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Millwright Manual > Chapter 7 - Rigging And Lifting > Flashcards

Chapter 7 - Rigging And Lifting Flashcards

1
Q

Name one important advantage of wire rope, as compared to chain, for hoisting

A
  • strong and gives good warning of failure when it is defective
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2
Q

How is the following achieved in the construction of wire rope:
- crush resistance

A
  • steel-core rope resists crushing better than fibre-core rope
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3
Q

How is the following achieved in the construction of wire rope:
- abrasion resistance

A
  • large diameter wires on the outside or contact layer have better abrasion resistance than small wires
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4
Q

How is the following achieved in the construction of wire rope:
- flexibility

A
  • the more wires in the strand, the more flexible the rope will be
  • the more strands in the rope, the more flexible the rope will be
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5
Q

How is the following achieved in the construction of wire rope:
- strength

A
  • steel core rope is stronger than fibre core

- for a given diameter rope, the fewer wires in a rope, the greater the strength

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6
Q

How is the following achieved in the construction of wire rope:
- corrosion resistance

A
  • galvanized rope must be used in salt water applications

- stainless steel must be used in a corrosive, acidic environment

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7
Q

Which grade of wire rope is most commonly used in industry and what is its strength?

A
  • improved plow quality grade

- - breaking load of 110-120 tons per square inch

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8
Q

Describe the following terms:

- FC

A
  • Fibre cores (FC)
  • usually made from sisal, polypropylene or other synthetic rope material
  • manufacturers can supply wire rope with an oil-impregnated fibre core to self-lubricate the inner wires
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9
Q

Describe the following terms:

- IWRC or WRC

A
  • Independent wire rope cores (IWRC) or wire rope cores (WRC)
  • used when wire rope is subject to sudden heavy loads, crushing, or heat
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10
Q

Describe the following terms:

- strand core

A
  • in small-diameter wire ropes, the wire rope core is replaced by a strand core
  • stand cores use another strand of the rope as core
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11
Q

What is a lay length?

A
  • refers to the distance along the rope in which a strand makes one revolution
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12
Q

Describe the construction of right regular lay wire rope

A
  • consists of a number of wires twisted to the left around a small core to form each of the six strands
  • these strands are then twisted to the right around the main core to form the final rope
  • wire ropes of six strands are the most common
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13
Q

How is Lang’s lay rope constructed and what are its advantages and disadvantages?

A
  • has the wires and strands twisted in the same direction. The core design is the same as that of the regular lay.

advantages

  • is more flexible than regular lay
  • has more area in contact with the drum spools or sheaves, thus wearing longer

disadvantages

  • both ends must be permanently fastened to prevent unwinding
  • it must not be used with a single-part lift
  • it must not be used with swivels
  • it cannot be used for slings
  • it does not resist crushing
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14
Q

What are the advantages of preformed wire rope?

A
  • have the twist or helix set in each wire and strand to eliminate internal stress
  • do not fly apart when cut
  • can be spliced without seizing (binding)
  • when wires break they lie flat in position on the rope
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15
Q

How is wire rope classified?

A
  • the number of wires per strand
  • the number of strands
  • the type of core
  • the lay

example - 6 x 31 Warrington Seale, IWRC Right, regular lay

6 - number of strands
31 - number of wires per strand
Warrington Seale - indicates the configuration of wires in each strand
IWRC - indicates the type of core used in the rope: Independent Wire Rope Core
Right, regular lay - specifies the way wires and strands are wound

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16
Q

How is the size of wire rope measured?

