Use and Operation of Blocks Flashcards
In the picture, the mechanical advantage is ? .
1
In the picture, the mechanical advantage is ? .
2
The constant force applied to an object to keep that object in place is ? force.
Static
As a rule of thumb, the friction loss for each sheave is approximately ? of the sheave load.
10%
As the angle between the load line and the lead line (fall line) increases, the load of the block ? .
decreases
A ? block is the lower movable block in a block and tackle configuration.
Traveling
A single block hoisting assembly has a fall line pull of 150 pounds. If the lines are parallel to each other and ignoring friction, the load on the block will be ? .
300lbs =150lb on pull line + 150lb load
As more sheaves reduce the force required to lift a load, the distance the lead line must be pulled decreases.
False
It increases
The force of two objects resisting movement is ? .
Friction
Mechanical advantage means that a load can be lifted by applying a force more than the load weight.
False
A sheave is a grooved wheel attached to a frame that supports a rope that is changing directions.
True
Before a new wire rope is threaded over a block sheave, a Qualified Electrical Worker should check ? .
that the contour of the sheave matches the rope size
The lead line is the part of the rope to which force is applied to hold or move a load.
true
When lifting a load with a block and tackle system, part of the lifting force is lost due to ? in the turning of the sheaves.
friction
Lacing is the simplest method of reeving
true
