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62-413: The camera bodies are complex; for example, the first model includes nearly 1100 parts, with seven principal alloy pressure castings and additional stamped cover plates to complete the structure. However, it is rugged and roller bearings are used in the aperture mechanism. Inevitably it requires a specialist for its repair; 43 parts have to be dismantled to remove the top plate for internal access. There

124-467: A tire flattens where it contacts the road. The race also yields slightly where each ball presses against it. Thus, the contact between ball and race is of finite size and has finite pressure. The deformed ball and race do not roll entirely smoothly because different parts of the ball are moving at different speeds as it rolls. Thus, there are opposing forces and sliding motions at each ball/race contact. Overall, these cause bearing drag. Roller bearings are

186-462: A ball bearing or a spherical roller bearing. As in all radial bearings, the outer load is continuously re-distributed among the rollers. Often fewer than half of the total number of rollers carry a significant portion of the load. The animation on the right shows how a static radial load is supported by the bearing rollers as the inner ring rotates. Spherical roller bearings have an outer race with an internal spherical shape. The rollers are thicker in

248-470: A bearing assembly are also affected by the speed of operation: rolling-element bearings may spin over 100,000 rpm, and the principal load in such a bearing may be momentum rather than the applied load. Smaller rolling elements are lighter and thus have less momentum, but smaller elements also bend more sharply where they contact the race, causing them to fail more rapidly from fatigue. Maximum rolling-element bearing speeds are often specified in 'nD m ', which

310-488: A cage, which is then placed between the two flat surfaces; a common example is drawer-support hardware. Roller-element bearing for a shaft use bearing balls in a groove designed to recirculate them from one end to the other as the bearing moves; as such, they are called linear ball bearings or recirculating bearings . Rolling-element bearings often work well in non-ideal conditions, but sometimes minor problems cause bearings to fail quickly and mysteriously. For example, with

372-500: A longer lifetime for a correctly-used bearing below its design load, or also as the increased rate by which lifetime is shortened when overloaded. This model was recognised to have become inaccurate for modern bearings. Particularly owing to improvements in the quality of bearing steels, the mechanisms for how failures develop in the 1924 model are no longer as significant. By the 1990s, real bearings were found to give service lives up to 14 times longer than those predicted. An explanation

434-457: A matching viewfinder. The viewfinder had seven elements, more than the lens itself. The field of view was so wide the camera was bundled with an accessory pistol grip that screws into the tripod socket to prevent inadvertent inclusion of the photographer's hands in the image. To compensate for vignetting, a radially-graduated neutral density filter was included. The Hologon was built from 1969 to 1972, when Zeiss Ikon ceased camera production. Like

496-577: A number of smaller 'satellite' gears which revolve around the center of the bearing along a track on the outsides of the internal and satellite gears, and on the inside of the external gear. The downside to this bearing is manufacturing complexity. Tapered roller bearings use conical rollers that run on conical races. Most roller bearings only take radial or axial loads, but tapered roller bearings support both radial and axial loads, and generally can carry higher loads than ball bearings due to greater contact area. Tapered roller bearings are used, for example, as

558-971: A shaft in a much larger hole, and spheres or cylinders called "rollers" tightly fill the space between the shaft and hole. As the shaft turns, each roller acts as the logs in the above example. However, since the bearing is round, the rollers never fall out from under the load. Rolling-element bearings have the advantage of a good trade-off between cost, size, weight, carrying capacity, durability, accuracy, friction, and so on. Other bearing designs are often better on one specific attribute, but worse in most other attributes, although fluid bearings can sometimes simultaneously outperform on carrying capacity, durability, accuracy, friction, rotation rate and sometimes cost. Only plain bearings are used as widely as rolling-element bearings. Common mechanical components where they are widely used are – automotive, industrial, marine, and aerospace applications. They are products of great necessity for modern technology. The rolling element bearing

