To complete the Underworld Gate tomb in the Peruvian Jungle in Shadow of the Tomb Raider turn the pillar so that the rope wrapped beam faces to the left. Use a rope arrow to make a path to the cliffs ahead and go to the cliffs. Use the wooden beam to move the crane backwards. Go back to the pillar at the start and turn it back the other way. Use a rope arrow to attach the weight to the rope wrapped beam and jump over to the weight and back over to the bottom of the crane. Move the crane back to its original position and quickly jump back over to the weight. On the other side go through the area and climb up to the end of the Underworld Gate tomb. .

As found on Youtube