Boom free fall: live boom equipment (a boom built to free fall) may not be used when anyone is inside the boom's or load's fall zone, when an employee is being hoisted, when the boom or load is right above a power line or above the strip reaching the Table A distance either side of it, or that strip lies inside the vertical travel radius of the boom or load, when the load is over a shaft with employees in it, when the load is over a cofferdam with employees in the fall zone, or during lifting in a refinery or tank farm. Even where none of those conditions exists, live boom equipment may be used only if made before October 31, 1984, or if it is a floating crane or derrick or a land crane or derrick on a vessel or flotation device. Where live booms are prohibited, the boom hoist needs a secondary device that stops the boom falling if the primary holding system fails: friction drums need a friction clutch plus a braking device for controlled lowering, and a secondary brake or locking device (for instance a ratchet-and-pawl set or an additional friction brake), engaged manually or automatically, that backs up the main brake whenever the boom is being held; hydraulic drums need an internal static brake or a holding device mounted integrally; clutches and hydraulic motors do not count as brakes or locks; hydraulic boom cylinders need integrally mounted holding devices. Hydraulic telescoping booms need an integral holding device to stop retraction on hydraulic failure. Load line free fall is prohibited, and controlled load lowering (using the hoist drive, not just the brake) is required, when someone is directly beneath the load, a worker is being hoisted, the load is over a power line or its Table A band (or the band is within the load's vertical travel radius), the load is over a shaft, or the load is over a cofferdam with employees in the load's fall zone.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.