Bearings have had a long and complex history, from the first primitive wooden bearing to the modern class of self-lubricating bearings. With continued development in material science and lubricant technology, and steady improvements in manufacturing, the future promises bearings of a more sophisticated design than ever before.

Bore diameterbearing meaning

Gauge is commonly used today in reference to shotguns, though historically it was first used in Musket later on in large double rifles, which were made in sizes up to 2 bore during their heyday in the 1880s, being originally loaded with black powder cartridges. These very large rifles, called "elephant guns", were intended for use primarily in Africa and Asia for hunting large dangerous game.

The table below lists various gauge sizes with weights. The bores marked * are found in punt guns, obsolete, or rare weapons only. However, 4 gauge was sometimes found used in blunderbuss guns made for coach defense and protection against piracy. The .410 and 23 mm are exceptions; they are actual bore sizes, not gauges. If the .410 bore and 23 mm diameters were measured using more traditional means, they would be equivalent to 67.62 gauge (.410 bore) and 6.278 gauge (23 mm), respectively.

Bore diameterformula

An n-gauge diameter means that a ball of lead (density 11.34 g/cm3 or 0.4097 lb/in3) with that diameter has a mass equal to ⁠1/n⁠ part of the mass of the international avoirdupois pound (approx. 454 grams), that is, that n such lead balls could be cast from a pound weight of lead. Therefore, an n-gauge shotgun or n-bore rifle has a bore diameter (in inches) of approximately

Shotgun bores are commonly "overbored" or "backbored", meaning that most of the bore (from the forcing cone to the choke) is slightly larger than the value given by the formula. This is claimed to reduce felt recoil and improve patterning. The recoil reduction is due to the larger bore producing a slower acceleration of the shot, and the patterning improvements are due to the larger muzzle diameter for the same choke constriction, which results in less shot deformation. A 12-gauge shotgun, nominally 18.5 mm (0.73 in), can range from a tight 18 mm (0.71 in) to an extreme overbore of 20 mm (0.79 in). Some also claim an increased velocity with the overbored barrels, up to 15 m/s (49 ft/s), which is due to the larger swept volume of the overbored barrel. Once only found in expensive custom shotguns, overbored barrels are now becoming common in mass-marketed guns. Aftermarket backboring is also commonly done to reduce the weight of the barrel and move the center of mass backward for a better balance. Factory overbored barrels generally are made with a larger outside diameter, and will not have this reduction in weight—though the factory barrels will be tougher, since they have a normal barrel wall thickness.

Firing slugs from overbored barrels can result in very inconsistent accuracy, as the slug may be incapable of obturating to fill the oversized bore.

The 18, 15, 11, 6, 3, and 2 gauge shells are the rarest of all;[6] owners of these types of rare shotguns will usually have their ammunition custom loaded by a specialist in rare and custom bores. The 14 gauge has not been loaded in the United States since the early 20th century, although the 2+9⁄16-inch (65 mm) hull is still made in France.[6] The very small 24 and 32 gauges are still produced and used in some European and South American countries. Punt guns, which use very large shells, are rarely encountered.

Bearingbore diameter

Even before the creation of the wheel at the very beginning of human civilization, the concept of bearings had already taken shape. At that time, people realized that placing rolling logs beneath heavy objects made it easier to drag them across a surface.

How to measurebore diameter

The gauge of firearms is determined by: 1 pound/gauge = weight of lead sphere. Caliber of the bore is then measured.[2][full citation needed]

During the 20th century, improvements in bearings went hand-in-hand with the great advances in the automotive, machine tool and military industries. The choice of rolling elements expanded from balls to rollers, tapered rollers and spherical rollers. Bearings could support greater forces and combined (axial and radial) loads.

Bore diameterof cylinder

It was Sven Winquist who came up with a self-aligning design for ball bearings that set a new standard in terms of design. A quick succession of innovations within the field emerged, from the wire race bearing to the vee groove bearing.

It would be difficult to imagine the modern industrial age without bearings. Every kind of machine that deals will motion makes use of bearings to smoothen its path and reduce friction. Such an important piece of technology did not fall into the laps of engineers when they started creating metal machines, but has a long and storied history of use that stretches all the way back to the stone age.

The chamber of the gun is larger, to accommodate the thickness of the shotshell walls, and a "forcing cone" in front of the chamber reduces the diameter down to the bore diameter. The forcing cone can be as short as a fraction of an inch, or as long as a few inches on some guns. At the muzzle end of the barrel, the choke can constrict the bore even further, so measuring the bore diameter of a shotgun is not a simple process, as it must be done away from either end.

What is bore diameterfirearms

The six most common shotgun gauges, in descending order of size, are the 10 gauge, 12 gauge, 16 gauge, 20 gauge, 28 gauge, and .410 bore.[3] By far the most popular is the 12 gauge,[3] particularly in the United States.[4] The 20-gauge shotgun is the next most popular size, being favored by shooters uncomfortable with the weight and recoil of a 12-gauge gun, and is popular for upland game hunting. The next most popular sizes are the .410 bore and the 28 gauge. The least popular sizes are the 10 gauge and the 16 gauge; while far less common than the other four gauges, they are still commercially available.[citation needed][5]

The gauge (in American English or more commonly referred to as bore in British English) of a firearm is a unit of measurement used to express the inner diameter (bore diameter) and other necessary parameter to define in general a smoothbore barrel (in difference of caliber what define a barrel with rifling and there cartridge).

d n = 2 3 4 π 1   l b / n 0.4097   l b / i n 3 3 {\displaystyle d_{n}=2{\sqrt[{3}]{{\frac {3}{4\pi }}{\frac {1\mathrm {~lb} /n}{0.4097\mathrm {~lb/in^{3}} }}}}}

In 1869, Jules Suriray received a patent for a radial ball bearing to be fitted into metal bicycles. The success of the improved design led to the creation of several new types of metal ball bearings, all with different designs that were specially created for a particular machine.

