement is too often neglected. This room should be pro¬ vided with an effective lock and kept locked at all times against all unauthor¬ ized persons. If the machine is electrically operated, all switches, panelboards and current carrying parts should be enclosed in grounded metal cases to effectively pre¬ vent the accidental contact of persons with live parts of the equipment. All wiring, of course, should be thoroughly protected in conformity with the best modern electrical practice. Mechanism to Be Enclosed. All revolving parts of the mechanism, especially gears and projecting parts, should be enclosed to prevent acciden¬ tal contact with, or injury to the oilers, and other maintenance men; these en¬ closures may be solid sheet metal or perforated metal, depending on the na¬ ture of the hazard. Wooden guards are apt to increase the fire hazard, espe¬ cially if the elevator is electrically driv¬ en. Generally speaking a metal guard offers superior protection. In the case of a hydraulic machine, provision must be made for renewal and readjustments of valves and proper set¬ ting should be maintained at all times. Plunger and valve glands must be kept tight enough to prevent leakage. Creep- age is a fault so nearly universally com¬ mon to hydraulic elevators to be re¬ garded as an inherent hazard, and must always be considered as an important feature in the total accident hazard. .•\niong the accessories necessary for all types of machines are automatic stops to limit upward and downward motion of the supporting cables and control of the source of power. There should be a reliable governor on all machines to prevent car speeds greater than those for which the car is designed. The iinpact force of a car stopped suddenly increases with the speed. Essential parts are designed to withstand these loads only at the ma.xi¬ mum specified speeds. Cable Requirements. For all passenger and freight cars and counterweights, there should be two or more cables of cast steel or soft iron, preferably of a smaller diameter, that .is }/2-inch to 'i-jnch in diameter. These cables should be fastened in a 1 eliable manner to the cars and counter- wei.ghts. One method which has proved to be reliable employs a conical cast¬ ing through which the cable is passed, the strands separated, turned in and the remaining space filled with solder. Ii" this method is used, the cable must be carefullv "pickled" and cleaned to give the best results. A new set of cables capable of with- standin.g a load 10 times as great as that to which it is subjected when the car is loaded to capacity and operated normally is considered sufficient' fo'r a larse maiority of cases. The minimum diameter of sheave for any cable is given bv reliable manufac¬ turers and these sizes should, in all cases, be adhered to, smaller sheaves often causing rapid deterioration of the cable. In general, the ratio of the diam¬ eter of the sheave to the diameter of the cable should be about 60 to 1. Varia¬ tions therefrom depend on the number and size of strands in the cable and material of which they are made; in other words, on flexibility and elesticity of the cable: The size and shape of grooves for dif¬ ferent cables is a prime factor in the de¬ sign of the sheave; if the cable binds, natural rotation is prevented and in¬ ternal strains are introduced which sometimes result in a broken cable. The grooves do not always retain their original shape under operation. The cable sometimes cuts the groove to a new shape and the groove some¬ times cuts the cable, depending on com¬ parative hardness. Either condition re¬ quires the attention of a trained attend¬ ant, and should, in no case, be allowed to exist until a critical condition appears. External vigilance bv frequent inspec¬ tions, regrooving the sheaves and re¬ moval of cables before they reach a dangerous condition is the price of cable security. There should always be a shaft en¬ closed in fire retarding partitions with doors over all openings that are suitable for stopping persons and fire from pass¬ ing through the opening. The absence" of an enclosed shaft has caused many serious and fatal acci¬ dents. It is common practice in too many places to install freight elevators without a shaft of any kind. Too much cannot be said against this practice. There also are elevator installations where the hatchway openings are par¬ tially enclosed by a fence, and there are hatchways with automatic trapdoors, and still other combinations of protec¬ tive devices which are compromises be¬ tween minimum and maximum protec¬ tion. The shaft has been recognized as a necessity to protect crowds and pre¬ vent catastrophes for a long time, but its restricted use, which is largely con¬ fined to passenger elevators, would in¬ dicate that this measure has been consid¬ ered extravagant where only one or a few persons are exposed to the hazard. No doubt, the hazards of open hatch¬ ways are more serious on passenger elevators than on freight, the hazard be¬ ing proportional to number of users, but nevertheless, they are serious enough in the case of freight elevators in this day of workmen's compensation, and should be eliminated by use of stand¬ ard shafts and doors in all cases. Open hatchways or shafts enclosed bv llaiTimable partitions are a menace in so far as the fire hazard to property is concerned, but an open hatchway is a far more serious hazard to persons than to property, because fire is one of the hazards to life; the same fire that de¬ stroys property may also destroy life, and in addition to fire hazard to per¬ sons, there is the danarer of any occu¬ pant on any floor taking a fatal fall through the floor openings; and there is also the danger of shearing between k;nfiing and car floor. Now with the shaft enclosed in fire- rtsisting walls, there must be a door at each floor. This door, as previously slated, should offer a high resistance to heat transmission and should be eas¬ ily and safely operable. The door RECORD .VND GUIDE IS IN ITS FIFTIETH YE.VH OK CONTINUOUS PUBLICATION.