Single direction angular contact thrust ball bearing

Single direction angular contact thrust ball bearing

Single direction angular contact thrust ball bearings are mainly used to support ball screw and nut assemblies in machine tool applications. These bearings have higher axial rigidity and travelling accuracy, with lower friction moment.

Single direction angular contact thrust ball bearings are not separable, fitted with a contact angle of 60°and glass-fiber reinforced nylon 66 cage, which can be filled with large number of balls. Such design features enhance the axial rigidity of these bearings so as to be adapted for fast changes of position radial and axial.

The single direction angular contact thrust ball bearings can only take axial loads in one direction. If such a single bearing couldn’t have enough axial load carrying capacity or should need to take axial loads in both directions, the bearing set can be used instead.

Matched bearing sets

Such bearing sets have been matched before delivery, so that the expected preload and even load distribution in each bearing will be definitely achieved when the bearing set is located and fastened.

Different kinds of matched bearing sets are as bellows:

Marking of bearing sets

On the outside cylindrical surface of a bearing set, there is marking “V” which also indicates the acting direction of axial loads in the bearing set. When axial loads are accommodated in double directions, the direction of the main axial loads should be considered as an indication.

Dimensions

Single row angular contact thrust ball bearings are made in metric or inch dimension. The boundary dimensions of the standard bearings in metric dimensions comply with ISO15, international standards, those inch bearings are manufactured according to customer’s specific requirements. The metric bearings would be preferred by customers.

Tolerances

HRB single row angular contact thrust ball bearings are manufactured to P4 and P2 class tolerances which correspond to those of radial bearings.

Universal bearings

Single row angular contact thrust ball bearings are mainly mounted in pairs in the application of ball screw and nut assemblies. Such HRB universal bearings are very convenient for the paired mounted. And they are supplied as individual bearings for universal matching in sets.

Limiting speed

Values for limiting speeds for oil and grease lubrications listed in the bearing tables are only for individual bearings. For bearing sets, the listed values must be multiplied by the following factors respectively:

– One set with two bearings: 0.8
– One set with three bearings: 0.65
– One set with four bearings: 0.5

Friction

Single row angular contact thrust ball bearings have relatively low friction. The overall frictional moment of bearing sets is obtained by multiplying the frictional moment of the single bearing with the number of bearing in the set. Generally, the starting moment is twice as high as the operating moment.

Axial rigidity and preload

Single row angular contact thrust ball bearings are designed for high rigidity which is obtained from both their internal structure design and preload, given by mounting. The preload levels in bearing sets are divided into three groups: light (A), medium (B), heavy (C), corresponding to three groups of starting moments. Values for the medium are twice as large as those for the light, and for the heavy twice as large as those for the medium. The starting moment is the same as well. Values for medium preload correspondent with starting moment are listed in the following table 1.

Cages

HRB single row angular contact thrust ball bearings have mounted cage of glass-fiber reinforced nylon 66. The cages are normally suitable to work at temperatures -40 upto +120℃, in spite of temporarily high temperatures.

Loads carried by bearing set

Values for basic dynamic and static load ratings given in the bearing tables are only referred to single bearings. Because every bearing in the bearing set can only accommodate axial loads in one direction, the overall axial load for the bearing set must be calculated by multiplying the number of bearings in the given direction in the bearing set with the axial load of the single bearing. For example, in a back-to-back bearing set, there is one bearing to take axial loads in the given direction.

Equivalent dynamic bearing load

For single row bearings and matched bearing sets, the equivalent dynamic bearing load is calculated from the equation:

P = YFa + XFr,                   Fa/Fr ≤ 2.17
P = Fa + 0.92Fr,                 Fa/Fr>2.17

where

P—equivalent dynamic bearing load acting on single bearing or matched bearing set, (N)
Fa—actual axial load, (N)
Fr—actual radial load, (N)
X—calculation factors, shown in the following table2
Y—calculation factors, shown in the following table2

For matched bearing sets, Fa must include the preload.

Equivalent static bearing load

For bearing sets arranged in back-to-back or face-to-face, the equivalent static bearing load is calculated as bellows:

P0 = Fa + 4Fr

where

P0: equivalent static bearing load, acting on single bearing or matched bearing set, N
Fa: actual axial load, (N)
Fr: actual radial load, (N)

Additionally, the equation is also effective for single bearings or tandem bearing pairs when Fr/Fa ≤ 0.25. When 0.4 ≥ Fr/Fa>0.25, a satisfied approximation may be reached.

Lubrication

Single row angular contact thrust ball bearings can be lubricated with either grease or oil. Generally, grease lubrication is preferred because the bearing structure can be simplified with less maintenance. High quality lithium based grease of anti-corrosion are most suitable, at temperatures -30 upto +110℃. About 25 upto 35% of free inner space of bearings is filled with grease.

Accuracy of surrounding parts

HRB single row angular contact thrust ball bearings are manufactured to higher tolerance classes, which can achieve higher rotary accuracy and position accuracy if surrounding parts have the same tolerance classes as the bearings. Consequently, the tolerances are as bellows:


Catalog of HRB Single direction angular contact thrust ball bearings