- DZIAŁ:
- Home page /
- History of bearings
History of bearings
HISTORY OF BEARINGS
1. From ancient times up to the XX century.
Bearings, so widely used in the present day, have already been used by people more than a thousand years back. The rolling bearing is one such example of the original discovery. The evolution of the first ever bearing in to its present form, has led to the development of many transitional forms.
Before we begin discussing, step by step, the history behind bearings, it would be good to take a brief look at Tribology - the science of friction and accompanying processes. Tribology dates back to primitive man, striking stone against stone, unconsciously taking advantage of friction to create energy. Before the discovery of the wheel, material was transported on sleds pulled by people and animals which meant the need to overcome sliding friction (drawing no.1).
Rys. 1.
Before having evolved in to a form closely resembling that of the present day, the development of the bearing underwent many phases of development. Almost as far back as the II century b.c., this discovery was exploited in the transportation of heavy objects such as rock blocks used for building or war machines which were pushed on wooden rollers. Such methods have widely been used in Egypt and Assyria in order to minimize friction resistance (drawing no.2).
Rys. 2
A similar technique used to change sliding resistance in to rolling resistance has been used in the ancient city of Behen in Nubia during the construction of an Egyptian fortress, whose drawbridge was moved by pushing it over wooden rollers. In the VI century b.c., this subject had been discussed by Aristotle in a disquisition which discussed the theory of rolling resistance.
A breakthrough in the age old struggle to lessen the resistance associated with movement came in the form of the wheel which was discovered approximately 3000 years b.c. and took sliding movement to rolling movement. The oldest found slide bearings date back to the Neolithic era which saw the mastering of drilling holes in stone. These stone bearings were used in the first drilling machines as well as spinning spindles. Later, they were used in all sorts of simple equipment like chariots, arbalests, wheelbarrows, turntables and stone grinding wheels (drawing no.3).
Rys. 3.
In order to reduce friction which wasted huge amounts of energy, the bearings were lubricated. At first, this was achieved through the use of vegetable oils. These in turn had low viscosity, low flow resistance and were prone to drying. A far better option constituted animal fat which was later to be enriched with mineral thickening agents. Cart axles were lubricated by way of all sorts of wood tar derived greases. In areas where crude oil could be found seeping through the grounds surface, grease was obtained by heating oil for extended periods of time.
Archaeological research has shown that chariots of ancient rulers found in their tombs had grease residues of the axles. The resulting analyses have shown a presence of animal fats mixed with mineral thickeners (and a melting point of 50° C). Plinius of Rome (23 - 73 a.d.) drew up a list of various vegetable oils and animal fats used as lubricating agents. These lubricating agents have dominated the scene up to the discovery of the steam engine. Relatively widespread use of mineral oils appeared in the beginning of the 20th century.
The first mechanism which could be looked upon as a prototype of the rolling bearing mechanism was designed by a Greek engineer by the name of Diades at around 330 b.c. This design constituted the head of a tower used to crumble city walls (drawing no.4).
Rys.4
This construction featured a ram which rested on rollers that moved along running tracks gouged out at its base. The rollers were held by a common bearing cage, powered by ropes tied to its ends which continued over fixed type rollers. The interesting thing about this type of construction is that not only has the way in which modern type bearings work been applied for the first time, it also boasted transfer of movement by way of rolling contact, which is used widely in modern frictional variable-speed transmissions.
The first axial bearing dates back to the late Kaliguli era. Archaeologists have discovered a turntable on a ship dating back to that time (1 a.d.). One of the turntables discovered had turning capability thanks to a set of wheels that it rested on, which were fixed around the circumference of the wheel.
A second turntable featured balls instead of wheels, each one of which was linked to the turntable by means of a king-pin. The third one featured eight wooden truncated cone shaped rollers which were all pivoted. The turntable mechanism consisted of two wooden boards, of which the lower featured a pivot that kept both boards axially aligned. The top board featured eight depressions with round roller elements inside. These elements were held by pivots loosely attached to the top board, limiting their movement to a single axis. Despite the fact that the pivots themselves carried the weight and made true rolling impossible, this is the first noted instance of using ball shaped rolling elements for the purpose of transferring weight. (drawing no.5)
Rys. 5
The turntable mechanisms discovered are early examples of modern ball roller and cone bearings. Even in those early times, it had been noted that it was better to use ball shaped elements instead of roller shaped elements in thrust bearing designs.
From As of the beginning of our era up to the beginning of the Renaissance, No information can be found on the development of rolling bearings. Leonardo da Vinci made use of roller supports in many of his design projects but these were hardly ever put in to practice up until the beginning of the XVIII century (drawing no. 6). He can thus be considered the inventor of the rolling bearing. Leonardo da Vinci has made a drawing of a revolutionary pivot bearing whose originality is exemplified by the changing of sliding resistance into greatly reduced rolling resistance. This idea was to be exploited up to the end of the XIX century in the form of a ball bearing consisting of an external and internal ring with moving balls in between.
