Model or a Mastery Sheer. Model of a mast crane, a mast lifting, on base plank. The legs lean forward and are retained by two crowds and four stains of bolders confirmed. The foot in which the crowd is adjustable in two positions. Behind the bollards are two capstan and two beting. There is a major predict between the paws of the mast crane. Two hoists, one for the top and one for the lower part of the mast: the rope is attached at the top of the mast valve and is hence through the double block that is attached to the mast and a three-disc block at the top of the mast crane, then To a block to the pay, back to the three-disc block at the top and down. At the top of the mast are two more blocks with rope, which is attached to the beting with both ends.