Chapter 9 Flashcards
Snatch Blocks
Why are Snatch Blocks used?
To redirect a rope in may different rigging situations.
When are Snatch Blocks commonly used?
When performing work on transmission lines.
What can Snatch Blocks also reduce?
Haul Line Tensions in some rigging configurations.
What is the unique feature of a Snatch Block?
It can open near the swivel to trap the bight of the rope
What are the components that make up a Snatch Block?
- Hook
- Safety Latch
- Pivot Pin
- Locking Pin
- Shell
- Center Pin
- Sheave
What should you do before using a Snatch Block?
Read the manufacturer’s recommended care and inspection criteria.
When inspecting the Hook & Safety Latch what are you looking for?
- Bent Hook
- Defective Safety Latch
- Excessive wear at all contact points
- Metal Fatigue
When inspecting the Locking Pin, Pivot Pin and 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?
Seated & Secured Tightly
When inspecting the Sheave 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 Snatch Blocks have their Weight Rating?
Stamped on the hook or shell
What should you do with a Snatch Block if it doesn’t have a weight rating tag visible?
Remove it from service immediately.
What should you always do before using blocks in a rigging application?
Read the weight rating and calculate the tensions involved.
How should you store blocks?
In a dry place.
What should you do if blocks become soiled?
Rinse thoroughly and lubricate the sheave bearing per the manufacturer’s recommendations.
What is the tension placed on a Snatch Block dependent on?
The angle that the rope is passing through the block.
What happens when the angle decreases?
The tension on the block increases.
What does this tension affect?
Sling and point of attachment.
What happens to the rope when it is passed through the block?
Friction is created.
What is this amount of friction dependent on?
The angle that the rope passes through the block
What is the standard amount of friction?
10%
Where is the friction applied?
To the Line Out
When the friction to the Line Out, how does it compare to the Line In?
Line out has 10% more than Line In
What is the equation for Snatch Block Tension?
Snatch Block Tension = Line Out x Angle Factor
Line Out of the first block is what to the second block?
Line In
What does the tension of a block determine?
- Size of the Block
- Size of the Sling its attached to
- Size of the Anchor Point