Rys. 6.
The oldest example of a rolling bearing comes from the support of a windmill (drawing no.7) which was built in 1780 in Sprowston, England. It consisted of two separate cast iron ball races holding forty iron balls. It is worth noting that the ratio of the ball race furrow and balls was 1,22 and was a bit bigger that that of modern designs, which made it clear that there was an awareness of the need to reduce movement resistance caused by slippage at the point of contact.
Rys. 7
The XIX century saw further improvements in the design of rolling bearings and their increased use in machinery and equipment. But it was the introduction of abrasive machining toward the end of the last century that facilitated the attaining of sufficient hardness and precision of bearing elements. In the beginning, metal balls were produced from steel rods, which were produced manually. This lack of precision led to an uneven spread of weight which resulted in bearing deformation. The turning point in ball machining was the work of a technician and inventor by the name of Friedrich Fischer, the son of Plilippe Moritz Fischer. Friedrich constructed a steel ball machining device, the first bearing bicycle (1853), invented the first fully automated milling machine which used a similar operating method to that of a grinding stone. Fischer's discovery made it possible to machine hardened steel balls � a grinding process that gave them an even shape. Thanks to this innovation Fischer's steel balls triumphantly entered world markets.
2. The present day
Ball bearings could not be applied in all areas. Further research has thus led to the development of cone, rolling and needle bearings.
In 1907, a young Swedish engineer by the name of Sven Wingquist made a sketch in his diary of the first self-aligning bearing. The post World War I period saw the replacement of the slide bearing by anti-friction bearings. This process was further augmented by the appearance of the rolling bearing � at around 1920 - capable of handling huge loads. Soon thereafter, appeared many derivatives like needle bearings, followed by cone bearings. The significant improvement of slide bearings can be assigned to O. Reynolds and N.P. Pietrow, who independently studied the effects of hydrodynamics. The idea behind this is that with the right amount of shaft revolutions, the layer of oil develops antogeneous pressure which lifts the shaft, thus keeping it from coming into contact with the bearing itself. The testing of this effect led to the construction of hydrostatic slide bearings used in low friction characteristics. Further development saw the introduction of hydrostatic slide bearings used in low revolution machines and those equipped with heavy rotors with pressurised oil fed from the outside. This type of technology is usually found in large steam turbines with horizontal axles, water turbines with vertical axles and large industrial centrifuges.
At around 1945, the development of powder metallurgy has led to the development of oilless slide bearings made of porous materials saturated with grease of from ceramet type agglomerates (bronze/graphite) which lasted long when used in small machinery. In high revolution centrifuges as well as gyroscopes, air serves as lubricant (air bearing).
Another widely used innovation is that of hybrid bearings. The traditional way of increasing bearing resistance is achieved through the use of balls that are hollow or low in weight. An alternative to this solution is the coupling of a ball bearing with a hydrostatic bearing. The workload between the two bearings is divided 50:50, resulting in a ten fold increase in the durability of the ball bearing in relation to an unassisted ball bearing working under the same conditions. IN this design, the outer bearing race of the ball bearing is encased in a stationary enclosure. The inner bearing race is mounted to a bearing sleeve which can rotate independently of the shaft.
The bearing production process sees the implementation of many innovations which facilitate production of more precise, faster and cheaper solutions. One such innovation is torque reduction technology, an example of which is the torque bearing, developed for use iln trains. This technology has led to considerable decreases in fuel consumption.
Yet the greatest breakthrough in bearing design occurred with the introduction of computer technology. Computers enable the analysis of all possible aspects of a set of bearings. Virtual bearings created by means of computer aided design can undergo extensive testing without the need to start technological processes. Advanced computer programmes enable quick assignment of virtually any external or internal parameters. This technology was used in the creation of micro bearings used in microelectronics, e.g. hard disks.
Almost up to the end of the XX century, the traditional material from which bearings were manufactured was steel which was modified in order to meet various needs. But the physical characteristics of steel imposed upon the design engineers a specific framework of applications. Key characteristics of steel include heat expansion, high density, corrosion susceptibility, electric and magnetic conductivity and a high friction ratio, even after precise finishing. The material that opened the door to new possibilities, unattainable for bearings turned out to be silicon nitride - a ceramic composite. This material was initially used solely for the creation of rolling elements. Excellent examples are hybrid, high revolution angular ball bearings. Only a couple of years later, design engineers have started designing bearings whose working parts are also made from ceramic materials (ceramic bearings), i.e. high revolution roll-neck bearings. To compare, the ceramic bearing is capable of working at twice the revolution speed of its steel counterpart.