A
  • measured across its greatest diameter
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17
Q

Describe how to:

- choose the right rope

A
  • ensure that the correct size and type of rope is used

- ensure that the rope is in good condition

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18
Q

Describe how to:

- maintain the rope properly

A
  • inspect the rope regularly according to the manufacturers guidelines and WBC Regulations
  • discard damaged or kinked sections by cutting them out
  • to remove rope that is worn due to vibration, cut off a section next to the anchorage and refasten the rope
  • lubricate the rope regularly according to manufacturer’s recommendations
  • store all unused rope in a clean, dry place, where it will be protected from the element
  • minimize uneven wear by moving the rope at regular intervals so that different sections of it are at the critical wear points
  • change layer and crossover points by cutting a few feet of rope from the drum end and refastening it. Make the cut long enough to:
    • change the layer at least one full coil from its former position
    • move the crossover points one-quarter turn around the drum
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19
Q

Describe how to:

- use the rope correctly

A
  • never overload the rope
  • avoid shock loading
  • apply the power smoothly and steadily
  • ensure that the rope winds properly on the drum
  • ensure that rope ends are properly seized
  • ensure wire rope has a run-in period before operating at full load and full speed
  • on equipment having multiple falls of other than non-rotating ropes, a new rope will stretch and unlay slightly, causing turns to appear in the load block. If the anchorage is not fitted to a suitable swivel, disconnect it, removed the turns, and reconnect the anchorage
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20
Q

Describe how to:

- use related equipment correctly

A
  • check flanges for wear, chips and cracks
  • a proper fitting sheave groove should support the rope over 135-150 degrees of rope circumference
  • check grooves for proper size
  • check sheave grooves for wear
  • repair or replace faulty guides and rollers
  • inspect sheaves and replace those that have deeply worn or scored grooves, or have cracked or broken rims
  • use thimbles in eye fittings at all times
  • if the sheaves or drums bear the imprint of the rope, they should be machined clean or replaced with harder material
  • check sheave and roller bearings for free operation. Sticking will cause unnecessary wear
  • check the fleet angle. An excessive fleet angle will cause severe abrasion on the rope as it winds onto the drum, severely shortening rope life
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21
Q

Why does wire rope need to be lubricated?

A
  • If it is not regularly lubricated, the rope will deteriorate rapidly in the following ways:

– the wires become embrittled from excessive corrosion and break easily (embrittled means made more brittle by molecular change)

– the wires in a rope are subject to frictional wear as they move together during operation. Lack of lubrication increases wear and reduces strength

– ropes not in regular service or those not considered as operating ropes are vulnerable to weathering. If the weathering wears through the external lubrication, excessive moisture can gradually leach out the internal lubricant. This causes the core and wires to rust and deteriorate

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22
Q

Describe how a wire rope is lubricated

A

1 - ensure that the rope is clean and dry before the lubricant is applied

2 - use a light, penetrating cleaner to soften the built up grime before removing it. Contact the lubricant supplier regarding the proper cleaning oil to use. Do not use gasoline or kerosene, since too much of it will remove the internal lubricant

3 - the main objective in external lubrication is to fill any gaps in and between the strands so that a complete seal is provided. The frequency required depends on the particular installation

4 - apply the lubricant using one of the following methods depending on the viscosity of the compound applied, the length of rope involved and the limitation of the facilities:

4a - light oils
– apply light oils by brushing, running the rope through an oil bath, spraying, drip method or mechanical force feed

4b - medium and heavy oils
– apply medium- or heavy-weight lubricants warm. Apply them by brush or by running the rope through a funnel containing the lubricant. Or use an air blast provided that only dry air is used and all safety precautions are taken

5 - even though brushing and dripping methods of lubricating long ropes are tedious, they give you time to inspect the rope

6 - the rope should be properly lubricated at all times. Inspect the rope often to see when it must be done

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23
Q

Describe the correct method of unwinding wire rope from a spool

A

1 - a quick way of mounting a spool is to use a length of pipe and some blocking

2 - do not take wire rope off the side of the spool a wrap at a time, as this often results in kinks

3 - when taking a length of wire rope from a spool, rotate the spool on a spindle or turntable, or roll the spool along the floor

4 - before cutting a length of wire rope from a reel, “seize” or wrap each side of the proposed cut. Use friction tape, or, if the end is the be welded, light wire. If one end of the wire is to go through a hole in a drum, a good practice is to “braze” or weld the end and then remove the seizing

5 - if using an impact cutter to cut the wire rope, keep the cutter in the same position throughout the cut

6 - after removing a length of rope from a spool, wind the slack back onto the spool and tie down the free end

