Suspension Ropes IMechE CPD Certificate Course 23 Nov. 2016 Suspension Rope Standard Configuration Replacement Criteria Tension Measurement Traction Measurement
Standard Nominal diameter at least 8mm BS302 : Part 1 and Part 4 or ISO4344 or other relevant international standards EN 12385-5 (Stranded Ropes for Lifts) 1570 N/MM 2 or 1770 N/MM 2 for single tensile 1370 N/MM 2 for the outer wires and 1770 N/MM 2 for inner wires of ropes of dual tensile 3 BS302 BS302: Part 1 Stranded steel wire ropes Part. Specification for general requirements BS302 : Part 4 Stranded steel wire ropes Part 4. Specification for ropes for lifts BSEN 12385-5:2002 (it supersedes BS302-4: 1987) 4
EN 12385-5 Ropes Grade Rope grade addresses the nominal tensile strength grades of the outer and inner wires. Additionally, the rope grade defines the minimum breaking force of this rope 1570 grade 1370/1770 grade 5 Strand: 6 or 8 Configuration Core: Two types of cores are used: A. Fibre Core (Natural or Synthetic) B. Steel Wire Core i.e. independent wire rope core (IWRC) 6
Symbols for strand construction S strand construction Seale W strand construction Warrington F strand construction Filler or Filler Wire WS strand construction Warrington- Seale 7 SEALE Formation 1 2 9 1 9 2 3 8 8 7 1 4 3 4 7 6 6 5 5 8
FILLER Formation 9 WARRINGTON Formation 10
Symbols for rope core FC Fibre core: a) NFC Natural Fibre Core b) SFC Synthetic Fibre Core IWRC Steel Core (Independent Wire Rope Core) 11 Symbols for wire finish and type of lay U bright (from uncoated) B galvanized sz right hand ordinary lay zs left hand ordinary lay zz right hand lang lay ss left hand lang lay Remark: S Clockwise Direction [LH] Z Anticlockwise Direction [RH] 12
Ordinary lay (sz) Anticlockwise (strand direction - Z RH) Clockwise (wire in the strand s LH) 13 Ordinary lay Right hand ordinary lay Left hand ordinary lay 14
Lang Lay (zz) Anticlockwise (strand direction - Z RH) Anticlockwise (wire in the strand z RH) 15 Lang Lay Right hand lang lay Left hand lang lay 16
Lay Length of Lay Each strands in a wire rope is helical in shape. The distance measured parallel to the axis or the centre line of a rope in which the strand makes one complete spiral around the rope is the length of rope lay. 17 13 8 x 19 S NFC 1370/1770 U sz 13: 13 mm nominal rope diameter 8: 8 strands 19: 19 wire per strand S: Strand construction Seale NFC: Natural Fibre Core 1370/1770: Dual Tensile Outer wires: 1370N/mm2 Inner wires: 1770N/mm2 U: Wire finish: Bright (uncoated) sz(lay): ordinary lay right hand 18
Nominal Tensile strength grade of wires Nominal tensile strength grade in Germany is usually 1570 USA, Japan and many European countries know and use elevator ropes of dual tensile rope grade To come along with sheaves of often minor quality, the outer wires are then of lower tensile strength grade Ropes for roped hydraulic elevators are preferably supplied with rope grade 1770 19 BS6570 (The selection, care and maintenance of steel wire ropes) 90% of the nominal diameter in the case of six and eight strand ropes; Corrosion and chemical attack 20
BS6570 The selection, care and maintenance of steel wire ropes Generally distributed broken wires: six and eight strand ropes in metal sheaves Number of wires In outer strands Rope construction (typical) Number of visible broken wires necessitating discard in a wire ropes fitted to an appliance having metal sheaves when measured over a length of 10 x diameter Factory of safety < 5 Factory of safety > 5 From 101 to 120 6 x 19 (12/6/1) 6 x 19S (9/9/1) 5 10 From 141 to 160 6 x 19F (12/6+6F/1) 6 x 25TS(12/12/ ) 8 x 19S(9/9/1) 7 7 7 14 14 14 21 Discard Criteria (PFEIFER DRAKO) Rope Construction Number of wires in outer strands Number of wires within a length of 6 x Ø Number of wires within a length of 30 x Ø 6 x 19 S - FC = 114 wires 6 12 6 x 19 W FC 6 x 25 F - FC = 114 wires 10 19 8 x 19 S - FC = 152 wires 10 19 8 x 19w FC 8 x 25F - FC =152 wires 13 26 22
Notes If wire fracture don t occur in regular pattern across the majority of the strands but are concentrated in one or two strands, the above table is not applicable Such ropes must be replaced, if there are 5 or more broken wires adjacent to each other within one strand Ropes with excessive crown wear tend to show rapidly increasing numbers of broken wires 23 Measurement of wire ropes Right Way: Set the machinist's caliper to read the widest diameter. Wrong Way: This is the wrong way to measure wire rope diameter. Widest diameter is not being read. 24
