Rigging And Lifting Flashcards
What are the advantages of wire rope compared to chain for hoisting? (3)
-stronger
-warning of failure
-shows defects easier
What is FC in terms of wire rope?
Fibre core
What is IWRC or WRC in terms of wire rope?
Independent wire rope cores
The distance along the rope in which a strand makes one revolution refers to what term?
Lay length
What is the most common rope lay?
Regular right lay
What type of lay requires that wires are twisted left into individual strands before twisting right over the main core.
Right regular lay
What lay requires both wires and strands to be twisted the same direction?
Lang lay
What are the advantages of lang lay?
More flexible
Takes longer to wear
Why does lang lay take longer to wear?
More area in contact with the drum spools or sheaves
Disadvantages of lang lay
- both ends permanently fixed
- no single part lift
- no swivels
- no slings
- no resistance to crushing
Describe preformed wire rope
-twist in individual wire and strand to eliminate internal stress.
How are wire ropes classified?
- number of wires per strand
- number of strands
- type of core
- the lay
How is wire rope measured?
Greatest diameter
How do you find the mechanical advantage of a pulley?
The number of ropes that support the moving pulley
Where should the hook be positioned on a lift in regards to the load?
Over the centre of gravity
When using 2 slings where should the centre of gravity of the load be located?
In between the two slings
As the sling angle decreases what happens to the sling stress?
Sling stress increases
On a two legged sling arrangement with an angle of 90 degrees on each sling, what percentage of load will each sling carry?
50% each
(On a 2000lbs load each sling will carry 1000lbs)
On a two legged sling arrangement with an angle of 30 degrees on each sling, what percentage of load will each sling carry?
100%
(With a 2000lbs load each sling will carry 2000lbs)
What is the recommended safe working angle for slings?
60 degrees
What angle should slings never be used at?
45-30 degrees or less
How can you ensure your sling angles are always greater than 60 degrees from the horizontal?
By ensure your length of sling is greater than the space between slings.
The term for use of tools or mechanical devices to multiply force, is what?
Mechanical advantage
When using two slings to hoist a load at what angle to horizontal is the stress on the slings the least?
90 degrees
When using two slings to hoist a load, what happens to the sling stress as the sling angle to the horizontal decreases?
The sling stress increases
The point at which an object will balance is what?
The centre of gravity
How can the mechanical advantage of a pulley system be described?
The effort distance compared to the resistance distance
If a load is rigged with the centre of gravity off to one side what will happen when it’s hoisted in the air?
The load will tilt until the centre of gravity is directly below the hook
What happens if you hoist an object with the centre of gravity above the lifting points?
The load could topple
What is the safe and proper procedure if during a hoist the load tilts more than 5 degrees
Lower the lift and rearrange the rigging
What is the mechanical advantage of a block and tackle with two sheaves on the fixed block and two sheaves on the travelling block?
4:1
Where is the safety system located on the block and tackle?
It has no safety system
What lifting device is designated to pull in all positions, uses self energizing jaws, and has an unlimited amount of cable travel?
The tirfor
What is the safety system found in the tirfor?
A shear pin breaks and seizes the load when overloaded
What is the safety feature found on a cable-type come along?
Handle bends when overloaded
What feature does the OHS regulation require on all trolleys?
Drop stops
How is the size of a Jack designated?
By capacity
What are slings designed to do?
Connect a load to a lifting device
What type of rope lay is in the picture?
Right regular lay
Wha type of rope lay is on the right?
Right lang lay
What type of rope lay is on the right?
Left regular lay
What term refers to the measure of rope at its thickets point?
Diameter
How is chain size determined?
By the diameter of the rod that is used to form each link
A higher grade number on a chain indicates what?
Greater break strength
What is the lowest grade chain that can be used for hoisting?
Grade 80
If you need to protect a load from marring what sling would you use?
Fibre web sling (normally synthetic)
What are the two primary functions of a snatch block?
Change the direction of a rigging cable
Increase pulling power
What is the mechanical advantage of a snatch block?
2:1
What is the angular pull limit of a shouldered eyebolt?
Min 45 degrees
What does WLL stand for?
