Rigging Flashcards
Of the fibre core wire ropes which offers better resistance to deterioration? Vegetable fibre (Manila, sisal, jute) or synthetic fibres (polypropylene) ?
Synthetics
What is IWRC and it’s advantages?
Independent wire core,
Has a separate strand for the inner core. Adds about 7 1/2 % in strength and resistant to crushing
Wire rope is made up of preformed strands. What advantage do the pre formed strands give?
Pre forming strands gives equal load load distribution and helps prevent unraveling when the rope is cut.
What determines the uses for wire rope?
Number of strands
Number of wires per strand
Type or quality of the wire material
Nature of the core
Wire rope that beds around sheeves and drums should have? Why?
Sufficient amount of wires to bend around sheaves and drums.
Smaller wires and strands is more flexible
What are the main considerations when designing a wire rope? To imped the conditions of?
Corrosion
Over tension
Wear
Crushing
And rotation
What grade wire rope is used for mine shaft lifting?
Grade 120/130 and 130/140
Extra extra improved plow EEIP
Extra improved plow (EIPS) wire rope is used when higher breaking strength is needed but the _______ quality is not as good as improved plow IPS
Bending
15% stronger than improved plow
Most common wire rope?
Grade 110/120 improved plow (IPS)
Good west resistance
High fatigue factor
High tensile strength
Grade 100/110 plow wire rope is better for tensile strength or wear resistance?
Wear resistance
The term lay refers to the ?
Direction of winding of both the wires in the strands and the actual rope strands
Regular lay?
Wire in the strands are laid one direction
Strand in the rope are laid in the opposite direction
Lang lay or regular lay? Wire in the strands and wire in the ropes are laid in the same way?
Lang lay
Why is Lang lay best suited for high abrasion situations opposed to hoisting?
Because of its tendency to unwind
What is alternate lay?
A right lay rope wire rope made of alternating strands of right regular lay and right Lang lay strands.
To make a rotation resistant wire rope what would you use?
Outer layers and inner layers are laid in opposite directions
How are wire ropes grouped?
Number of wires per stand.
What does the number wires and patterns define?
The rope characteristics
what are the four common wire rope classifications?
6x7 = 6 strands 3-14 wires per strand
6x19 = 6 strands 16-26 wires per strand
6x37 = 6 strands 27-49 wires per strand
8-19 = 8 strands 16-26 wires per strand
6x7 wire rope uses?
Large wire, not very flexible but good abrasion resistance. should be used on large pully’s or drums. used on permanent guy-lines, ski tows and tram ways
6x19 wire rope uses?
most diverse use. the more wires in a strand the more flexible
6x37 wire rope uses?
most flexible, commonly used on high speed cranes, reeving hoists, power shovels. used where multiple drum layers are needed because of its resistance to crushing
8x19 wire rope uses?
more flexible than 6 strand rope but has poor abrasion resistance, crushes and distorts easily. used with high speed cranes with multiple reeving.
What is one way to check for rope stretching?
mark one strand on top follow it around and mark the top when it comes around. the straight point from lay to lay
Checking wire rope is one of the most important aspects of rigging equipment inspection. What are the purposes of the inspection?
Ensure safety
- ensure components will be replaced only when necessary
- provides advanced warning before something breaks
In severe conditions how often should a wire rope be inspected?
Weekly (daily in some applications)
General uses monthly
What is it called when measuring the width of wire ropes across the widest points
measuring across the crowns
Maximum wire rope reduction?
Number of broken wires in running rope and standing rope?
Personal hoist and material hoist running rope
6 broken wires in one rope lay
3 broken wires in one strand
Standing rope:
3 broken wires in one rope lay. 2 if it is used for personal hoist.
2 broken wires by the connections
When must wire rope be replaced due to wear?
When wire diameter wear is 1/3 or more
What are some causes of bird caging in wire rope?
Pulling through tight sheave
Wound on two small of a drum
Sudden stops
Formula for IWRC ultimate load?
Formula for fibre rope core ultimate load
D x D x 45
D xD x 42
What is the formula for SWL of wire rope?
5:1 swl is for what
General rigging
20:1 swl?
Use if possibility of injury or death due to breakage.
Elevator
Critical lifts with danger to personnel use a ________SWL?
10:1
Working load limit for single vertical hitch?
Full strength
Tension per sling formula?
WxN/LxH
W= weight of load
N = number of slings
L = length of slings if different length always use longest one
H = vertical distance from load to shackle
Ideal sling angles when using multiple slings?
60 degrees best
45 degrees
30 degrees reduces swl by almost 50 percent
Weight capacity of different hitches?
A = 100%
B = 200 %
C = 75 %
If tag is missing on synthetic sling what do you do?
Remove sling from service
Lifting at a 60 degree sling angle creates what kind of triangle?
Equilateral triangle.
All sides are the same
Minimum lifting angle should be no less than _________ degrees
45
A 5 degree sling angle increase the load weight how many times?
6 times
1000 lb load equals 6000lb per sling
When selecting slings for a lift what are some main considerations?
Load weight
Load size
Centre of gravity of the load
Which kind of metal wire rope must be used in a corrosive or acidic environment?
Stainless steel
When are galvanized wire ropes needed?
Salt water applications
Which grade wire rope is most common in mills? What is its breaking strength /load?
Improved plow quality grade
110-120 tons per square inch
Most common lay of wire rope in the industry?
Right regular lay
What are some advantages of Lang lay?
More flexible
Has more area in contact with drum spools or sheaves thus wearing longer.
Disadvantages of Lang lay?
Both ends must be fastened to prevent unwinding
Must not be used with a single part lift
Not to be used with swivels
Cannot be used for slings
Does not resist crushing
What happens when preformed wire ropes are cut?
Nothing, they can be spliced without seizing
When inspecting sheaves for wire rope what are we looking for?
What is a preferred method to lubricate wire rope?
Oil bath lubrication since rope opens up as it goes around the sheave.