Chapter 8 Flashcards
Parted Blocks
When are Parted Blocks commonly used?
- Sag Conductors
- Set Poles
- Hang Pole Line Equipment
When is Pole Setting and Equipment Installation usually done with blocks?
When the location is inaccessible to derricks and material handlers.
What are the components that make up Parted Blocks?
- Hook
- Safety Latch
- Swivel
- Sheaves
- Shell
- Center Pin
- Becket
When inspecting the Hook & Safety Latch what are you looking for?
- Bent Hook
- Defective Safety Latch
- Excessive Wear at ALL Contact Points
- Metal Fatigue
- Rust
When inspecting the Swivel what are you looking for?
- Metal Fatigue
- Rust
- Excessive Wear
- Operates freely
- Lubricate if Needed
When inspecting the Shell what are you looking for?
- Cracks
- Breaks
- Sharp Edges
When inspecting the Center Pin what are you looking for?
Tightly Seated & Secured
When inspecting the Becket what are you looking for?
- Secure
- Check for wear on the rope at the point of contact
When inspecting the Sheaves what are you looking for?
- Turns Freely
- Excessive wear on the bearings by moving the sheave up & down
- Cracks & sharp edges that can cut the rope
Where will blocks typically have their weight rating?
Stamped on the hook or shell
If a block doesn’t have its weight rating tag visible what should you do?
Remove it from service immediately.
What should you do before using parted blocks?
Ensure that the proper blocks are used for the rigging application.
Where should you store Parted Blocks?
In a dry place.
What should you do if Parted Blocks become soiled?
Rinse thoroughly and lubricate the sheave bearings per the manufacturer’s recommendations.
What is the point of Parted Blocks?
To provide a Mechanical Advantage.
How is the advantage of Parted Blocks provided?
Because there are multiple parts of rope supporting the load.
How is the load divided when using parted blocks?
Between the number of parts supporting it
What are the two tensions involved with Parted Blocks that care critical for lineworkers to understand?
- ) Haul Line
2. ) Hook Strain
Why is Haul Line calculated?
- To verify that the WLL of the rope is not exceeded.
- To determine that the WLL of the hoisting mechanism is not exceeded
Why is Hook Strain calculated?
To verify that the WLL of the blocks is not exceeded.
What happens when a rope travels through a sheave?
Friction is created.
What does the friction create on the rope?
TENSION
What is a good rule of thumb when calculating the friction on a rope running through a sheave?
10%
Is there Mechanical Advantage when only one block is used?
NO
When is one block ONLY used?
When the direction of pull must be changed or an object must be raised.
What does the number of parts supporting the load determine?
The amount of Mechanical Advantage gained.
When does the friction overcome the Mechanical Advantage?
When 10 or more parts of rope are used
What is the equation of the Haul Line?
1.1p x W / P
When does the greatest Mechanical Advantage occur?
At TWO Parts
After how many parts does the Haul Tensions Line begin to decrease?
After 10 parts
When is the Haul Tension Line greater than the load?
When only ONE part is used.
What should you notice when increasing the number of parts increases?
The tension on the haul line decreases.
What are the two forces that apply tension to the hook?
- The weight of the load
- Force applied to the haul line
What is the Hook Strain equivalent to?
Haul Line Tension PLUS the weight of the load.
Why is Hook Strain calculated?
To ensure that the WLL o the block is not exceeded.
Which is greater the Standing Block Hook Strain or the Running Block Hook Strain?
Standing Block Hook Strain
What is the equation to calculate Hook Strain?
Haul Line + W
(1.1p x W / P) + W
What happens to Hook Strain when # of Parts is Increased?
It decreases.
Why is it important to calculate hook strain before any rigging application?
To ensure the proper selection of equipment.