Working load limit
What is the working load limit of an eyebolt (shouldered) at a 45 degree pull from vertical?
75% reduction in WLL
What is the working load reduction of an eyebolt (shouldered) at a 15 degree pull from vertical?
45% reduction in WLL
What are the 3 basic types of pins available for both shackle classes?
- screw
- round
- safety type
What are the 2 classes of shackles?
- anchor (bow)
- chain (D)
How do you prevent side loading a shackle?
Packing washers
How much does the crimping action of a cable clip reduce the breaking strength of wire rope? (%)
- 20%
What is the formula for the number of cable clips to be used?
= diameter of wire rope x 3 +1
(Dx3+1)
What is the formula for finding the spacing of clips on wire rope?
= diameter of rope x 6
( Dx6)
How much does a incorrectly installed cable clip reduce the breaking strength of a wire rope? (%)
50%
What are the 3 most common hook types?
-slip
-grab
-sorting
What are grab hooks designed to do?
To grab onto chain links
To protect from the stress of twisting while under load all hoisting chains should be equipped with what?
Swivels
What are the 3 basically types of hitches?
Vertical
Choker
Basket
A vertical hitch with 2 or more legs is called what?
Bridle hitch
How many legs are supporting a load on a 6 legged bridle hitch?
Max 2
How much does using a choker hitch reduce the capacity of a sling?
Min 25%
What can you use to protect a sling from sharp corners?
Softeners
When is a single choker hitch NOT recommended
Loose loads as it can push loose items up and out of the choker
At what load length is it best to use a double choker?
When items are more than 3M (10ft) long
What type of choker should be used to lift a bundle of loose items?
Double wrap choker hitch
What happens to the capacity of a sling when using a basket hitch?
It doubles
When should single basket hitches NOT be used?
When a load could tilt or slide out of the hitch.
What angle should the legs of a double basket hitch be at?
At least 60 degrees or more
What basket hitch can be used for loose loads?
Double wrap basket hitch
What is the purpose of a spreader bar?
To create a more ideal angle to the slings attached. (Thus prevent tipping or sliding)
What is the purpose of an equalizer bar?
To ensure a load is distributed evenly.
Specifically helpful for tandem lifts
What happens to nylon slings when they are wet?
Strength is decreased
How many distributed broken wires in one rope lay would require it to be removed from service?
6
How many broken wires in one strand in one rope lay would require it to be removed from service?
3
How many broken wires near a fitting need to occur for a rope to be removed from service?
1.
In wire rope terminology what does “one rope lay” refer to?
The lengthwise distance for one strand revolution
What is it that enables both of the threaded rods in a turnbuckle to simultaneously tighten or loosen while turning the sleeve in one direction?
LH threads on one side RH on the other
What type of synthetic sling has metal triangles of equal size on each end?
Basket web sling
What type of sling is best for loads that are abrasive or hot and require a wide bearing surface?
Metal mesh sling
What is the maximum pull angle that a shoulder eyebolts are able to withstand
45 degrees to the vertical
When several slings are to be attached to a single hook, what is used to make the connection to the hook?
Shackle
To prevent cross-bow loading what is the maximum angle between any two slings at a shackle?
45 degrees
Besides allowing the rigger to quickly connect a shocker hitch to a load what other purpose does the design of a choker hitch serve?
Protects the sling from sharp ends at the choker point
What part of the loop must the U-bolt part of a cable clip grab onto?
Dead end of the rope
What determines the amount of cable clips required for a connection?
Diameter of the rope
What style of hook is designed so the throat fits between the links of a chain?
Grab
What is a rigging softener?
Pad used to protect a sling from sharp corners of a load
When lifting a bundle of pipes horizontally with slings what hitch would be recommended?
Double wrap basket hitch
What is the recommended safe lifting angle? (from the horizontal)
60 degrees
What is it called when continuous pounding of a wire rope causes strands to become flattened, distorted, and brittle.
Peening
What is the term to describe the displacement of wires and strands as a result of wire rope rubbing against itself?
Scrubbing
What can result from sudden stops or the wire rope being pulled through tight sheaves or winding on too small of a drum?
