Nó carioca duplo/nó de caminhoneiro duplo

The double trucker's knot (also known as a traction knot or other knot) is very useful when you need to pull a rope or even secure loads, but at certain times you need more force to pull the rope, since simple traction was not enough. The double knot increases the mechanical advantage by 9x, allowing a single person to exert the force of 9 men.