319. A sinking crosshead shall:(1) have a safety device designed to hold back the bucket when the sinking crosshead is stuck;
(2) be designed to prevent the bucket connected to it from swinging;
(3) when it is used to raise or lower persons, be equipped with a protective roof made of sheet steel having a thickness of at least 4 mm (0.2 in) or a material having equivalent strength;
(4) designed so that the opening of its lower part is circular to enable the bucket to fit into it.