620-457: A split image inside of a micro-prism. A thumb-wheel on the camera controls the lens aperture, and the value is shown in a window on top of the centrally located meter cell (the Cyclops window ). The shutter speed dial is lifted and rotated to set the film speed. The aperture in the interchangeable automatic lens closes when the shutter release is depressed and reopens when the camera is wound on for

682-444: A stationary (non-rotating) load, small vibrations can gradually press out the lubricant between the races and rollers or balls ( false brinelling ). Without lubricant the bearing fails, even though it is not rotating and thus is apparently not being used. For these sorts of reasons, much of bearing design is about failure analysis. Vibration based analysis can be used for fault identification of bearings. There are three usual limits to

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744-530: A waist-level finder. The Contarex Professional or P (catalog 10.2700) replaced the Special with updated cosmetics, and like the Special , also deleted the internal light meter. It was built from 1966 to 1967. Unlike the Special , the Professional was equipped with a fixed eye-level pentaprism viewfinder. The Professional was the first model released in the second generation of Contarex SLR cameras (spanning

806-416: Is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, grooved rings called races . The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding . One of the earliest and best-known rolling-element bearings are sets of logs laid on the ground with a large stone block on top. As

868-474: Is a prominent wheel for the photographer's right index finger, on the top corner of the lens mount escutcheon, which controls aperture. This detail was reminiscent of the focusing wheel on pre-war Contax rangefinder cameras, and was carried throughout the Contarex SLR line. Shutter speeds are controlled by a dial coaxial with and at the base of the film winding lever / exposure counter / shutter release button at

930-418: Is a special type of roller bearing which uses long, thin cylindrical rollers resembling needles. Often the ends of the rollers taper to points, and these are used to keep the rollers captive, or they may be hemispherical and not captive but held by the shaft itself or a similar arrangement. Since the rollers are thin, the outside diameter of the bearing is only slightly larger than the hole in the middle. However,

992-545: Is based on it. The concept of fatigue limit, and thus ISO 281:2007, remains controversial, at least in the US. In 2015, the SKF Generalized Bearing Life Model (GBLM) was introduced. In contrast to previous life models, GBLM explicitly separates surface and subsurface failure modes – making the model flexible to accommodate several different failure modes. Modern bearings and applications show fewer failures, but

1054-419: Is instead related to in statistical terms, referring to populations of bearings. All information with regard to load ratings is then based on the life that 90% of a sufficiently large group of apparently identical bearings can be expected to attain or exceed. This gives a clearer definition of the concept of bearing life, which is essential to calculate the correct bearing size. Life models can thus help to predict

1116-460: Is needed. Rolling-element bearings are often used for axles due to their low rolling friction. For light loads, such as bicycles, ball bearings are often used. For heavy loads and where the loads can greatly change during cornering, such as cars and trucks, tapered rolling bearings are used. Linear motion roller-element bearings are typically designed for either shafts or flat surfaces. Flat surface bearings often consist of rollers and are mounted in

1178-528: Is set on the camera aperture wheel. The Contarex lens mount takes only Contarex lenses and accessories. The lenses Zeiss designed and manufactured for the Contarex cameras have been called "the best 35 mm lenses that have ever been made". According to noted Leica historian and reviewer Erwin Puts, "Zeiss designers gave the most attention to flatness of field and the reduction of astigmatism. [...] The characteristics of

1240-465: Is that bearing life is finite, and reduces by a cube power of the ratio between design load and applied load. This model was developed in 1924, 1947 and 1952 work by Arvid Palmgren and Gustaf Lundberg in their paper Dynamic Capacity of Rolling Bearings . The model dates from 1924, the values of the constant p {\displaystyle p} from the post-war works. Higher p {\displaystyle p} values may be seen as both

1302-410: Is that, like a cylindrical roller, they do not locate axially. CARB bearings are typically used in pairs with a locating bearing, such as a spherical roller bearing . This non-locating bearing can be an advantage, as it can be used to allow a shaft and a housing to undergo thermal expansion independently. Toroidal roller bearings were introduced in 1995 by SKF as "CARB bearings". The inventor behind

