Fe 341

1
Fe 341

• Wire Rope Mechanics
• Power
• Interlocks

2
Objectives

• Understand the parts of a wire rope.
• Understand that there are many types of wire
  rope.
• Understand stretch and elastic and plastic limits
  as they relate to safety factors.
• Understand fatigue.
• Understand Factor of safety.

3
Objectives

• Understand horse power and line speed equations.
• Understand engine performance curve.
• Understand power loss through power train.
• Understand torque converter performance curve.
• Understand torque, power, and force equations.

4
Wire Rope Components

• Wire
• Center
• Strand
• Core

5
Wire Rope Construction

• Lay of rope
• Regular lay
• Lang lay
• Right lay
• Right regular lay common

6
Wire Rope Construction

• One size wire
• Warrington
• Seale
• Filler

7
Wire Rope Classification

• 6 x 7 6 strands, 3 14 wires per strand, no
  more than 9 outer wires per strand.
• 6 x 19 6 strands, 15 26 wires per strand, no
  more than 12 outer wires.
• 6 x 37 6 strands, 27 49 wires per strand, no
  more than 18 outer wires, flexible.
• Swedged rotary hammer or dye formed.

8
Wire Rope Flexibility Abrasion

• The more wires per strand, the more flexible the
  rope, and the lower its resistance to abrasion.

Max
Min
6 x 7
A
B
A is abrasion resistance B is bending resistance
6 x 37
Max
Min
9
Wire Rope Strength

• Breaking strength F EFF AM fu
• F breaking strength in pounds.
• EFF rope efficiency which is rope breaking
  strength / the aggregate breaking strength of all
  the individual wires tested separately.
• AM Metallic area of the wire rope.
• fu ultimate stress of the wire in psi.

10
Wire Rope Strength

• The efficiency of rope ranges from 0.65 to 0.95
  however most rope used on logging has an
  efficiency of about 0.9.
•  
• The metallic areas range from 50 to 60 percent of
  the nominal area. 6x 19 rope has a metallic area
  of 0.400d2 for a fiber core rope and 0.465 d2
  for a independent wire rope core rope.

11
Wire Rope Stress and Strain

• Tension causes elongation.
• When tension is low, rope is a spring.
• It stretches under low load then returns to
  nominal length when load is removed. Elastic
  zone.

12
Wire Rope Stress and Strain

• Normal stress is force per unit area, psi.

Wire rope free body diagram
F

• Strain is the elongation of the body per unit
  length.

L
l
13
Wire Rope Stress and Strain
Plastic Zone
Stress
Fracture Point
Yield Point
Elastic Zone

• Stress equation.

Strain

• Strain equation.

Elongation equation.
14
Wire Rope Stress and Strain

• Youngs modulus for logging rope is 10 14 x 10
  6 psi.
• Bending stress.
• Sheave and rope diameters.

15
Wire Rope Stress and Strain

• Rope efficiency

.5
Efficiency Breaking strength bent / breaking
strength straight
1
0
50
Sheave diameter / rope diameter
16
Wire Rope Fatigue and Safety

• Fatigue
• Safety factor

17
Power

• Power (force x distance) / time force x speed
• 1 HP 550 ft lb / sec 33,000 ft lb / minute
• Required HP ((tension in pounds) x (speed in
  ft/min)) / (33,000 ft lb / min)
• Line speed (avail HP) x (33,000 ft lb / min) /
  (mainline tension lbs)

18
Power

• Engine Performance Curve

P
P HP
HP in ft lbs
M torque N engine RPM
M
rpm
19
Power

• Power reductions
• Torque ratio
• Speed ratio
• Efficiency

20
Power

• Torque Converter Performance Curve

E
n
Torque Ratio
M
Speed Ratio
21
Power

• Torque equation
• Power equation
• Force equation

22
Interlocks

• Used on running skyline machines.
• Three types of interlocks.
• Tension in Loggerpc is less than it would be for
  other skyline system types.