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24
Q

Determine the anchorage point on a drum for a right-lay-overwound rope

A
  • to obtain good drum winding, the rope must be started from the proper flange. Deciding which flange to use depends on whether the rope is left-lay or right-lay, and whether the rope leads from the top or from the bottom of the drum
  • standing behind the drum, use the rule of hand:

1 - the right hand represents right-lay rope

2 - the index finger shoes the approach of the ropes

3 - the position of the back of the hand indicates whether the rope is overwound or underwound

4 - the position of the thumb shows where the rope is attached to the drum

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25
Q

List the two groups of fibre ropes

A
  • natural fibres

- synthetic fibres

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26
Q

Describe the construction of fibre rope

A
  • the usual method of construction for fibre rope is Reverse Twisting. The method of construction is as follows:

1 - fibres from 6-20 feet long are combed to bring them parallel to each other
2 - a definite number of fibres are right-hand twisted to form a yarn
3 - a number of yarns are then left-hand twisted into a strand
4 - three or four of these strands are right-hand twisted to form the rope

  • This twisting pattern results in a right-lay rope. Reverse order of twisting produces a left-lay rope
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27
Q

Compare soft-laid to hard-laid fibre rope

A
  • The varying degrees of tightness of the twisted yarns and strands determine whether it is a hard-laid, medium-laid (common or standard) or soft-laid rope
  • soft-laid rope has the greatest tensile strength but gives poor service if run over sheaves, and it does not withstand abrasion well
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28
Q

Why are synthetic rope fibres preferred over natural fibre ropes in most industries today?

A
  • strength
  • shock-loading capacity
  • resistance to natural weathering
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29
Q

How are knots secured in synthetic rope?

A
  • finish all knots with an additional safety knot to prevent slippage
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30
Q

What are the advantages of polypropylene compared to nylon rope?

A
  • buoyant and therefore used a great deal around water
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31
Q

Why is the use of braided rope increasing?

A
  • does not stretch as much as other types of rope

- certain types of braided rope are stronger than many laid ropes of the same fibre

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32
Q

How is the size of fibre rope determined?

A
  • measured by diameter or by circumference
  • up to 1 inch - measured by diameter
  • over 1 inch - measured by circumference
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33
Q

What is the safe working strength of a new fibre rope with a breaking strength of 1000lbf?

A
  • for new rope, the working strength is 1/5 of the breaking strength
  • for used rope, increase this safety factor
  • 200lbf SWL
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34
Q

How should fibre rope be stored?

A
  • store rope in a dry room away from moisture and any extreme heat
  • if possible, hang a rope on a large wooden peg to ensure air circulation
  • dry rope thoroughly before storing it
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35
Q

Recognize and describe the uses of the following knots and hitches:
- overhand knot

A
  • starting point of many knots

- frequently used as a stopper at the end of a rope

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36
Q

Recognize and describe the uses of the following knots and hitches:
- figure-of-eight knot

A
  • used at the end of a line to prevent the end from slipping through a fastening or loop in another line
  • should be used to finish off other knots, especially when using synthetic ropes
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37
Q

Recognize and describe the uses of the following knots and hitches:
- square or reef knot

A
  • used for tying together two lines of the same size so that they will not slip
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38
Q

Recognize and describe the uses of the following knots and hitches:
- bowline

A
  • knot most commonly used for forming a loop in the end of a line
  • easy to tie and untie
  • will not slip
  • can be used to secure loads without crushing them
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39
Q

Recognize and describe the uses of the following knots and hitches:
- bowline-on-the-bight

A
  • used for putting a non-slip loop anywhere between the ends of a rope
40
Q

Recognize and describe the uses of the following knots and hitches:
- round turn and two half hitches

A
  • one of the most efficient and most used knots
  • can be used wherever a line must be made fast
  • wrapped once around and hitched twice on load line and then seized
41
Q

Recognize and describe the uses of the following knots and hitches:
- becket hitch

A
  • used for making a line fast the the becket of a block or to a ring
42
Q

Why must special care be used when hoisting with chain?