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1364-420: Is the ball bearing . The bearing has inner and outer races between which balls roll. Each race features a groove usually shaped so the ball fits slightly loose. Thus, in principle, the ball contacts each race across a very narrow area. However, a load on an infinitely small point would cause infinitely high contact pressure. In practice, the ball deforms (flattens) slightly where it contacts each race much as

1426-465: Is the Carl Zeiss Planar 1:2 f=50mm in bright aluminium finish with a chrome 49 mm thread filter ring and an outer bayonet for Zeiss-Ikon filters. The lens focuses to 0.3 m (1 ft 0 in), which is closer than the usual 0.5 m (1 ft 8 in) for a normal lens. The focusing helical is remarkably smooth and precise. There is no aperture ring on the Contarex lens itself. It

1488-470: Is the life that 90% of bearings can be expected to reach or exceed. The median or average life, sometimes called Mean Time Between Failure (MTBF), is about five times the calculated basic rating life. Several factors, the ' ASME five factor model', can be used to further adjust the L 10 {\displaystyle L_{10}} life depending upon the desired reliability, lubrication, contamination, etc. The major implication of this model

1550-479: Is the presence of water in the lubrication oil. Online water-in-oil monitors have been introduced in recent years to monitor the effects of both particles and the presence of water in oil and their combined effect. Metric rolling-element bearings have alphanumerical designations, defined by ISO 15 , to define all of the physical parameters. The main designation is a seven digit number with optional alphanumeric digits before or after to define additional parameters. Here

1612-524: Is the product of the mean diameter (in mm) and the maximum RPM. For angular contact bearings nD m s over 2.1 million have been found to be reliable in high performance rocketry applications. There are also many material issues: a harder material may be more durable against abrasion but more likely to suffer fatigue fracture, so the material varies with the application, and while steel is most common for rolling-element bearings, plastics, glass, and ceramics are all in common use. A small defect (irregularity) in

1674-451: The Bullseye with the same updated cosmetics of the Professional . It was built from 1967 to 1972, when Zeiss Ikon ceased camera production. The internal meter for second-generation Contarex models so equipped ( Super and Super Electronic ) used a CdS through-the-lens photoresistor , rather than the external selenium meter of the first-generation Bullseye . The meter power switch is on

1736-421: The Professional , Super , and Electronic ); the updated appearance included replacing the script "Contarex" logo of the first generation ( Bullseye and Special ) with a blocky typeface set on a black background on the front of the pentaprism viewfinder housing. In addition, the film speed setting/reminder dial was moved to be coaxial with the rewind knob. The Contarex Super or S (catalog 10.2600) succeeded

1798-409: The earliest known type of rolling-element-bearing, dating back to at least 40 BC. Common roller bearings use cylinders of slightly greater length than diameter. Roller bearings typically have a higher radial load capacity than ball bearings, but a lower capacity and higher friction under axial loads. If the inner and outer races are misaligned, the bearing capacity often drops quickly compared to either

1860-460: The Contarex lenses are reminiscent of the Hasselblad lenses. Stopped down a bit they exhibit a remarkable finesse of gradation and depth. They may not be the sharpest lenses ever, but the rendition of shape outlines and surface details is most pleasing and subtle like a poem." Rolling-element bearing In mechanical engineering , a rolling-element bearing , also known as a rolling bearing ,

1922-539: The SE was capable of aperture-priority autoexposure . The Contarex Hologon was a fixed-lens camera that used the same stripped-down second-generation chassis as the microscope camera, which removed the reflex mirror and viewfinder mechanisms, featuring mechanically-controlled shutter speeds ranging from 1– 1 ⁄ 500 s plus "B"ulb and "T"imer. It was purpose-built to carry the fixed-focus, fixed-aperture, three-element Hologon 15 mm f /8 ultra wide angle lens and

