Roof Trusses Knuckle crane reaching under tree to pick roof trusses. Crane lifting a large roof truss into place. Knuckle cranes can reach in close to pickup roof trusses, reducing the amount of swinging around in the air. Lifting roof trusses onto roof of home. Knuckle crane lifting prefabricated roof trusses into place on a home. Lifting roof trusses onto roof. Knuckle cranes can work in very tight spaces and can reduce the amount of swinging for a safer and more controlled lift. Moving, sorting and placing roof trusses into place on roof. Crane lifting roof trusses onto home.