What is the precise definition of 'zero mechanical state' in the context of Lockout/Tagout procedures?

In the context of Lockout/Tagout (LOTO) procedures, 'zero mechanical state' is the condition of equipment where all potential mechanical energy sources are safely dissipated, blocked, or relieved, preventing any unexpected movement or hazardous release of energy. This means that all moving parts are at rest, any springs are de-tensioned or restrained, elevated components are lowered and secured, and any other potential sources of mechanical energy, such as gravity or stored momentum, are neutralized. Achieving zero mechanical state involves more than simply turning off the equipment's power switch. It requires a systematic process of identifying all mechanical energy sources, applying appropriate lockout devices (such as locks, chains, or tags) to prevent the energy sources from being reactivated, and verifying that the equipment is indeed in a zero-energy state before any maintenance or repair work begins. For example, on a hydraulic press, achieving zero mechanical state would involve not only disconnecting the power supply but also bleeding off any residual hydraulic pressure, blocking the ram to prevent it from falling, and verifying that the ram cannot move. Similarly, on a vehicle, it would mean applying the parking brake, chocking the wheels, and, if necessary, using additional supports to prevent movement. Verification is a crucial step, involving attempting to operate the equipment controls to confirm that it remains in a safe, non-operational state.