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1984-503: The Super and Electronic, a few cameras were assembled later. Some Hologon cameras have been disassembled for their lenses, which were fitted with Leica M bayonet mounts. The Contarex Microscope used the chassis of the Super , stripped of its viewfinder and mirror assembly. Shutter speeds for the focal plane shutter range from 1– 1 ⁄ 500  sec with B and T settings. The standard lens

2046-580: The U.S. Space Shuttle which could not be adequately isolated from the liquid oxygen being pumped. All lubricants reacted with the oxygen, leading to fires and other failures. The solution was to lubricate the bearing with the oxygen. Although liquid oxygen is a poor lubricant, it was adequate, since the service life of the pump was just a few hours. The operating environment and service needs are also important design considerations. Some bearing assemblies require routine addition of lubricants, while others are factory sealed , requiring no further maintenance for

2108-592: The ability to take on axial loading and radial loading and how it does this is by using a conical structure enabling the elements to roll diagonally. Barrel -  Provides assistance to high radial socks loads that cause misalignment and uses its shape and size for compensation. Needle - Varying in size, diameters, and materials these types of bearings are best suited for helping reduce weight as well as smaller cross sections application, typically higher load capacity than ball bearings and rigid shaft applications. A particularly common kind of rolling-element bearing

2170-590: The bearing was the engineer Magnus Kellström. The configuration of the races determine the types of motions and loads that a bearing can best support. A given configuration can serve multiple of the following types of loading. Thrust bearings are used to support axial loads, such as vertical shafts. Common designs are Thrust ball bearings , spherical roller thrust bearings , tapered roller thrust bearings or cylindrical roller thrust bearings. Also non-rolling-element bearings such as hydrostatic or magnetic bearings see some use where particularly heavy loads or low friction

2232-403: The bearing. For example, on radial thrust bearings the digits define the contact angle, or the presence of seals on any bearing type. The seventh digit defines the "width series", or thickness, of the bearing. The width series, defined from lightest to heaviest, is: 7, 8, 9, 0, 1 (extra light series), 2 (light series), 3 (medium series), 4 (heavy series). The third digit and the seventh digit define

2294-430: The board consisting of the outer and inner track, a central bore, a retainer to keep the rolling elements from clashing into one another or seizing the bearing movement, and the rolling elements themselves. The internal rolling  components may differ in design due to their intended purpose of application of the bearing.  The main five types of bearings are Ball, Cylindrical, Tapered, Barrel, and Needle. Ball -

2356-485: The digits will be defined as: 7654321. Any zeros to the left of the last defined digit are not printed; e.g. a designation of 0007208 is printed 7208. Digits one and two together are used to define the inner diameter (ID), or bore diameter, of the bearing. For diameters between 20 and 495 mm, inclusive, the designation is multiplied by five to give the ID; e.g. designation 08 is a 40 mm ID. For inner diameters less than 20

2418-510: The effects of lubrication, contamination, and race surface properties, which together influence the stress distribution in the rolling contact. In 2019, the Generalized Bearing Life Model was relaunched. The updated model offers life calculations also for hybrid bearings, i.e. bearings with steel rings and ceramic (silicon nitride) rolling elements. Even if the 2019 GBLM release was primarily developed to realistically determine

2480-421: The failures that do occur are more linked to surface stresses. By separating surface from the subsurface, mitigating mechanisms can more easily be identified. GBLM makes use of advanced tribology models to introduce a surface distress failure mode function, obtained from the evaluation of surface fatigue. For the subsurface fatigue, GBLM uses the classical Hertzian rolling contact model. With all this, GBLM includes

2542-547: The first NASA extra vehicular activity ( EVA ) on June 3, 1965, during the flight of Gemini 4 . Geoffrey Crawley published an extensive review of the Contarex Super and lens system in 1970 for the British Journal of Photography . The Contarex I , aka Bullseye (catalog 10.2401), was built between 1959 and 1966. It was the first 35mm SLR camera with a focal plane shutter that provides direct light meter coupling to

