What is Mechanical Advantage?
The ratio of the output force (acting on a load) produced by a mechanism to the applied effort (the input force). Measure of the force amplification achieved by using a tool, mechanical device or machine system.
What are the 6 basic elements of a mechanism?
- Lever
- Wheel and Axle
- Pulley
- Inclined Plane
- Wedge
- Screw
What is the Safety Factor?
A ratio used to identify the maximum allowable weight for the load to be lifted, or the Working Load Limit.
How do you find the Safety Factor?
Safety Factor = Breaking Strength / WLL
What are the basic tools and equipment used when rigging?
- Hooks and Shackles
- Handlines
- Blocks
- Hoists
- Snubbing Chains
- Slings
What are the 3 components of a hook?
- Throat Opening for placing the load of an eye
- Eye for rigging a line to
- Hook Latch for keeping the load safely on the hook
What are the guidelines for using hooks in rigging?
- Be sure all hooks (except grab hooks and sorting hooks) are equipped with safety catches
- If a hook cannot be safely used, replace it with a shackle
- If you are attaching more than one sling to a hook, use a bolted shackle to keep the hook from spreading
- Never insert the point of a hook in an eye bolt, use a shackle
- Whenever a load passes over employees and hooks are used to attach the load, a safety-type hook, latch, or equivalent shall be used.
What are the inspection points of a hook?
- Wear in the saddle of the hook not to exceed 10% of original dimension
- Cracks, severe corrosion, severe nicks or gouges, any other signs of fatigue
- Proper latch operation
- Distortion including twisting, hooks spreading “throat opening” and hook elongation caused by stretching
What is a shackle?
U-Shaped fitting with a pin usually used on conjunction with a hook.
What are the two common types of shackles commonly used in rigging?
- Anchor (bow type)
- Chain (“D” type)
What must a shackle have on it in order to be used?
The WLL must be stamped onto it.
What is a handline made up of?
1/2” polyester-polypropylene synthetic rope with a WLL of 700lbs
When working on a tower, what must be attached to a handlines?
A Chain Becky.
What is a hoist used for and how?
Used for pulling, stretching and lifting. They use a chain, or strap and are mechanically operated as opposed to human force.
What are the two types of hoists used by lineman?
- Lever Ratchet Hoists
- Web Strap Hoists
What is another name for a Snubbing Chain? And what is it used for?
Dumb Grunt. A tie-down point during rigging on a pole. The Snubbing Chain provides an anchoring point for various types of rigging.
What are Wire Pulling Socks used for?
To pull conductor across long spans. the Kellum grip is a wire mesh “sock” that tightens on to the conductor end that ensures a firm grip on the conductor.
When is a Capstan used?
To gain mechanical advantage when objects or equipment is too large or heavy for people to lift or carry safely.