Trade Practice Wires A (Even Distribution on each of strands) B (Focus on one Strand) 6 x 19 24 8 8 x 19 32 10 25 Trade practice Reduction in diameter If the diameter of suspension rope is smaller than the following figures, the rope shall be arranged to replace: Rope diameter(mm) 12 14 16 18 20 Max. allowable diameter(mm) 11.2 13.2 14.8 16.8 18.4 93.3 94.3 92.5 93.3 92 90% diameter (mm) 10.8 12.6 14.4 16.2 18 26
Trade practice Types Criteria of Replacement 米仔 Crown wear(mm) 10 12 14 16 18 20 一 8 x (S) 19 3.6 4.2 4.7 5.6 6.3 7.1 6 x (W) 19 4.0 4.8 5.6 6.3 7.2 8.1 8 x (F) x 25 3.35 4.05 4.40 5.38 6.18 6.5 27 British Standard(Health and Safety Executive Guidance Note PM7) No. of broken wires per lay Allowable number Reporting and arrangement for replacement Replacement immediately Type 6 x 19 8 x 19 6 x 19 8 x 19 6 x 19 8 x 19 No. of broken wires randomly distributed among the outer strands < 12 < 15 12 15 24 32 No. of broken wires concentrating in one or two outer strands < 6 < 8 6 8 8 10 28
Code of Practice for Lift Works and Escalator Works Rope Conditions 6-strand x 19 rope 6-strand x 25 rope Rope Replacement Criteria 8- or 9- strand x 19 rope 8- or 9-strand x 25 rope Reduction in diameter 10% 10% No of broken wires randomly distributed among 32 per rope lay 24 per rope lay the outer strands No. broken wires randomly distributed among the outer strands when severe rusting or extensive rouging of the rope is observed No. of broken wire concerning in one or two outer strands No. of broken wires concerning in one or two outer strands when severe rusting or extensive rouging of the rope is observed No. of adjacent broken wires in one outer strand No. of adjacent broken wires in one outer strand when severe rusting or extensive rouging of the rope is observed 12 per rope lay 12 per rope lay 6 per rope lay 4 and the no. of broken wires per lay 12 2 and the no. of broken wires per rope lay 6 16 per rope lay 16 per rope lay 8 per rope lay 4 and the no. of broken wires per rope lay 16 2 and the no. of broken wires per rope lay 8 Tension Measurement What problems of suspension ropes are unequal: A. Traction strength B. Traction Sheave C. Suspension Ropes 30
How to measurement the tension By equipment By hand By calculation 31 By Equipment
By Equipment By Equipment
By Calculation Method 1. Go into the car top and stop the car at the lowest floor (if the travelling is over 40M, the car shall be stopped at mid floor); 2. Use the plastic hammer hit the rope at the point 1M height from the termination; 3. The time shall be measured 5 nos. of completed oscillation; 4. Following the procedures of (2) & (3) for each of ropes and record all the data; 35 By Calculation Method 5) Select the max and min. time and calculate by the formula 6) If the calculation figure is greater than on 0.2, the tension of the ropes shall be adjusted. 36
Lift Traction Inspection Traction Formula T 1 /T 2 x C 1 x C 2 e fα Remark: T 1 /T 2 - Ratio ration between the greater and the smaller static force in parts of the rope located on either side of traction sheave. C 1 - Coefficient taking account of the acceleration, deceleration and specific conditions of the installation. C 2 Coefficient taking account of the variation in profile of the traction sheave groove due to wear 37 Friction Factor 38
Grooves 39 Angle of Wrap of the ropes Wrapping angle 40
Roping- 1 2:1 Single wrap 1:1 Double wrap 2:1 Double Wrap 41 Roping- 2 1 2 3 42
Roping- 3 43 Roping- 4 44
Traction calculation - 1 T 1 /T 2 C 1 x C 2 e fα Condition: 1. Car stationary at the lowest landing with a load equivalent to 125% (150% for industrial truck loaded freight lift or vehicle lift) 2. Car stationary at the highest landing level, unload 45 Traction calculation - 2 T 1 /T 2 C 1 x C 2 e fα Condition: 3. It shall not possible to raise the empty car when the counterweight is resting on the buffers, and the lift machine is rotated in the up direction 46
Checking of the traction Make sure the balance load correctly This check may be means of measurements of current 47 T 1 /T 2 C 1 xc 2 e fα At each emergency stopping test, complete stoppage of the car shall occur: At ascending, with the car empty, in the upper part of the travel At descending, with the car loaded with 125% of the rated load, in the lower part of the travel In case of the industrial truck loaded freight lifts and vehicle lifts, the traction shall also be checked statically with 150% of the rated load 48
T 1 /T 2 C 1 XC 2 e fα It shall be checked that empty car cannot be raised by the operation of the driving sheave when counterweight rests on its compressed buffers. 49