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2604-399: The following designations are used: 00 = 10 mm ID, 01 = 12 mm ID, 02 = 15 mm ID, and 03 = 17 mm ID. The third digit defines the "diameter series", which defines the outer diameter (OD). The diameter series, defined in ascending order, is: 0, 8, 9, 1, 7, 2, 3, 4, 5, 6. The fourth digit defines the type of bearing: The fifth and sixth digit define structural modifications to

2666-466: The idea of a 'fatigue limit' entered bearing lifetime calculations. If the bearing was not loaded beyond this limit, its theoretical lifetime would be limited only by external factors, such as contamination or a failure of lubrication. A new model of bearing life was put forward by FAG and developed by SKF as the Ioannides-Harris model. ISO 281:2000 first incorporated this model and ISO 281:2007

2728-416: The life of the mechanical assembly. Although seals are appealing, they increase friction, and in a permanently sealed bearing the lubricant may become contaminated by hard particles, such as steel chips from the race or bearing, sand, or grit that gets past the seal. Contamination in the lubricant is abrasive and greatly reduces the operating life of the bearing assembly. Another major cause of bearing failure

2790-483: The lifetime or load capacity of a bearing: abrasion, fatigue and pressure-induced welding. Although there are many other apparent causes of bearing failure, most can be reduced to these three. For example, a bearing which is run dry of lubricant fails not because it is "without lubricant", but because lack of lubrication leads to fatigue and welding, and the resulting wear debris can cause abrasion. Similar events occur in false brinelling damage. In high speed applications,

2852-545: The material is often responsible for bearing failure; one of the biggest improvements in the life of common bearings during the second half of the 20th century was the use of more homogeneous materials, rather than better materials or lubricants (though both were also significant). Lubricant properties vary with temperature and load, so the best lubricant varies with application. Although bearings tend to wear out with use, designers can make tradeoffs of bearing size and cost versus lifetime. A bearing can last indefinitely—longer than

2914-434: The middle and thinner at the ends. Spherical roller bearings can thus accommodate both static and dynamic misalignment. However, spherical rollers are difficult to produce and thus expensive, and the bearings have higher friction than an ideal cylindrical or tapered roller bearing since there will be a certain amount of sliding between rolling elements and races. Gear bearings are similar to epicyclic gearing . They consist of

2976-472: The next exposure. Due to the limited meter range, not every camera setting combination is possible to accommodate on the Contarex I exposure meter. The Contarex Special (catalog 10.2500) was equivalent to the Bullseye , but the Special omitted the selenium cell meter. It was built from 1960 to 1966. The viewfinder of the Special is removable and two styles were available: a pentaprism, for eye-level use, or

3038-465: The oil flow also reduces the bearing metal temperature by convection. The oil becomes the heat sink for the friction losses generated by the bearing. ISO has categorised bearing failures into a document Numbered ISO 15243. The life of a rolling bearing is expressed as the number of revolutions or the number of operating hours at a given speed that the bearing is capable of enduring before the first sign of metal fatigue (also known as spalling ) occurs on

3100-475: The opposite side of the lens mount escutcheon from the aperture setting wheel. The Contarex Super Electronic or SE (catalog 10.2800) used the chassis of the Super , fitted with an electronically-controlled shutter. It was built from 1968 to 1972, when Zeiss Ikon ceased camera production. A few cameras were assembled later, with the Carl Zeiss brand instead of Zeiss Ikon. With a "photoelectric timer" attachment,

3162-583: The performance of a bearing more realistically. The prediction of bearing life is described in ISO 281 and the ANSI /American Bearing Manufacturers Association Standards 9 and 11. The traditional life prediction model for rolling-element bearings uses the basic life equation: L 10 = ( C / P ) p {\displaystyle L_{10}=(C/P)^{p}} Where: Basic life or L 10 {\displaystyle L_{10}}

