Charles Ragon de Bange - Career - de Bange Breech Obturator System

De Bange Breech Obturator System

Many attempts had been made at developing breech-loading cannons, but had only partial success sealing of the breech. When fired, hot gasses and burning gunpowder could escape, losing power and potentially burning the operating crew. Rifles, with smaller loads and less stress, were able to use rubber or other materials in O-rings, but a suitable system for cannons was not as easy to come by. Several materials were able to hold the pressure and heat of cannon fire, but did not naturally expand like rubber, thereby failing to provide a tight seal.

In 1872, de Bange designed the De Bange system, a new type of obturator for cannons. His design used a breech block made of three parts; an interrupted screw locking mechanism at the rear, a doughnut-shaped grease-impregnated asbestos pad that sealed the breech, and a rounded movable "nose cone" at the front. When fired, the nose was driven rearward, compressing the asbestos pad, squeezing it so it expanded outward to seal the breech. The French referred to the shape of the breech's nose as "mushroom like", as it resembled the cap of a mushroom.

The action was controlled by a handle, normally mounted vertically on the right side of the breech. When lifted, the handle operated a cam that forced the breech to rotate counter-clockwise, unlocking the interrupted thread. The entire breech was then pulled rearward with the same handle, sliding on a ring-shaped holder. The breech holder was hinged on one side, normally the left, so when the breech block was slid all the way to the rear it could be rotated out of the way for loading.

The de Bange system was widely adopted, including by the United States Navy and the British Royal Navy. The technique developed by de Bange is still in use today.

The only major advance on the original de Bange system was the introduction of the stepped screw in the Welin breech block of 1889, which greatly increased the load-bearing surface of the breech, allowing them to be made shorter, simpler, more secure and faster to operate. Other block mechanisms are also used, but the de Bange obturator remains widespread even on these.