VZD-20M

Designed to detonate explosive charges (engineering mines) after a preset delay time. The VZD-20M detonator is mainly used for detonating sticky SPM, UPM mines and explosive charges at depths of up to 40 m.

It consists of a case, a clockwork mechanism, a mechanism for setting the delay time, starting, striking and triggering mechanisms, a pin-ignition device and a fuse (special or MD-5M). The case serves to accommodate the fuse mechanisms. A scale with numbers indicating the delay time in hours is applied to the cylindrical surface of the case. To ensure the possibility of setting the desired delay time in conditions of lack of visibility, there is a protrusion on the case opposite the zero division of the scale. The clockwork, striking and triggering mechanisms are similar to those used in the VZD-144 detonator. The mechanism for setting the delay time consists of two disks - the setting and safety disks, fixed on the sleeve, and a handle. The sleeve is mounted on the winding axis. The setting disk is fixed to the sleeve immovably. It has 11 grooves corresponding to the delay times indicated on the scale. The safety disc has one groove and can rotate counterclockwise with the handle. The delay time is set by aligning the groove of the safety disc with the corresponding groove of the setting one. The curved end of the trigger lever rests on the surface of both discs, which slides along them during the setting of the delay time and the operation of the clockwork. When the clockwork is operating, the winding axis together with the discs makes one full revolution in 24 hours. After the set time has elapsed, the end of the trigger lever falls into the aligned grooves, and the fuse is triggered. There is an indicator line on the handle. Its position is fixed by a spring ball stopper that enters the handle slots. The direction of rotation of the handle is indicated by an arrow. Reverse rotation is blocked by latches. The trigger mechanism consists of a spring slider, a trigger check and a spring stopper. The stopper rests against the slider and holds the wound balance of the clockwork. The slider is held in the transport position by a trigger check, fixed by a bracket worn on the protrusion of the housing. When the check is pulled out, the slider moves under the action of a spring, the hole in the slider aligns with the stopper, the latter enters it and releases the balance. The ignition device consists of a primer-igniter, an amplifier, a sleeve with a striker fixed by a shear check. The amplifier and the sleeve with the striker are placed in the sleeve, which is screwed into the fuse housing. The sleeve has a threaded hole for the fuse, which is closed with a plug. A membrane is provided for sealing. A threaded sleeve is fixed to the sleeve, with the help of which the fuse is attached to the SPM or UPM mine. A special fuse is used with SPM and UPM sticky mines. It consists of a sleeve with a primer-igniter and a primer-detonator No. 8-A, which is fixed in it with epoxy glue. During storage, the primer-igniter is closed with a cap. The sealing of the connection of the fuse with the mine and the detonator is ensured by rubber gaskets. The MD-5M fuse is used with standard explosive charges. VZD-20M detonators are stored with a wound spring and a cocked striker, with the handle set to the zero scale division.

When the trigger check is pulled out, the balance is released and the clockwork mechanism starts. During its operation, the setting and safety discs rotate. After the set delay time has elapsed, the aligned grooves of the discs approach the end of the trigger lever. Under the action of the spring, the lever falls into these pairs, its axis rotates and releases the executive lever. The latter, in turn, releases the striker, which pierces the primer-igniter. The flame from the primer-igniter ignites the amplifier. The gases formed during its combustion push the striker, the shear check collapses, and the striker pierces the fuse screwed into the detonator. An explosion occurs, initiating the detonation of the mine (charge).

To prepare the detonator, you must: Set the desired delay time by turning the handle counterclockwise, aligning the indicator line with the corresponding scale division; Equip the detonator with the appropriate fuse: unscrew the plug and screw the fuse in until it stops (when using the MD-5M fuse, a rubber gasket removed from the plug is put on it). Setting the time in conditions of lack of visibility (at night, under water) can be done by counting the number of clicks of the ball lock when turning the handle counterclockwise. To do this, make sure by touch that the handle is with the line opposite the protrusion on the body (i.e. at the zero scale division), then carefully turn the handle counterclockwise, counting the number of clicks of the lock. Each click corresponds to one scale division, which is equal to two hours of delay. Thus, you can set the required deceleration time even in complete darkness or under water. After setting the required deceleration time and equipping with a fuse, the fuse is ready to be installed in a mine or charge. In the case of use with SPM or UPM mines, the fuse is screwed into the mine socket using a threaded sleeve that is included in the fuse body. When used with standard explosive charges, the MD-5M fuse is screwed in, which ensures the initiation of the charge. Important: the fuse must be installed and equipped immediately before use, observing all safety measures. After pulling out the trigger, the fuse is considered to be in combat condition, and its movement or dismantling is prohibited.

Safety precautions when working with VZD-20M - It is forbidden to pull out the trigger check before the installation preparation is completely completed. - Do not allow the fuse to be hit or dropped. - Do not store equipped fuses near heat sources or open flames. - When using in water, make sure that the connection of the fuse with the fuse body is tight. - After the set delay time has elapsed, even if the explosion has not occurred, it is strictly forbidden to approach the mine or explosive charge - the object is considered dangerous. - Thus, the VZD-20M fuse provides reliable delayed detonation of engineering mines or explosive charges, especially effective in an aquatic environment, due to the tightness of the design and the ability to set the deceleration time without visual control.