1. From ancient times up to the XX century.
Bearings, so widely used in the present day, have already been used by people more than a thousand years back. The rolling bearing is one such example of the original discovery. The evolution of the first ever bearing in to its present form, has led to the development of many transitional forms.
Before we begin discussing, step by step, the history behind bearings, it would be good to take a brief look at Tribology - the science of friction and accompanying processes. Tribology dates back to primitive man, striking stone against stone, unconsciously taking advantage of friction to create energy. Before the discovery of the wheel, material was transported on sleds pulled by people and animals which meant the need to overcome sliding friction (drawing no.1).
Rys. 1.
Before having evolved in to a form closely resembling that of the present day, the development of the bearing underwent many phases of development. Almost as far back as the II century b.c., this discovery was exploited in the transportation of heavy objects such as rock blocks used for building or war machines which were pushed on wooden rollers. Such methods have widely been used in Egypt and Assyria in order to minimize friction resistance (drawing no.2).
Rys. 2
A similar technique used to change sliding resistance in to rolling resistance has been used in the ancient city of Behen in Nubia during the construction of an Egyptian fortress, whose drawbridge was moved by pushing it over wooden rollers. In the VI century b.c., this subject had been discussed by Aristotle in a disquisition which discussed the theory of rolling resistance.
A breakthrough in the age old struggle to lessen the resistance associated with movement came in the form of the wheel which was discovered approximately 3000 years b.c. and took sliding movement to rolling movement. The oldest found slide bearings date back to the Neolithic era which saw the mastering of drilling holes in stone. These stone bearings were used in the first drilling machines as well as spinning spindles. Later, they were used in all sorts of simple equipment like chariots, arbalests, wheelbarrows, turntables and stone grinding wheels (drawing no.3).
Rys. 3.
In order to reduce friction which wasted huge amounts of energy, the bearings were lubricated. At first, this was achieved through the use of vegetable oils. These in turn had low viscosity, low flow resistance and were prone to drying. A far better option constituted animal fat which was later to be enriched with mineral thickening agents. Cart axles were lubricated by way of all sorts of wood tar derived greases. In areas where crude oil could be found seeping through the grounds surface, grease was obtained by heating oil for extended periods of time.
Archaeological research has shown that chariots of ancient rulers found in their tombs had grease residues of the axles. The resulting analyses have shown a presence of animal fats mixed with mineral thickeners (and a melting point of 50° C). Plinius of Rome (23 - 73 a.d.) drew up a list of various vegetable oils and animal fats used as lubricating agents. These lubricating agents have dominated the scene up to the discovery of the steam engine. Relatively widespread use of mineral oils appeared in the beginning of the 20th century.
The first mechanism which could be looked upon as a prototype of the rolling bearing mechanism was designed by a Greek engineer by the name of Diades at around 330 b.c. This design constituted the head of a tower used to crumble city walls (drawing no.4).
Rys.4
This construction featured a ram which rested on rollers that moved along running tracks gouged out at its base. The rollers were held by a common bearing cage, powered by ropes tied to its ends which continued over fixed type rollers. The interesting thing about this type of construction is that not only has the way in which modern type bearings work been applied for the first time, it also boasted transfer of movement by way of rolling contact, which is used widely in modern frictional variable-speed transmissions.
The first axial bearing dates back to the late Kaliguli era. Archaeologists have discovered a turntable on a ship dating back to that time (1 a.d.). One of the turntables discovered had turning capability thanks to a set of wheels that it rested on, which were fixed around the circumference of the wheel.
A second turntable featured balls instead of wheels, each one of which was linked to the turntable by means of a king-pin. The third one featured eight wooden truncated cone shaped rollers which were all pivoted. The turntable mechanism consisted of two wooden boards, of which the lower featured a pivot that kept both boards axially aligned. The top board featured eight depressions with round roller elements inside. These elements were held by pivots loosely attached to the top board, limiting their movement to a single axis. Despite the fact that the pivots themselves carried the weight and made true rolling impossible, this is the first noted instance of using ball shaped rolling elements for the purpose of transferring weight. (drawing no.5)
Rys. 5
The turntable mechanisms discovered are early examples of modern ball roller and cone bearings. Even in those early times, it had been noted that it was better to use ball shaped elements instead of roller shaped elements in thrust bearing designs.
From As of the beginning of our era up to the beginning of the Renaissance, No information can be found on the development of rolling bearings. Leonardo da Vinci made use of roller supports in many of his design projects but these were hardly ever put in to practice up until the beginning of the XVIII century (drawing no. 6). He can thus be considered the inventor of the rolling bearing. Leonardo da Vinci has made a drawing of a revolutionary pivot bearing whose originality is exemplified by the changing of sliding resistance into greatly reduced rolling resistance. This idea was to be exploited up to the end of the XIX century in the form of a ball bearing consisting of an external and internal ring with moving balls in between.
