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Subchapter 6. Elevator Safety Orders
Article 18. Design Data, Formulas, Tests on Approved Devices, and Electrical Regulations

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§3107. Factors of Safety for Suspension Wire Ropes and Design of Wire Rope Fastenings for Power Elevators.


(a) Factors of Safety for Wire Ropes.

 (1) The factor of safety for wire ropes shall be calculated by the following formula: 



                S X N
           f = -------
                  W	 

 Where: 


 S = Manufacturer's rated breaking strength of one rope. 


 N = Number of runs of rope under load (See Note). 


 W = Maximum static load imposed on all car ropes with the car and its rated load at any position in the hoistway. 


 Note: In the case of multiple roping, the number of runs of rope (N) under load will be: For 2:1 roping, twice the number of ropes use; for 3:1 roping, three times the number of ropes used; etc. 


 (2) The factor of safety for wire suspension ropes shall be not less than that determined by Figure 3107 A2 for the various rope speeds. 





Factors of Safety of Suspension Wire Ropes of Power

Passenger and Freight Elevators

FIGURE 3107 A2

(b) Design of Wire Rope Fastenings.

 (1) Tapered babbitted-type rope sockets shall be of a design shown in Figure 3107 B1 as follows: 


 (A) The axial length (L) of the tapered portion of the socket shall be not less than 4 3/4 times the diameter of the rope used. 





Tapered Babbitted Rope Sockets

FIGURE 3107 B1

 Note: Rope socket and shackle rod may be in one piece, as shown 


 (B) The axial length (L ') of the open portion of the rope socket shall be not less than 4 times the diameter of the rope used. 


 (C) The length of the straight bore (L ") at the small end of the socket shall be not more than 1/2 in. (12.7 mm) nor less than 1/8in. (3.2 mm) and its outer edge shall be rounded and free from cutting edges. 


 (D) The diameter (d) of the hole at the large end of the tapered portion of the socket shall be not less than 2 1/4 times nor more than 3 times the diameter of the wire rope used. 


 (E) The diameter (d ') of the hole at the small end of the tapered portion of the socket shall be not more than shown in Table No. 3107 B1E. 


TABLE NO. 3107 B1E

Relation of Rope Diameter to Small Diameter of Socket

 
Nominal Rope Diameter ......... Maximum Diameter of Hole                   
     in........................      d ', in.                              
3/8 to 7/16 inclusive..........  3/22 " larger than Nominal Rope Diameter  
1/2 to 3/4 inclusive...........  1/8 " larger than Nominal Rope Diameter   
7/8 to 1 1/8 inclusive.........  5/32 " larger than Nominal Rope Diameter  
1 1/4 to 1 1/2 inclusive.......  3/16 " larger than Nominal Rope Diameter  
 
 
 
GENERAL NOTE                       
1 in. = 25.4 mm                    
Title 24, Part 7, Section 7-3107.  
 
 
 (2) Types of rope fastenings other than individual tapered babbitted rope sockets may be accepted by the division subject to the following: 


 (A) Data is submitted showing the results of adequate tensile and fatigue tests made by a qualified testing laboratory. 


 (B) The fastenings shall conform to the requirements of Section 3042(j). 


 (C) The rope socketing shall be such as to develop at least 80 percent of the ultimate breaking strength of the strongest rope to be used in such fastenings. 


 (D) U-bolt type rope clips (clamps) shall not be used for such fastenings. 


 (3) Cast or forged steel rope sockets, shackle rods and their connections shall be made of unwelded steel, having an elongation of not less than 20 percent in a length of 2 inches, conforming to ASTM A235 for forged steel, and to USAS G50.1 (ASTM A27) for cast steel, and shall be stress relieved. 


 (4) The shackle rod, eye bolt, or other means used to connect the rope socket to the car or counterweight, shall have a strength at least equal to the rope manufacturer's rated breaking strength of the rope. 


 (5) Eye bolts used as connections with clevis-type sockets shall be of forged steel conforming to ASTM A235 without welds. 


 (6) Rope sockets shall be of such strength that the rope will break before the socket is perceptibly deformed. 