A
  • use chain for hoisting only when no other method of slinging or rigging is available
  • use chains in hoisting operations only when their ability to withstand hight temperatures and abrasion is required
  • chains can break without warning - only one line in a chain needs to break for the load to drop
43
Q

What grade of chain is acceptable for overhead hoisting?

A
  • Grade “A”

- each link must bear an “A” stamped into its surface

44
Q

How much wear is tolerated on a chain used for hoisting?

A
  • chains show sings of wear at the bearing surfaces of each link

STOP using the chain when:

  • when wear equals 5% of the link diameter for chains less than 1”
  • when wear equals 10% of the link diameter for chains over 1”
45
Q

What are load-rated fittings?

A
  • the safe working load is stamped on the fitting
46
Q

Describe the following wire rope and fittings and state the efficiency where possible:
- poured sockets

A
  • zinc (or spelter) sockets are standard drop-forged sockets
  • permanent terminal attachments for wire rope
  • used to secure cabes onto passenger or freight elevators
  • when properly attached = 100% efficient
  • epoxy resins are also used for poured sockets
47
Q

Describe the following wire rope and fittings and state the efficiency where possible:
- cappel sockets

A
  • when properly installed and frequently inspected = 100% efficiency
  • efficiency depends entirely upon the wedges being kept tight
  • allow easy, frequent inspection of the whole section of rope where it is gripped
48
Q

Describe the following wire rope and fittings and state the efficiency where possible:
- wedge sockets

A
  • intended for on-the-job attachment and for quick rope replacement. Main advantage are ease and speed of applying and detaching
  • used to secure a ball or hook on a mobile crane
  • low efficiency = 70% of the strength of rope
  • important to secure the dead end properly
    • load-line straight with eye
    • dead-end looped and clipped on itself (not clipped to load-line)
49
Q

Describe the following wire rope and fittings and state the efficiency where possible:
- swaged sockets

A
  • permanent terminal attachments for wire rope
  • made by compressing a steel sleeve over the rope with a hydraulic press
  • properly made = 100% efficiency
50
Q

Describe the following wire rope and fittings and state the efficiency where possible:
- eyes and thimbles

A
  • eyes in various forms are frequently used as wire-rope end attachments
  • with the exception of some slings, all eyes must include rope thimbles to maintain rope strength and to reduce wear
  • if a thimble is not used on a spliced eye, the efficiency is reduced by 10%, because the rope flatten, crush and wear under load
  • with a thimble in the eye the rope is completely protected and retains it shape
  • the WCB requires the identification of each eye formation with tags
51
Q

Describe the following wire rope and fittings and state the efficiency where possible:
- cable clip connections

A
  • used to make or attach a wire rope to a piece of equipment
  • various types:
    • U-bolt (saddle) clips
    • double-saddle (safety or fist-grip) clips
    • double base-clamps
  • when installed properly = 80% efficiency
  • improper application = 40% efficiency

Clamp force and rope wear = double-base clamps > double-saddle clamps > u-bolt clip

  • the number of clips required is determined by the rope diameter

INSTALLATION:
1 - apply the first clip at the the end of the looped line
2 - apply the second clip against the eye and thimble
3 - apply all other clips in between
4 - apply tension towards eye and tighten clips

  • never saddle a dead horse
  • never use any kind of clip to directly connect two straight lengths of rope - forms two eyes (with thimbles) and connect the eyes with a shackle
52
Q

What safety concerns and procedures apply to all hooks?

A

1 - they are forged alloy steel and generally are stamped with their rated safe working loads (SWL)

2 - make sure that all hoisting hooks (except grab and sorting hooks) are equipped with safety catches

3 - inspect all hooks frequently:

    • look for wear in the saddle of the hook
    • look for cracks, severe corrosion and twisting of the hook body
    • measure the throat opening, if any opening or distortion, destroy the hook

4 - commonly used types of choker hooks are standard, adjustable and dual-sliding

5 - make sure the loads are balanced on the hook

    • balance load = 100% efficient
    • 1/2 off-centre = 80% efficient
    • point-loading = 40% rated load
  • recommended that all hoisting hooks be equipped with swivels and headache balls
53
Q

How is shackle size determined?

