Sentence:  Hauler, noun./ "Then, holding myself in position by grasping the part of the rope that falls from the other side of the fork, I unclip the loop round the trunk and let it swing clear. Next, combining the roles of <WSD>hauler</WSD> and haulee, I climb up, hand over hand using irons as much as possible, until I am right under one of the dividing limbs of the fork." 
Meaning of the word marked with <WSD> tags:  A person or thing that hauls another person or thing.