screwman

noun
screw·​man | \ -ümən\
plural screwmen

Definition of screwman

1 : one who passes metal through a rolling mill and reduces it to desired thickness by adjusting screws that regulate roller clearance
2 : one who helps to prepare the way for and to set up power shovels and cranes

called also jackman

3 : one who loads bales of cotton onto a riverboat