A
  • sized by the diameter of the steel in the bow section
54
Q

What precautions should be taken when using shackles?

A
  • all pins must be straight and all screw pins must be completely seated. Cotter pins must be used with all round pin shackles
  • never replace the shackle pin with a bolt; use only the proper fitted pin. Bolts are not intended to take the bending that is normally applied to the pin
  • destroy worn shackles
  • when using a screw pin shackle, secure the pin with wire through the hole to the shackle body to prevent the pin from unthreading (turning out)
  • never allow a shackle to be pulled at an angle. Centralize whatever is being hoisted on the pin by using suitable spacers
  • do not use screw pin shackles if the pin can roll under load and unscrew

INSPECTION:

  • check for bow wear
  • check for pin wear and straightness
  • check that pin is always seated
  • check that shackle is not “opening up”
55
Q

Describe the material and method of fabricating eye bolts for hoisting

A
  • should be of forged alloy steel and equipped with shoulders or collars (shoulder-type eye bolts)
  • the plain (shoulderless) eye bolt is acceptable for vertical loading only
  • Any angled loading severely reduces SWL of both shoulder- and shoulderless-eyebolts
56
Q

What procedures should be followed for hoisting with eye bolts?

A
  • Check SWL of eyebolts to load
  • the shoulder firmly contacts the working surface (you may need to use washers)
  • the nuts are properly torqued
  • the tapped hold for the bolt has a minimum depth of one and one-half (1.5) times the bolt diameter
  • the thread in the tapped hole and on the bolt are in good condition
  • when using an eye bolt to lift, keep bending to a minimum
  • always apply loads to the plane of the eye, especially when bridle slings are used
  • always use a shackle and ensure that the lifting angle is above 45* degrees
  • where eye bolts cannot be kept in line with each other when tightened, insert washers or shims under the collars to align eye bolts while maintaining proper tightness
57
Q

Describe the construction of turnbuckles

A
  • may have end fittings that are: eyes, jaws, stubs, hooks, or a combination
  • rated loads depend upon the outside diameter of the threaded portion of the end fitting and on the type of end fitting
  • hook types have reduced rating capacity
  • should be weldless construction and fabricated from alloy steel
58
Q

Describe the procedure for using turnbuckles for hoisting

A
  • if using a turnbuckle with hook end fittings:
  • -if there is no safety catch, mouse the throat of the hook to prevent rigging from slipping off
  • if using turnbuckle where there is vibration:
  • -lock the frame to the end fittings to prevent it from turning and loosening
    • use lock-wire to ensure that the turnbuckle will not loosen. Lock- or jam-nuts are not effective
  • when torquing a turnbuckle, apply the same torque for a bolt of equal size
  • inspect frequently for:
    • cracks and bends, especially at the neck of the shank
    • deformed and bent rods and bodies
    • deformed end fittings
    • cracks and bends around the internally thread portion
    • signs of thread damage
59
Q

Describe the purpose of:

- a spreader beam

A
  • used to support long loads during lifts
  • remove the risk of load tipping, sliding or bending
  • remove the possibility of low sling angles and the tendency of the slings to crush the load
60
Q

Describe the purpose of:

- an equalizer beam

A
  • used to equalize the load on sling legs and to keep equal loads on dual hoist lines when making tandem lifts
  • fabricated to suit a specific application
61
Q

To what specifications should equalizer beams conform?

A
  • must meet WCB specifications
62
Q

What purpose do slings serve for hoisting?

A
  • serve to connect the load to the lifting device
63
Q

How are slings protected from sharp corners?

A
  • place padding or soft corners (preformed metal brackets) between the sling and any sharp corners on the load
64
Q

On a multi-leg (3+) bridle hitch, do all the legs share the load equally?