Rys. 6.
The oldest example of a rolling bearing comes from the support of a windmill (drawing no.7) which was built in 1780 in Sprowston, England. It consisted of two separate cast iron ball races holding forty iron balls. It is worth noting that the ratio of the ball race furrow and balls was 1,22 and was a bit bigger that that of modern designs, which made it clear that there was an awareness of the need to reduce movement resistance caused by slippage at the point of contact.
Rys. 7
The XIX century saw further improvements in the design of rolling bearings and their increased use in machinery and equipment. But it was the introduction of abrasive machining toward the end of the last century that facilitated the attaining of sufficient hardness and precision of bearing elements. In the beginning, metal balls were produced from steel rods, which were produced manually. This lack of precision led to an uneven spread of weight which resulted in bearing deformation. The turning point in ball machining was the work of a technician and inventor by the name of Friedrich Fischer, the son of Plilippe Moritz Fischer. Friedrich constructed a steel ball machining device, the first bearing bicycle (1853), invented the first fully automated milling machine which used a similar operating method to that of a grinding stone. Fischer's discovery made it possible to machine hardened steel balls � a grinding process that gave them an even shape. Thanks to this innovation Fischer's steel balls triumphantly entered world markets.
2. The present day
Ball bearings could not be applied in all areas. Further research has thus led to the development of cone, rolling and needle bearings.
In 1907, a young Swedish engineer by the name of Sven Wingquist made a sketch in his diary of the first self-aligning bearing. The post World War I period saw the replacement of the slide bearing by anti-friction bearings. This process was further augmented by the appearance of the rolling bearing � at around 1920 - capable of handling huge loads. Soon thereafter, appeared many derivatives like needle bearings, followed by cone bearings. The significant improvement of slide bearings can be assigned to O. Reynolds and N.P. Pietrow, who independently studied the effects of hydrodynamics. The idea behind this is that with the right amount of shaft revolutions, the layer of oil develops antogeneous pressure which lifts the shaft, thus keeping it from coming into contact with the bearing itself. The testing of this effect led to the construction of hydrostatic slide bearings used in low friction characteristics. Further development saw the introduction of hydrostatic slide bearings used in low revolution machines and those equipped with heavy rotors with pressurised oil fed from the outside. This type of technology is usually found in large steam turbines with horizontal axles, water turbines with vertical axles and large industrial centrifuges.
At around 1945, the development of powder metallurgy has led to the development of oilless slide bearings made of porous materials saturated with grease of from ceramet type agglomerates (bronze/graphite) which lasted long when used in small machinery. In high revolution centrifuges as well as gyroscopes, air serves as lubricant (air bearing).
Another widely used innovation is that of hybrid bearings. The traditional way of increasing bearing resistance is achieved through the use of balls that are hollow or low in weight. An alternative to this solution is the coupling of a ball bearing with a hydrostatic bearing. The workload between the two bearings is divided 50:50, resulting in a ten fold increase in the durability of the ball bearing in relation to an unassisted ball bearing working under the same conditions. IN this design, the outer bearing race of the ball bearing is encased in a stationary enclosure. The inner bearing race is mounted to a bearing sleeve which can rotate independently of the shaft.
The bearing production process sees the implementation of many innovations which facilitate production of more precise, faster and cheaper solutions. One such innovation is torque reduction technology, an example of which is the torque bearing, developed for use iln trains. This technology has led to considerable decreases in fuel consumption.
Yet the greatest breakthrough in bearing design occurred with the introduction of computer technology. Computers enable the analysis of all possible aspects of a set of bearings. Virtual bearings created by means of computer aided design can undergo extensive testing without the need to start technological processes. Advanced computer programmes enable quick assignment of virtually any external or internal parameters. This technology was used in the creation of micro bearings used in microelectronics, e.g. hard disks.
Almost up to the end of the XX century, the traditional material from which bearings were manufactured was steel which was modified in order to meet various needs. But the physical characteristics of steel imposed upon the design engineers a specific framework of applications. Key characteristics of steel include heat expansion, high density, corrosion susceptibility, electric and magnetic conductivity and a high friction ratio, even after precise finishing. The material that opened the door to new possibilities, unattainable for bearings turned out to be silicon nitride - a ceramic composite. This material was initially used solely for the creation of rolling elements. Excellent examples are hybrid, high revolution angular ball bearings. Only a couple of years later, design engineers have started designing bearings whose working parts are also made from ceramic materials (ceramic bearings), i.e. high revolution roll-neck bearings. To compare, the ceramic bearing is capable of working at twice the revolution speed of its steel counterpart.