(c) Method of Babbitting Wire Ropes in Tapered Sockets. Where the tapered babbitted type socket is used, the method and procedure to be followed in making up the fastening shall conform to the following:

 (1) Handling: The rope to be socketed shall be carefully handled to prevent twisting, untwisting, or kinking. 


 (2) Seizing of Rope Ends: The rope ends to be socketed shall be served before cutting with seizings in accordance with the following: 


 (A) The seizing shall be done with annealed iron wire, provided that other methods of seizing may be used which give the same protection from loss of rope lay. 


 Where iron wire is used for seizing, the length of each seizing shall be not less than the diameter of the rope. 


 (B) For nonpreformed rope, three seizings shall be made at each side of the cut in the rope. 


 (C) For preformed rope, one seizing shall be made at each side of the cut in the rope. 


 (D) For nonpreformed rope, the first seizing shall be close to the cut end of the rope and the second seizing shall be spaced back from the first the length of the end of the rope to be turned in. The third seizing shall be at a distance from the second equal to the length of the tapered portion of the socket. 


 For preformed rope, the seizing shall be at a distance from the end of the rope equal to the length of the tapered portion of the socket plus the length of the portion of the rope to be turned in. 


 (3) Spreading of Rope Strands: After the rope has been seized, it shall be inserted into the socket through the hole in the small end a sufficient distance for manipulation; and where nonpreformed rope is used, the first two seizings shall be removed. The rope strands shall then be spread apart and where rope with fiber core is used, the fiber core shall be cut away as close as possible to the remaining seizing. 


 (4) Removal of Grease or Oil: Grease and oil shall be removed by cleaning the outer surface of the exposed rope strands with a nonflammable low-toxic solvent. 


 (5) Turning in of Rope Strands: The exposed rope strands shall then be bent, turned in, and bunched closely together, each strand being turned back the same distance. The portion turned in shall have a length of not less than 2 1/2 times the diameter of the rope and such that, when the rope is pulled as far as possible into socket, the bend of the turned-in strands shall be slightly overflush with the mouth of the tapered socket (large end) and will be visible when the socket has been babbitted. Where rope with steel core is used, the steel core shall be cut off even with tops of the looped strands. 


 (6) Insertion of Bent-In Rope Strands in Socket: The rope end shall be pulled as far as possible into the socket so that the remaining seizing projects outside the hole at the small end of the socket. 


 (7) Position of Socket Preparatory to Pouring Babbitt: The socket shall be held in a vertical position with the large end up, and the rope held in a position truly axial with the socket. Tape or waste may be wound around the rope at the small end of the socket to prevent the babbitt from seeping through, but shall be removed after the metal has cooled. 


 (8) Heating of Babbitt: The babbitt shall be heated to a fluidity just sufficient to char a piece of soft wood such as white pine without igniting it. Care shall be taken not to overheat the babbitt sufficiently to damage the rope. 


 (9) Heating of Socket-Basket and Pouring of Babbitt: The rope socket-basket shall be heated by a blowtorch flame sufficiently to prevent chilling of the babbitt and to insure that the babbitt when poured will completely fill the basket, including all the spaces between the rope strands. Following this the molten babbitt shall be poured slowly and evenly into the basket until it is filled to a point level with the top of the opening in the large end. 


 (10) Babbitt metal shall contain at least 9 percent antimony and shall be clean and free from dross. 


(d) Design of Suspension Rope Equalizers. Cable equalizers and their fastenings may be of types other than individual compression spring type provided:

 (1) Data is submitted to the division showing that adequate tensile and fatigue tests have been made by a qualified testing laboratory. 


 (2) The tests show the ultimate strength of the equalizer and its fastenings in its several parts and assembly, which shall be not less than 10 percent in excess of the required strength of the suspension ropes. 


 (3) Equalizers of the single-bar type or springs in tension shall not be used. 


<General Materials (GM) - References, Annotations, or Tables>


    Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.  


 HISTORY 
   
1. Amendment of subsection (b) filed 6-11-86; effective thirtieth day
thereafter (Register 86, No. 24).

2. Editorial corrections (Register 95, No. 34).

3. Change without regulatory effect amending subsection (b)(1)(A) to provide
more legible illustration in Figure 3107 B1 filed 5-1-2009 pursuant to 
section 100, title 1, California Code of Regulations (Register 2009, No.
18).

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