LECTURE 9 ROPE DRIVES THEORY.pdf

1. 1
MANIPAL
(A constituent institution of MAHE, Manipal)
A.AMAR MURTHY

2. Introduction
Uses of wire
ropes
Construction of
wire ropes
Guidelines for the
selection of wire ropes
Contents
Specification of
wire ropes
Advantages
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3. 3
WIRE ROPE
• Wire rope is a flexible cable, which consists of several
strands of metal wires.
• Earlier the wires were made of wrought iron, but
now steel wires are used, which are twisted to form a
helix.
• Wire ropes of diameter less than 9.5 mm are called
cables.
• Use of wire ropes is quite old since 1830s, when these
were used for mining hoist applications.
strands
wire core
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4. 4
USES OF WIRE ROPE
Typical use of wire ropes can be seen in many
applications like:
i. Lifting cranes, lifts, and hoisting applications;
ii. In mechanisms, like clutch and gear wires,
connections from airplane cockpit using levers
and pedals to different parts;
iii. In pre-stressed concrete bridges, use of static
steel wire ropes can be seen; and
iv. Suspension bridges use steel wire rope between
two towers at extreme ends.
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5. 5
ADVANTAGES OF WIRE ROPES
i. High strength to weight ratio
ii. Silent operation even at high velocities
iii. Greater reliability.
iv. High efficiency
v. Longer life than fiber ropes
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6. 6
Construction of wire rope
Source: https://www.convergencetraining.com/blog/wire-rope-lay-classification-and-construction
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7. 7
Construction of wire rope
• The construction of wire rope is shown in fig.1(a) and (b).
• The wire rope consists of number of strands
• Each strand comprising several steel wires.
• The number of wires in each strand is generally 7,19 or 37
• The number of strands is usually six
• The individual wires are first twisted into the strand and
then the strands are twisted around a fibre or steel core.
Fig. 1(b) 6 x 19 (12/6/1)
Source
fig. 1(a) https://images.app.goo.gl/fcPFfCr2pEqgavQG7
fig. 1(b) https://images.app.goo.gl/WUZdWmn4hfHc7uqG8
Fig. 1(a) 6 x 7 (6/1)
Strand
Strand
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8. 8
TYPE OF CORE
Wire rope cores are designated as:
• Fiber Core (FC)
• Independent Wire Rope Core (IWRC)
• Wire Strand Core (WSC)
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The rope core is the central element of a
round rope around which are laid helically
the strands of a stranded rope.

9. 9
Symbols for rope cores
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fibre Core fibre Core
natural fibre core
synthetic fibre core
FC
NFC
SFC
steel core steel core
wire Strand core
wire rope core
independent wire rope core
WC
WSC
WRC
IWRC

10. 10
Specifications of wire ropes
• The specification of wire ropes includes two
numbers, such as 6 x 7 or 6 x 19 .
6 x 7 (6/1)
number of strands in
the wire rope
number of steel
wires in each strand
10
6 x 19 (12/6/1)

11. 11
Wire rope components 11
Source :http://www.ushamartin.com/wp-content/uploads/2014/04/Wire-Rope-Handbook.pdf

12. 12
ROPE LAY
• The lay of the rope refers to the manner in
which the wires are helically laid into
strands and the strands into the rope
• The lay direction of the lay wires in the
strand can be right or left
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Lay direction of wires in a strand

13. 13
ROPE LAY
Image source https://images.app.goo.gl/sixzpy6kab3pAyG66
Lang-lay
If the wires in the strand are twisted in the
same direction as the strands
Regular-lay
If the wires in the strand are twisted in a
direction opposite to that of the strands.
Lang-lay
Regular-lay
Regular-lay ropes are more popular than the Langs-lay ropes.
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14. 14
Guidelines for the selection of wire
ropes
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15. 15
Guidelines for the selection of wire
ropes
i. Strength of the wire rope
depends upon the tensile strength of the individual wires.
ii. Flexibility of the wire rope
achieved by using a large number of small-diameter wires.
iii. Abrasion resistance
this is governing factor when the wire is likely to drag through gritty material or
across a stationary object
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END OF SLIDE
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