Gauge is determined from the weight of a solid sphere of lead that will fit the bore of the firearm and is expressed as the multiplicative inverse of the sphere's weight as a fraction of a pound, e.g., a one-twelfth pound lead ball fits a 12-gauge bore. Therefore with a 12-gauge, it would take 12 balls of lead of the same size as the 12 gauge shotgun's inner bore diameter to weigh 1 pound (454 grams).[1] The term is related to the measurement of cannons, which were also measured by the weight of their iron round shot; an eight-pounder would fire an 8 lb (3.6 kg) ball. Therefore, a 12 gauge is larger than a 16 gauge.

Shotguns and shells exceeding 10 gauge, such as the 8 gauge, 6 gauge, 4 gauge, and 2 gauge are historically important in the United Kingdom and elsewhere in mainland Europe. Today, they are rarely manufactured. These shells are usually black powder paper or brass cartridges, as opposed to modern smokeless powder plastic or wax cartridges.

What is Boresize in pipe

Note: Use of this table for estimating bullet masses for historical large-bore rifles is limited, as this table assumes the use of round ball, rather than conical bullets; for example, a typical 4-bore rifle from circa 1880 used a 2,000-grain (4.57 oz; 129.60 g) bullet, or sometimes slightly heavier, rather than using a 4-ounce (110 g) round lead ball. (Round balls lose velocity faster than conical bullets and have much steeper ballistic trajectories beyond about 75 yards or 69 metres) In contrast, a 4-bore express rifle often used a 1,500-grain (3.43 oz; 97.20 g) bullet wrapped in paper to keep lead buildup to a minimum in the barrel. In either case, assuming a 4-ounce (110 g) mass for a 4-bore rifle bullet from this table would be inaccurate, although indicative.

Bearingboresize chart

With the rise of improved metal forming processes at the start of the industrial age, it was determined that bearings made of steel were far better at their job than wooden or bronze bearings. Philip Vaughan received a patent for a ball bearing in 1794, and his design became the basic blueprint for the creation of the modern ball bearing. A dramatic reduction in friction led to far more efficient machines, which was responsible for machines being manufactured in far greater numbers, leading to the creation of factories.

Also seen in limited numbers are smoothbore firearms in calibers smaller than .360 such as .22 Long Rifle (UK No. 1 bore) and 9mm Flobert rimfire (UK No. 3 bore), designed for short-range pest control and garden guns. The No. 2 bore (7 mm) has long been obsolete. All three of these rimfires are available in shot and BB-cap.[7][8]

Since shotguns were not originally intended to fire solid projectiles, but rather a compressible mass of shot, the actual diameter of the bore can vary. The fact that most shotgun bores are not cylindrical also causes deviations from the ideal bore diameter.

The 10 gauge narrowly escaped obsolescence when steel and other nontoxic shot became required for waterfowl hunting, since the larger shell could hold the much larger sizes of low-density steel shot needed to reach the ranges necessary for waterfowl hunting. The move to steel shot reduced the use of 16 and 20 gauges for waterfowl hunting, and the shorter, 2+3⁄4-inch (70 mm), 12-gauge shells as well. However, the 3+1⁄2-inch (89 mm) 12-gauge shell, with its higher SAAMI pressure rating of 14,000 psi (97 MPa) compared to standard 2+3⁄4-inch (70 mm) and 3-inch (76 mm) 12-gauge shells with their lower pressure rating of 11,500 psi (79 MPa), began to approach the performance of the 3+1⁄2-inch (89 mm) 10-gauge shells with a pressure rating of 11,000 psi (76 MPa).[9] Newer nontoxic shots, such as bismuth or tungsten-nickel-iron alloys, and even tungsten-polymer blends, regain much or all of the performance loss, but are much more expensive than steel or lead shot.[10] However, laboratory research indicates that tungsten alloys can actually be quite toxic internally.[11]

Bearings were also put to use in smaller devices such as watches, where sapphire bearings allowed for more precise timekeeping. Water mills also made use of increasingly sophisticated bearings to make the process of drawing water less difficult.

The evidence of such a mechanism is evident through cave drawings, and at a later time, through Egyptian pyramid drawings, which show wooden rollers being used to move heavy stones during construction. Various liquids were also used to provide lubrication to the bearings and make their motion smoother. Different materials were experimented upon to create better bearings, from bronze to zinc, although they were found to be inadequate in providing support to the heavy-duty automated machinery that was to come later.

Metallurgical processes improved as humanity's understanding of chemistry increased, leading to harder, more wear-resistant materials. Improved lubricants made it possible for bearings to operate at higher speeds and temperatures. New and improved bearings are today put to use in a variety of machines, big and small, from dental drills to the Mars Rover spaceship.