Mechanical advantage and stress

a. What is meant when a tackle is said to be roved to advantage?It means that the same block and tackle has an extra Mechanical advantage than if it had been rigged to disadvantage.

b. How can you determine if a tackle is rigged to advantage?It is rigged so that the hauling part is leading from the moving block

c. How can you determine if a tackle is rigged to disadvantage?It is rigged so that the hauling part is leading from the standing block

d. How can you determine the mechanical advantage of a block and tackleBy counting the number of lines connected to the moving block

e. What is the mechanical advantage of a gun tackle that is roved to advantage? MA=3

f. What is the MA of a three fold purchase that is roved to disadvantage? MA=6

g. When calculating the stress on the hauling part. How much extra stress must be taken into account for friction?10% of the weight per sheave

h. What is meant by velocity ratio?VR is directly connected to MA and is the amount of line that has to be hauled to move the load a particular distance. For instance, with a tackle that has an MA of 4, the VR is 4:1, that is four meters of line has to be hauled to move the load 1 meter