Product Details

Bearing Type	Size(mm)					Steel Balls Limit Speed(r/min)	Ceramic Balls Limit Speed(r/min)	Weight(kg)≈
Bearing Type	d	D	B	r(min)	r1(min)	Grease Lubrication		Steel Balls	Ceramic Balls
H7006C-2RZ	30	55	13	1.0	0.30	23500	35000	0.110	0.094
H7007C-2RZ	35	62	14	1.0	0.30	20500	31000	0.145	0.134
H7008C-2RZ	40	68	15	1.0	0.30	18500	28000	0.175	0.161
H7009C-2RZ	45	75	16	1.0	0.30	16700	25000	0.245	0.230
H7010C-2RZ	50	80	16	1.0	0.30	15000	23000	0.260	0.240
H7011C-2RZ	55	90	18	1.0	0.30	13800	21000	0.380	0.350
H7012C-2RZ	60	95	18	1.1	0.60	13000	19000	0.410	0.376

Angular Contact Ball Bearing

A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.

The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least three races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling they have a much lower coefficient of friction than if two flat surfaces were sliding against each other.

Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races.

Common designs

There are several common designs of ball bearing, each offering various performance trade-offs. They can be made from many different materials, including: stainless steel, chrome steel, and ceramic (silicon nitride (Si3N4)). A hybrid ball bearing is a bearing with ceramic balls and races of metal.

Angular contact

An angular contact ball bearing uses axially asymmetric races. An axial load passes in a straight line through the bearing, whereas a radial load takes an oblique path that acts to separate the races axially. So the angle of contact on the inner race is the same as that on the outer race. Angular contact bearings better support combined loads (loading in both the radial and axial directions) and the contact angle of the bearing should be matched to the relative proportions of each. The larger the contact angle (typically in the range 10 to 45 degrees), the higher the axial load supported, but the lower the radial load. In high speed applications, such as turbines, jet engines, and dentistry equipment, the centrifugal forces generated by the balls changes the contact angle at the inner and outer race. Ceramics such as silicon nitride are now regularly used in such applications due to their low density (40% of steel). These materials significantly reduce centrifugal force and function well in high temperature environments. They also tend to wear in a similar way to bearing steel—rather than cracking or shattering like glass or porcelain.

Most bicycles use angular-contact bearings in the headsets because the forces on these bearings are in both the radial and axial direction.

Axial

An axial or thrust ball bearing uses side-by-side races. An axial load is transmitted directly through the bearing, while a radial load is poorly supported and tends to separate the races, so that a larger radial load is likely to damage the bearing.

Deep-groove

In a deep-groove radial bearing, the race dimensions are close to the dimensions of the balls that run in it. Deep-groove bearings support higher loads than a shallower groove. Like angular contact bearings, deep-groove bearings support both radial and axial loads, but without a choice of contact angle to allow choice of relative proportion of these load capacities.

Preloaded pairs

The above basic types of bearings are typically applied in a method of preloaded pairs, where two individual bearings are rigidly fastened along a rotating shaft to face each other. This improves the axial runout by taking up (preloading) the necessary slight clearance between the bearing balls and races. Pairing also provides an advantage of evenly distributing the loads, nearly doubling the total load capacity compared to a single bearing. Angular contact bearings are almost always used in opposing pairs: the asymmetric design of each bearing supports axial loads in only one direction, so an opposed pair is required if the application demands support in both directions. The preloading force must be designed and assembled carefully, because it deducts from the axial force capacity of the bearings, and can damage bearings if applied excessively. The pairing mechanism may simply face the bearings together directly, or separate them with a shim, bushing, or shaft feature.


DB The load lines in a pair of bearings by back to back assembly are enlarging from the bearing axis. It can bear axial load in two directions and relative larger moment because of larger angular rigidity.	DF The load lines in a pair of bearings by face to face assembly are convergence toward the bearing axis. It can bear axial load in two directions and smaller moment because of smaller angular rigidity.

DT A pair of bearings by series a ssembly only bear axial load in one direction, but it is able to bear larger axial load related to DB and DF.	TBT The tri-bearing matching TBT or TFT isobtained by increasing the same type of the bearing based on DB or DF There are higher axial and radial rigidity for TBT and TFT, so larger load can be supported.

QBCThe four bearing matching QBC (or QFC) is obtained by matching double set of DB (or DF) bearings. QBT (or QFT) is formed when three bearings are installed in a same direction and another one back (or face) to them.	PBC Divide the five bearings into two groups of three and two bearings respectively, in which the bearings are all installed in the same direction, PBC is formed when the groups match each other by back to back and PFC by face to face. If four bearings are installed in the same direction and another one back (or face) to them, then PBT (or PFT) is formed.