A
  • when a bridle hitch has more than two legs you cannot assume that all legs are sharing the load equally
  • the full weight of the load might be shared by only 2 legs
  • the other legs may simply be balancing the load
65
Q

Describe the purpose of the following sling configurations:

- single vertical hitch

A
  • consists of a single leg of sling material with a hook and an eye at each end
66
Q

Describe the purpose of the following sling configurations:

- bridle hitch

A
  • two or more vertical hitches may be used together to form a bridle hitch
  • used on loads which provide suitable attachment points
  • the load will be stable if the attachment points are above the load’s centre of gravity
67
Q

Describe the purpose of the following sling configurations:

- single basket hitch

A
  • made from a single length of sling material passed through a load
  • both ends of the sling attach to the main hook
  • do not use on loads which could tilt and slide out of the hitch
68
Q

Describe the purpose of the following sling configurations:

- double basket hitch

A
  • loads which require support from underneath
  • locate the double basket hitch so that the load is balanced between the two points of support
  • keep the two support points far enough apart so that the load cannot tip and slide out
  • NEVER incline the legs of a double basket hitch less than 60* degrees to the horizontal
    • this will prevent the legs from sliding towards each other.
    • use longer slings to spread the legs apart without having the legs at an excessively low slope
69
Q

Describe the purpose of the following sling configurations:

- double-wrap basket hitch

A
  • secure loose loads
  • sling is wrapped completely around the load
  • double wrapping presses all the components together, preventing even the top pieces from sliding out of the rigging
70
Q

Describe the purpose of the following sling configurations:

- single choker hitch

A
  • made with a single length of sling material hooked back to itself just above the load
  • will not totally secure the top of loose loads
71
Q

Describe the purpose of the following sling configurations:

- double choker hitch

A
  • long loads or loose loads which need to be lifted level
72
Q

Describe the purpose of the following sling configurations:

- double-wrap choker hitch

A
  • similar to the double-wrap basket hitch in that both squeeze the load from all sides
  • will secure the top of loose loads
  • may be used singly or in pairs
73
Q

Describe the purpose of the following slings:

- endless slings

A
  • can be used in a variety of configurations
  • made of fibre rope or synthetic webbing
  • light to handle and do not damage the loads
  • subjected to sharp bends and tend to deteriorate rapidly
74
Q

Describe the purpose of the following slings:

- synthetic web slings

A
  • Available in a variety of shapes and widths:
    • endless
    • standard eye
    • twisted eye
    • basket web sling - metal triangles of equal size on each end of webbing
    • choker web sling - has a larger triangle containing a slot at one end and a smaller triangle at the other end. The smaller triangle can be passed through the slot of the larger triangle to form a choker hitch
  • relative softness and width protect the loads they are lifting from being marred or scratched by the sling
  • heat and friction damage synthetic slings
75
Q

Describe the purpose of the following slings:

- metal mesh slings

A
  • loads which are too abrasive or too hot for synthetic webbing, yet require the wide bearing surface of a web belt
  • usually equipped with triangle ends which permit the use of either a basket or choker hitch
76
Q

What is the relationship between the safe working load (SWL) and the breaking strength of the slings used for hoisting materials?

A
  • If you are lifting materials and equipment, they must be no heavier than 1/5 the breaking strength
  • if you are lifting people, they must not be more than 1/10 the breaking strength
  • manufactured slings have their SWLs listed on tags
  • slings built on the job, you must calculate the SWLs and never exceed them when lifting
77
Q

Calculate the SWL for a 5/8” diameter wire rope

A
  • rule of thumb for calculating the SWL of wire rope is:
    • 3/8” will support 1 ton
    • additionally each 1/8” increase in diameter is equal to 1 ton increase in SWL

SWL:
5/8” = 3/8” + 1/8” + 1/8” = 3 ton = 6000lbf

78
Q

How much does a knot reduce the strength of a fibre rope?

