HG 85 - Wikipedia

The design of the grenade was made by the federal Munitionsfabrik Altdorf (MF+A) which became SM Schweizerische Munitionsfabrik and later RUAG Ammotech.

The initial detonator was supplied by Diehl (Germany) and later on manufactured under licence in Switzerland. The explosive was supplied from Germany.[3]

The grenade is spherical with a bushing on the top threaded internally to accept the DM 82 CH fuze mechanism.[4] Due to its specially constructed fuze and packaging, the grenade is considered very secure.

On detonation, the steel body containing 155 g (5.5 oz) of TNT releases around 1,800 fragments, weighing on average 0.1 g (0.0035 oz).

A supplementary spring steel safety clip is clipped over the safety lever and bushing on top of the grenade preventing the safety lever from moving.

Operation

Live version

Once the HG 85's safety pin is pulled the grenade is armed, but so long as the fly-off lever is kept depressed while the grenade is held (and the grenade can be held indefinitely with the pin out) it can be safely returned to storage so long as the fly-off safety lever is still in the closed position and the safety pin reinserted.

However, if thrown – or the lever allowed to rise – the protective plastic cover falls away and the striker, under pressure of the striker spring, begins to rotate on its axis. This causes the safety lever to be thrown clear, the striker continues to rotate until it hits the percussion cap, which fires and ignites the delay pellet.

The heat of the burning delay pellet melts solder holding a retaining ring, allowing the detonator to move under the influence of a spring from the safe to armed position. The delay pellet continues to burn and after between 3 and 4 seconds burns out and produces a flash that forces aside a flap valve allowing ignition.

When the flash reaches the detonator this initiates a booster charge which in turn initiates the main explosive filling.

Training versions

The fuze mechanism in the L110A1, under the plastic cover is very similar in appearance to the American fuze mechanisms. Internally there is an extension on the striker to allow it to be re-cocked during training and there is a leaf spring safety that clips around the safety lever and neck of the grenade preventing the lever from rotating even if the safety pin is pulled.

Consisting of two parts, a grey reusable striker mechanism and an L162 practice fuse (which has a blue body with a brown base and is fitted with a silver washer) the L111A1's practice fuse is fitted into the bottom of the reusable striker mechanism then the entire assembly is screwed into the top of the grenade. In this version the safety lever is attached by a plastic strap to prevent loss, the entire unit, apart from the expended L162 practice fuse, being reused.