WIRE ROPE

INSTALLATION, OPERATION AND

MAINTENANCE RECOMMENDATIONS

Matching the Wire Rope with Sheaves and Drums

The ratio of the diameter of the wire rope to the diameter

of operating sheaves and drums (D/d ratio) is particularly

important to service life.  A sheave or drum that is too

small for the rope diameter will cause premature failure

due to bending stresses.

Efficiency falls as the D/d ratio becomes smaller.  This

curve, based on static test data only, illustrates the decline

of bending efficiency for 6 x 19 and 6 x 37 classifications

ropes as the D/d ratio is reduced.

Other

Service life increases as the D/d  ratio becomes larger.

Sheave Diameter Factors

values

This curve, based on bending and tensile stresses only,

Suggested Minimum D/d* Ratios       

are

illustrates the relative performance increase.

*D Sheave Tread Diameter d Nominal 

per 

Rope Construction

Minimum

mitted

6 x 7

42

by

19 x 7

34

vari 

Matching Grooves to the Wire Rope

6 x 19 S

34

ous

Grooves should be spaced so that one wrap of rope does

6 x 21 FW

30

stan 

not rub against the next wrap during operation.

6 x 25 FW

26

dards.

Grooves in sheaves and drums should be slightly larger

6 x 36 WS

23

For

than the wire rope to permit the rope to adjust itself to the

8 x 25 FW

21

exam 

groove.  Tight grooves will cause excessive wear to outer

6 x 41 WS

21

ple

wires; large grooves do not support the rope properly.

ASME

B 30.5 allows minimum hoist rope D/d ratio of 18 and

Wire ropes are manufactured slightly larger than nominal

boom hoist rope D/d ratio of 15.

size.  maximum allowable oversize tolerances are shown

To calculate the recommended or minimum sheave diame 

in the following table.

ter for any given rope, find the rope construction and multi 

ply the rope diameter by the value shown. (Ex.;

Nominal Rope Diameter 

Tolerances

Recommended sheave diameter for a 6 x 19 classification

Inches

Under

Over

wire rope of 3/4  diameter would be 51 x .75 = 38 1/4 )

up to 1/8

0

8%

Rope speed also affects fatigue life.  Higher operating

over 1/8 to 3/16

0

7%

rates require larger sheaves.

Reverse bends from one sheave to another should be

over 3/16 to 1/4

0

6%

avoided.  Other factors that affect bending fatigue life are

over 1/4

0

5%

load, number of cycles and condition of the sheaves and

drums. Consult the wire rope manufacturer for recommen 

dations.

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