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The Welin breech block was a revolutionary stepped, interrupted thread design for locking artillery breeches, invented by Axel Welin in 1889 or 1890. Shortly after, Vickers acquired the British patents. Welin breech blocks provide obturation for artillery pieces which use separate loading bagged charges and projectiles. In this system the projectile is loaded first and then followed by cloth bags of propellant.
The breech block screw incorporates multiple threaded "steppings" of progressively larger radius and a gap step occupying each circular section. A three step breech block screw's circular area would nominally be divided into quarters, with each quarter containing three threaded sections of progressively increasing height and a gap step for insertion.
Each step engages with its matching thread cut in the gun breech when inserted and rotated. A gap in the thread steps was still necessary for the insertion of the largest step before rotation, so the area of the breech secured by threads in the block is:
This was a major improvement on previous, non-stepped designs such as the de Bange system. The breech loader [of the] de Bange system uses a single thread step and can only engage half of the block's circumferential threads with the breech, necessitating a long screw to achieve a strong lock. Efficiency is gained with multiple thread step heights on an interrupted screw because the smaller thread steps may be inserted into the breech along the radial vector of any larger step, whereas a single thread step interrupted screw cannot be inserted where any threads of the breech lay in the radial vector as any threads of the screw. Thread lock area is directly related to the munitions strength which may be safely fired, and thus large munitions with single step screw breeches needed unreasonably long breech screws. These in turn required more time and much greater room to extract and move aside to gain access the gun's chamber to clean and reload it. The engagement of threads around much more of the circumference of the Welin block allowed it to be shorter for the same total engagement area and strength, it required less than 90 degree rotation to lock the threads, making operation faster than previous designs and possible in much tighter space. [1] It was also simpler and more secure.
The Welin breech was a single motion screw, allowing it to be operated much faster than previous interrupted-thread breeches,[ citation needed ] and it became very common on British and American large calibre naval artillery and also field artillery above about 4.5 inches (114 mm).[ citation needed ]
Though the US Navy was offered the design a year or two after its invention, they declined and the American Bethlehem Steel spent the next five years in trying to circumvent Welin's patent, before having to buy it through Vickers.[ citation needed ]
The 16"/50 caliber Mark 7 – United States Naval Gun is the main armament of the Iowa-class battleships and was the planned main armament of the cancelled Montana-class battleship.
A shell, in a military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military context. Modern usage sometimes includes large solid kinetic projectiles, which are more properly termed shot. Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used.
A breechloader is a firearm in which the user loads the ammunition via the rear (breech) end of its barrel, as opposed to a muzzleloader, which loads ammunition via the front (muzzle).
A rifled breech loader (RBL) is an artillery piece which, unlike the smoothbore cannon and rifled muzzle loader (RML) which preceded it, has rifling in the barrel and is loaded from the breech at the rear of the gun.
A breechblock is the part of the firearm action that closes the breech of a breech loading weapon before or at the moment of firing. It seals the breech and contains the pressure generated by the ignited propellant. Retracting the breechblock allows the chamber to be loaded with a cartridge.
This article explains terms used for the British Armed Forces' ordnance (weapons) and ammunition. The terms may have slightly different meanings in the military of other countries.
An interrupted screw or interrupted thread is a mechanical device typically used in the breech of artillery guns. It is believed to have been invented in 1845.
The Armstrong RBL 7-inch gun, also known as the 110-pounder, was an early attempt to use William Armstrong's new and innovative rifled breechloading mechanism for heavy rifled guns.
A muzzle-loading rifle is a muzzle-loaded small arm or artillery piece that has a rifled barrel rather than a smoothbore. The term "rifled muzzle loader" typically is used to describe a type of artillery piece, although it is technically accurate for small arms as well. A shoulder arm is typically just called a "rifle", as almost all small arms were rifled by the time breechloading became prevalent. Muzzle and breechloading artillery served together for several decades, making a clear distinction more important. In the case of artillery, the abbreviation "RML" is often prefixed to the guns designation; a Rifled breech loader would be "RBL", or often just "BL", since smoothbore breechloading artillery is almost nonexistent. A muzzle loading weapon is loaded through the muzzle, or front of the barrel. This is the opposite of a breech-loading weapon or rifled breechloader (RBL), which is loaded from the breech-end of the barrel. The rifling grooves cut on the inside of the barrel cause the projectile to spin rapidly in flight, giving it greater stability and hence range and accuracy than smoothbore guns. Hand held rifles were well-developed by the 1740s. A popularly recognizable form of the "muzzleloader" is the Kentucky Rifle, which was actually developed in Pennsylvania. The American Longrifle evolved from the German "Jäger" rifle.
