Roller bearing - free motion between moving and fixed parts
The roller bearing is a special kind of rolling-element bearing which is able to carry great loads at a minimum amount of weight. It consists of two so-called races - an inner as well as an outer race - that are filled with cylinders called rollers. These highly robust rollers are specially designed to reduce friction and other forces that are applied to mechanical devices in which the part is used. Depending on the manufacturer, the parts come in a great variety of designs, sizes and series. Additional types of rolling-element bearings include what are commonly known as ball bearings.
Which type of roller bearing is which?
Different designs incorporate a wide range of attributes and possibilities. In general, races and other parts of rolling-element components are made of plain steel, but materials such as plastics, glass and ceramics are also put to use during the manufacturing process. They differ, however, in specifications like width, bore as well as outside diameter, size and weight. Apart from the general structure, roller bearings are also diverse in design and can thus be used for a multitude of tasks. There are five different kinds of roller bearings:
Needle and toroidal
Based on the components' manufacturer, each series is available in different sizes and weights, so it can readily be used as a crucial component inside a multitude of machines of different settings and sizes. In order to maximize performance and other characteristics of these machine elements, combinations of various types have been made possible by most manufacturers.
Almost every supplier provides the cylindrical roller bearing. This series is mostly manufactured as a single-row type with a surrounding cage, but is also available with double or multi-row bearings. The assortment also includes a choice of full or split complement parts without a cage. Interchangeable components allow for better maintenance.
While bearings fitted with a cage can handle heavy radial loads and rapid acceleration, the full complement type is equipped with a maximum number of rollers, which makes them suitable for very heavy radial loads.
An exact fitting is crucial for optimum performance and durability.
While other types - like the spherical system - are able to accommodate a faulty fitting, cylindrical bearings might suffer adverse effects in performance and capacity if there is a misalignment inside the machine. Therefore, an exact fitting is required to ensure high performance and long service life from these mechanical parts.
Two rows of rollers are fitted into a spherical bearing. The centre point on this special kind of machine element is located at the axis of the outer race. This makes them insensitive to misalignment, because the elements align themselves due to the nature of their form. The spherical system is suitable for accommodating heavy radial and axial loads in both directions.
Mostly employed in measuring instruments and watches, the sophisticated gear bearing cleverly combines features of roller bearings with those of epicyclical gear train technology. By fitting bevelled bearing gearwheels - consisting of alternating rollers and gearwheels with equal diameters - inside the construction, sliding friction during motion is reduced to a minimum
A conical design is used in tapered machine elements. They accommodate both radial and axial loads due to a greater contact area that comes with the dimension and form of rollers and races.
Tapered bearing systems can be found on most wheeled vehicles, where they are able to carry high loads.
Needle and toroidal
The needle roller bearing uses small, very thin cylindrical roller elements. This compact device consists of a cage that holds the needle-like roller components. The length of these components is supposed to be four times their diameter to qualify as a regular needle bearing. This is also the difference between a needle and a common roller bearing.
Similar to the needle elements in its appearance, the toroidal series is a special kind of machine component. Since the radius of the outer ring is much larger than that of the spherical series, toroidal components are able to accommodate both angular misalignment and axial displacement.
Know-how and experience are the best tools for innovation
Systems that rely on devices fitted with roller components benefit from a variety of advantages. No lubrication such as oil is needed, while only a minimum amount of friction occurs on each part. High durability is the product of cutting-edge industrial science.
Extremely tight tolerances in both dimension and form maximize load and service life.
The performance of roller bearing components is influenced by the geometry of:
These features combined with meticulous maintenance on a regular basis ensure long durability and steady performance. But which industrial areas are these sophisticated parts usually used in?
Construction/general usage in machines that operate with high torques
Automotive (e.g. gearboxes), material handling, mining and construction, etc.
Measuring instruments, watches
Automotive (e.g. compressors and transmissions)
Roller bearing manufacturers devise their parts according to extremely tight tolerances in terms of both dimension and form. Load and service life are maximized in the process by shaping each roller bearing exactly the same and hence manufacturing virtually identical parts.