Trucker's hitch advantage would be only 2:1. However in the common use of the trucker's hitch, a static hook, ring, or rail, serves as the lower pulley, and the rope across the top of the load is the portion being tensioned. Thus, the standing part of the rope is represented by the top anchor point in the diagram, and the theoretical ratio is indeed 3:1 when the working end is tensioned. That is, in a frictionless system, every unit of force exerted on the working end would produce 3 units in the standing part of the rope over the load. In the
Block and tackle each of the parts of the rope must be "F/n." This means the input force on the rope is "F"="F/n." Thus, the block and tackle reduces the input force by the factor "n." Ideal mechanical advantage correlates directly with velocity ratio. The velocity ratio of a tackle is the ratio between the velocity of the hauling line to that of the hauled load. A line with a mechanical advantage of 4 has a velocity ratio of 4:1. In other words, to raise a load at 1 metre per second, the hauling part of the rope must be pulled at 4