An Armstrong gun was a uniquely designed type of rifled breech-loading field and heavy gun designed by Sir William Armstrong and manufactured in England beginning in 1855 by the Elswick Ordnance Company and the Royal Arsenal at Woolwich. Such guns involved a built-up gun construction system of a wrought-iron tube surrounded by a number of wrought-iron strengthening coils shrunk over the inner tube to keep it under compression.
The British BL 6-inch gun Mk XIX was introduced in 1916 as a lighter and longer-range field gun replacement for the obsolescent BL 6-inch gun Mk VII.
The QF 3-inch 20 cwt anti-aircraft gun became the standard anti-aircraft gun used in the home defence of the United Kingdom against German Zeppelins airships and bombers and on the Western Front in World War I. It was also common on British warships in World War I and submarines in World War II. 20 cwt referred to the weight of the barrel and breech, to differentiate it from other 3-inch guns. While other AA guns also had a bore of 3 inches (76 mm), the term 3-inch was only ever used to identify this gun in the World War I era, and hence this is what writers are usually referring to by 3-inch AA gun.
The BL 13.5 inch naval gun Mk I was Britain's first successful large breechloading naval gun, initially designed in the early 1880s and eventually deployed in the late 1880s. Mks I - IV were all of 30 calibres length and of similar construction and performance.
The BL 9.2-inch Mk IX and Mk X guns were British breech loading 9.2-inch (234 mm) guns of 46.7 calibre, in service from 1899 to the 1950s as naval and coast defence guns. They had possibly the longest, most varied and successful service history of any British heavy ordnance.
Charles Ragon de Bange was a French artillery officer and Polytechnician. He invented the first effective obturator system for breech-loading artillery, which remains in use. He also designed a system of field guns of various calibers which served the French Army well into World War I: the Système de Bange.
The Reffye 85 mm cannon was a French artillery piece of the 19th century, developed by the French artillery General Jean-Baptiste Verchère de Reffye, superintendent of the works at Meudon. The weapon was adopted by the French Army from 1870. It was an 85 mm (3.35-inch) rifled breech-loading cannon, equipped with a breech screw, initially made of bronze.
The Reffye 75mm cannon was a French artillery piece of the 19th century, developed by the French artillery General Jean-Baptiste Verchère de Reffye, superintendent of the works at Meudon. The weapon was adopted by the French Army from 1873. It was a 75 mm rifled breech-loading cannon, equipped with a breech screw, initially made of bronze.
The 14"/50 caliber gun was a naval gun mounted on New Mexico and Tennessee-class battleships. These ships also featured the first "three-gun" turrets, meaning that each gun in each turret could be "individually sleeved" to elevate separately. The 14"/50 caliber guns were designated as Mark 4 and 6, with later versions known as Mark 7, 11, and B. These guns were more powerful than the main gun mounted on the previous three classes of US battleships, the 14"/45 caliber gun.
An Asbury Mechanism opens and closes the breech of heavy artillery for reloading with a projectile and bags of propellant. It was widely used for naval artillery of the world wars and similar coastal artillery and railway guns. The device was invented at the Washington Navy Yard in 1916 by draftsman Dorsey Frost Asbury. It is sometimes called a Smith-Asbury mechanism by the United States Navy in recognition of Asbury's supervisor, Lieutenant Commander George Leonard Smith, USN.
The Obice da 280 was an Italian coastal defense and siege howitzer designed in 1884 by the British Armstrong firm and produced under license by the Ansaldo company during the late 1800s. It was used during both the First and Second World Wars.
