文档介绍：LESSON FOUR FOUNDATIONS OF MACHINE DESIGN (PART l)
Bearings With Rolling Contact
In bearings with rolling contact, the shaft is directly or indirectly supported by rolling elements, such as balls, cylindrical or conical rollers, or needles (., cylindrical rollers with a high L/D ratio). The occasionally encountered name " antifriction bearings" suggests that this type has little or no friction. This is erroneous, since the friction is merely of another nature than in journal bearings. In bearings with rolling contact, friction losses are caused by the elastic deformation of the surfaces in rolling contact, sliding friction of rolling elements with cages, retaining rings and seals, or with one another, and also by some shear of lubricant.
conical roller
圆锥滚柱
needle 滚针
cylindrical
roller
圆柱滚柱
antifriction
bearing
减摩轴承
cage 保持架
retaining ring
档圈
bearing 轴承
journal bearing
颈轴承
滑动轴承
Characteristics
l. Ball bearings have rolling elements in the form of balls, which in all but the most inexpensive types are held in cages, separators, or retainers, and inner and outer grooved races.
2. Roller bearings have mainly cylindrical, conical, or barrel-shaped rollers instead of balls, but are otherwise quite similar to ball bearings.
3. Needle bearings usually have neither an inner race nor a cage. The needles are retained by integral flanges on the outer race. Transitional types between roller and needle bearings are found in many catalogs.
Bearings with rolling contact have no slipstick effect, low starting torque and running friction, and unlike as in journal bearings, the coefficient of friction varies little with load or speed. Low starting torque is of great advantage in railroad cars, and the railroad industry has given the main impetus for the development of mass-produced roller bearings in the past, mainly for this reason.
These bearings may take both radial and axial loads (depending upon the type), and need less space axially but more radially (excep