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3224-471: The photographer's right hand. Contarex SLRs featured a slip-off back, which could be removed and replaced by an interchangeable magazine back (catalog 20.0304). This magazine back concept was shared with the Contaflex SLR , although Contarex magazine backs are wider and physically incompatible with Contaflex cameras and vice versa. A custom modified Contarex Special was used by astronaut Ed White during

3286-611: The race of the inner or outer ring, or on a rolling element. Calculating the endurance life of bearings is possible with the help of so-called life models. More specifically, life models are used to determine the bearing size – since this must be sufficient to ensure that the bearing is strong enough to deliver the required life under certain defined operating conditions. Under controlled laboratory conditions, however, seemingly identical bearings operating under identical conditions can have different individual endurance lives. Thus, bearing life cannot be calculated based on specific bearings, but

3348-415: The rest of the machine—if it is kept cool, clean, lubricated, is run within the rated load, and if the bearing materials are sufficiently free of microscopic defects. Cooling, lubrication, and sealing are thus important parts of the bearing design. The needed bearing lifetime also varies with the application. For example, Tedric A. Harris reports in his Rolling Bearing Analysis on an oxygen pump bearing in

3410-448: The shutter-, aperture-, and film speed -settings; they are interconnected by cords. An aperture simulator for the exposure meter in the Cyclops window uses an iris in front of the selenium meter cell. To set the proper exposure, the meter needle is aligned with an index triangle, which is visible both in a top plate window and to the right side of the viewfinder. The camera also has an interchangeable focusing screen which is, by default,

3472-418: The simplest following the basic principles with minimal design intention. Important to note the ability for more seizures is likely due to the freedom of the track design.   Cylindrical - For single axis movement for straight directional movement. The shape allows for more surface area to be in contact adding in moving more weight with less force at a greater distance. Tapered -  Primarily focused on

3534-494: The small-diameter rollers must bend sharply where they contact the races, and thus the bearing fatigues relatively quickly. CARB bearings are toroidal roller bearings and similar to spherical roller bearings , but can accommodate both angular misalignment and also axial displacement. Compared to a spherical roller bearing, their radius of curvature is longer than a spherical radius would be, making them an intermediate form between spherical and cylindrical rollers. Their limitation

3596-409: The stone is pulled, the logs roll along the ground with little sliding friction . As each log comes out the back, it is moved to the front where the block then rolls on to it. It is possible to imitate such a bearing by placing several pens or pencils on a table and placing an item on top of them. See " bearings " for more on the historical development of bearings. A rolling element rotary bearing uses

3658-458: The wheel bearings of most wheeled land vehicles. The downsides to this bearing is that due to manufacturing complexities, tapered roller bearings are usually more expensive than ball bearings; and additionally under heavy loads the tapered roller is like a wedge and bearing loads tend to try to eject the roller; the force from the collar which keeps the roller in the bearing adds to bearing friction compared to ball bearings. The needle roller bearing

3720-431: The working life of hybrid bearings, the concept can also be used for other products and failure modes. All parts of a bearing are subject to many design constraints. For example, the inner and outer races are often complex shapes, making them difficult to manufacture. Balls and rollers, though simpler in shape, are small; since they bend sharply where they run on the races, the bearings are prone to fatigue. The loads within

3782-582: Was developed from a firm foundation that was built over thousands of years. The concept emerged in its primitive form in Roman times . After a long inactive period in the Middle Ages, it was revived during the Renaissance by Leonardo da Vinci , and developed steadily in the seventeenth and eighteenth centuries. Design description Bearings, especially rolling element bearings are designed in similar fashion across

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3844-667: Was put forward based on fatigue life ; if the bearing was loaded to never exceed the fatigue strength , then the Lundberg-Palmgren mechanism for failure by fatigue would simply never occur. This relied on homogeneous vacuum-melted steels , such as AISI 52100 , that avoided the internal inclusions that had previously acted as stress risers within the rolling elements, and also on smoother finishes to bearing tracks that avoided impact loads. The p {\displaystyle p} constant now had values of 4 for ball and 5 for roller bearings. Provided that load limits were observed,

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