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"Forces" refer to the physical results and consequences of rigging systems. The forces generated by the use of different systems must be evaluated and considered carefully for each job to prevent the possibility of catastrophic failure within the entire system or individual components. There are several different forces to consider in your work.
2 to 1 force factor at 180 degrees -
This force is present when a rope travels vertically up through a block and then down to the load and anchor or controller. Both parts of the line will experience approximately the force of the load itself, while the block or branch attachment will see twice that load.
1 to 1 force factor at 120 degrees -
Change the angle of the parts of the rope and you can reduce the amount of force generated at various rigging points. At an angle of 120 degrees, the forces on the rigging point and both parts of rope will all be equal.
Bending moments -
To be avoided! These are created when a load or force is put on a rigging or redirect point at an extreme angle. This force can cause the stem or spar to bend with extreme forces present at its base, which may lead to partial or complete failure.
Static loads -
These are loads where there is little, if any, force generated beyond the weight of the piece itself. The rigging point is typically directly above the piece to be rigged, and experiences only the forces required to lower, lift or otherwise maneuver the piece.
Dynamic loads -
Loads where additional force, often a great deal of additional force, is created at the rigging point or within the rigging system by the piece dropping into the system are called dynamic loads. This additional force is generated by the mass of the piece falling into the system under the influence of gravity. The further the piece falls before being caught by the rigging system, the greater the force generated and experienced by the rigging point and system. Dynamic loads are most often generated when the rigging point is below the piece to be removed.
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