Bird caging
What is the minimum amount of loops to be on a rope drum?
3
How are cranes usually identified?
Construction of boom
Type of carrier
What does this signal mean?
Raise load up (cable up)
What does this signal mean?
Emergency stop
What does this signal mean?
Lower boom
What does this signal mean?
Lower the boom and raise the load (lower boom maintain load)
The wrapping applied at the end of a rope to prevent the rope strands from unraveling is called what?
Whipping
A __________ secured two ends of the same rope
Knot
A __________ is a knot that joins two separate ropes together
Bend
A ____________ attaches a rope to an object like a rail, post, or ring
Hitch
What is the portion of the rope that form the loop termed?
Bight
A long portion of rope is called what?
Standing part
What type of know is this?
Bowline knot
What type of knot is this ?
Reef or square knot
What kind of knot is this?
Double sheet bend
What type of knot is this?
Clove hitch tied in position
What type of knot is this?
Figure 8
Or
Stopper knot
What type of knot is this?
Non slip loop
What type of Manila rope has one or more coloured strands?
Number 1 grade
Which type of dry rope has the best electrical insulating properties?
Polypropylene
Up to how much will nylon rope stretch when loaded to the breaking point?
40 % of its original length
How should you remove new rope from its shipping coil?
Pull it from inside of the coil
What is the maximum load that should be imposed on a rope for rigging?
1/5 it’s breaking strength
How much can sharp bends and knots reduce the strength of a rope by?
50%
When knot tying what do you call the portion of rope that forms the loop?
Bight
What knot acts like a pulley for tying down a load?
Tuckers knot
What knot, hitch, or bend would you use to join a large diameter rope to a small diameter rope?
Sheet bend
What knot hitch or bend would you use to join two ropes of the same diameter?
Reef knot
How is wire rope classified (4)
- # of wires per strand
- # of strands
- type of core
- the lay
Why does wire rope need to be lubricated?
The rope will deteriorate rapidly without it
What is the two groups of fibre rope?
Synthetic
natural
Why are synthetic fibre ropes preferred over natural fibre ropes in most industries today?
Strength
Shock load capacity
Resistance to weathering
Why is the use of braided rope increasing
Stretch resistance
Normally stronger
Why must special care be used when hoisting with chain?
Can break without warning
How much wear is tolerated on a chain used for hoisting that is under 1” diameter.
5% wear
How much wear is tolerated on a chain used for hoisting that is over 1” diameter.
10% wear
What type of wire rope socket does NOT give 100% efficiency?
Wedge sockets (70%)
What is used in poured sockets?
Zinc (or spelter)
Sometimes epoxy
If a thimble is not used on a spliced eye how much is the efficiency of the connection reduced?
10%
Improper application of even one cable clip reduces the efficiency of the rope by how much?
40%
How do you find the number of cable clips required?
Diameter of rope x 3 + 1
(Dx3+1 = # of clips)
How do you find the spacing of cable clips?
Diameter of rope x 6
(Dx6 = spacing of clips)
How is a shackle size determined?
The diameter of the bow section of the shackle
When using a screw pin shackle before hoisting what should you do?
Mouse it. (Lock wire)
Instead of wrapping the ends of synthetic rope with twine whipping what may you use?
Heat to melt the fibres
Which of the knots forms a non slip loop?
Bowline
When making an eye in wire rope with U bolt clips where must the saddle be located?
Live end of the rope
What type of knot or bend is used for tying two ropes of different diameters?
Sheet bend
What would you do if one outrigger of a crane started to sink?
Set down more blocking area and re level
Limit of approach is what?
How close a crane can come to hazardous objects
What is required for a load to be most stable?
Centre of gravity below the hook and sling attachment
What must be fastened by the manufacturer in clear view in the cab of a crane?
Load capacity chart
Before using a chain sling what should you do?
Do a link by link inspection of the chain
What is the maximum line pull for a snatch block rated for 5 tons max?
2.5 tons
If a 2 ton load is lifted with a two legged bridle hitch at 30% horizontal angle what swl do your slings need to be?
2 tons each
