BLOCKING (EN: blocking; DE: Blockieren, Verriegelung; FR: blocage; ES: bloqueado; RU: блокировка) is the combination of the methods and means, which are ensuring the fixation of the working parts (elements) of the apparatus, machine, or electrical circuit in the determined position (status), which is preserved independently of the fact, whether the blocking impact has been eliminated or not.

Blocking improves the safety of the servicing and the reliability of the working of the equipment, ensures the required sequence of the switching-on for the mechanisms and elements of the devices, and also the limitation of the movements of the mechanisms within the limits of the working zone. The position (status) of the working parts of the object, depending on the principle of operation of the blocking device, is being fixated with the help of the mechanical, magnetic, optical, or electrical connections. Blocking is being terminated by the impact, in case of which the blocked parts of the apparatus, machine, or electrical circuit return into the initial status (before the blocking), or there is permitted the transition into another working position in case of the availability of the corresponding signal. They perform the blocking manually, semi-automatically, or automatically (self-blocking). The blocking within the electrical devices, in case of the wrong actions during their switching-on, provides the disconnection of the electrical circuit.

They widely use the blocking within the mining industry. The mechanical blocking of the covers of the equipment, contactors, and other devices of the mine and petroleum extracting automation, which is produced according to the explosion-proof design, ensures the protection of the servicing personnel during the inspections and repairs, preventing the opening of the casing during the presence of the voltage within the chambers of the apparatus. They use the electrical blocking at the underground mine and open pit mine transport for the safety of the movement of the trains, and for the increasing of the throughput capability of the haulage routes; at the human and skip hoists, for the ensuring of the specified cycle for the movement of the lifting vessel, and for the prohibition of the subsequent start, in case of the violations of the working of the individual parts of the system (heating of the bearings, absence of lubrication, decreasing of the resistance of the electrical insulation, and so on); within the systems for the control of the mining machines for the prevention of accidents.