A
  • up to 50%
79
Q

Calculate the SWL for the following basket hitch:

1/2” diameter wire rope
L= 4 feet H= 3 feet

A

= SWL(1) X (H/L) X 2

SWL(1) = 3/8” + 1/8” = 2 ton = 4000lbf

= 4000lbf X (3/4) X 2

SWL = 6000 lbf

80
Q

Calculate the SWL for a 3/4” single wire rope choker with and angle greater than 45 degrees

A

= SWL(1) X (3/4)

SWL(1) = 3/8” + 1/8” + 1/8” + 1/8” = 4 ton = 8000lbf

SWL = 8000lbf X (3/4) = 6000lbf

81
Q

Calculate the SWL for a 1/2” single wire rope with a choker angle less than 45 degrees and the following dimensions:

A= 1 foot
B= 3 feet
L= 4 feet
H= 3 feet
A

= SWL(1) X (A/B) X (H/L) X 2

SWL(1) = 3/8” + 1/8” = 2 ton = 4000lbf

= 4000lbf X (1/3) X (3/4) X 2

SWL = 2000lbf

82
Q

Calculate the approximate weight of a pile of lumber:

2 foot x 3 feet x 10 feet

A
  • 1 cubic foot of wood = 35lbf

= 2’ X 3’ X 10’ = 60 cubic feet
= 60 cubic feet X 35lbf = 2100 lbs

83
Q

What is the purpose of a block?

A
  • used to lift heavy loads using a small amount of effort

- the ratio of load to effort is called the “Mechanical Advantage” of the block

84
Q

Describe the construction of fibre-rope blocks

A
  • the essential parts of any block are:
    • shell
    • sheaves (cast-iron or cast-steel)
    • centre pin (sheave pin)
    • straps
    • becket
  • fibre-rope blocks the sheaves are normally cast iron
  • NEVER run fibre ropes over sheaves that have been used with wire ropes - rapid rope damage will result
85
Q

What does the term standing block refer to?

A
  • a block that is fixed to a stationary object

- the object takes the force of the loading

86
Q

Compare crane-and-hook blocks to wire-rope blocks

A
  • crane-and-hook blocks are equipped with heavy iron cheek weights
  • wire-rope blocks are normally much lighter
  • wire-rope blocks are not intended to withstand the heavy service and abuse expected of the crane and hook blocks
  • bother suited to high speed applications and heavy loads
87
Q

What do the terms tackle block and snatch block refer to?

A
  • Tackle Block
    • used in conjunction with fibre ropes, both natural and synthetic
    • similar to wire-rope, but lighter and less capacity
    • sheaves in the block should be the proper size for rope being used and must be free and well lubricated
  • Snatch Block
    • can be a single- or multiple-sheave block
    • opens on one side to permit the rope to be slipped over the sheave so it does not have to be threaded through the block
    • normally used when it is necessary to change the direction of the pull on a line
88
Q

How does the angle between lines on a block, secured to an anchor, affect the force in both the hook and the anchor?

A
  • as the direction changes, the angle between the lines increases, the stress on the block and hook is reduced
89
Q

List the for types of chain hoists

A
  • spur-geared
  • screw-geared
  • differential
  • pull-lift (primarily for pulling in horizontal direction)
90
Q

What is the weakest part of a chain hoist?

A
  • all chain hoists are designed with their lower hooks as the weakest parts
  • if the hoist is overloaded it is first indicated by the spreading or opening up of the lower hook
  • DO NOT interchange the two hooks on a chain hoist
91
Q

Describe how the hook and chain are inspected on a chain hoist

A
  • using a set of test gauges
  • load chains
    • check chain link for proper gauge
    • check links for stretch/overloading
  • hooks
    • check opening/throat of hoist hook
    • size stamped on gauge must agree with capacity of the hoist
92
Q

What type of a hoist would be chosen for oily conditions?

A
  • screw-geared

- differential hoist

93
Q

What should be considered before moving a load?

A
  • the characteristics: weight, shape, centre of gravity, overall dimensions
  • present location
  • location it will be moved to
  • equipment available to help move load
  • safety precautions required for move
  • path of the move
94
Q

How do the hoist operator and rigger communicate?

A
  • hand signals

- if the signaller and hoisting-equipment operator cannot see each other, a relay person or a two-way radio may be used

95
Q

What organizations set the rules for hoisting and moving objects?

A
  • WCB

Millwright Manual (24 decks)

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