Cylindrical Roller Bearings

★　Product Characteristics

Cylindrical roller takes on line contact with raceway, and the radial load capacity is large. The cylindrical roller bearing can be subject to heavy load and impact load, and be applicable for high-speed rotation.

After improvement of cylindrical roller bearing raceway and rolling element geometry, the cylindrical roller bearing is provided with larger load capacity. The new type structure design of rib and roller end not only enhances the axial rolling element load capacity of the bearing, but also improves the lubricating condition of the contacting area of the roller end and the rib, and the service performance is also enhanced.

This type of bearing is mainly applied on medium-sized and high-capacity motor, generator, gas engine, steam turbine, machine tool main shaft, speed reducer, stevedoring and transporting machine and various industrial machines.

●　Product Classification

Cylindrical roller bearings produced by ZWZ can be divided into the following types:

1. Single-row cylindrical roller bearing
2. Double-row cylindrical roller bearing
3. Four-row cylindrical roller bearing

Single-row Cylindrical Roller Bearing

NUType, NType:
NUtype bearing has double ribs on the outer race, and the outer race, the roller and the holder can separate from the inner race. Ntype bearing has double ribs on the inner race, the inner race, the roller and the holder can separate from the outer race.
NUtype and Ntype bearings allow shaft move relative to housing in a definite range. They can suit relative position change of shaft and housing caused by heat expansion or mounting error, and they are very suitable for free end bearings. They can not limit axial displacement of shaft and housing, and can only be subject to radial load.

NJType and NFType:
NJtype bearing has an outer race with double ribs and an inner race with a single rib.
NFtype bearing has an inner race with double ribs and an outer race with a single rib.
NJtype and NFtype bearings can be subject to definite unidirectional axial load.

NUPType, NH Type:
NUPtype bearing has an outer race with double ribs and an inner race with a single rib and a loose rib. NH type bearing has an outer race with double ribs and an inner race with a single rib and a separate thrust collar. Inner race and outer race can be respectively mounted (with complete rollers and holder), and axial displacement of shaft and housing in two directions is limited in the axial windage bound of the bearing. Except being subject to radial load, the bearings can also be subject to little bidirectional axial load. So they are suitable for fixed end bearing.

NCL…V Type:
The cylindrical roller bearing has an outer race with no rib but double locking collars, and the bearing has no holder.
This type of bearing has no holder, but is provided with many rollers. Compared with other cylindrical roller bearings, the bearing can be subject to larger radial load, but its limit speed is lower. The inner race and the outer race of this type of bearing can not be separated, and they can not be separately mounted, either. But the axial displacement of shaft and housing in two directions can be limited in the axial windage bound.

NB Type:
Cylindrical roller bearing without ribs
There is no rib on the outer race and the inner race. The outer race is provided with oilhole. The inner race, the outer race and the complete rollers can be separately mounted, but axial displacement of bearing and housing can not be limited. Besides, the bearing can not be subject to axial load.

NJ…V Type:
The cylindrical bearing has an inner race with one single rib, but no holder.
This type of bearing has no holder, but it is provide with many rollers. Compared with other cylindrical roller bearings of the same external dimensions, the bearing is provided with larger radial load capacity, but the limit speed is lower. It does not limit axial displacement of shaft or housing, and can not be subject to axial load, either.

NCF…V Type:
A centripetal short cylindrical roller bearing has an outer race with one single rib, but no holder.
This type of bearing has no holder, but it is provided with many rollers. Compared with other cylindrical roller bearings of thee same external dimensions, the bearing can be subject to larger radial load, but its limit speed is lower.
This type of bearing can limit the axial displacement of shaft and housing in two directions in the axial windage bound.

…N Type (bearing with limit slot):
Some of the single-row cylindrical roller bearing is provided with a limit slot on the outer race, and its postposition code is indicated by "N". The bearing is axial located in bearing block by limit slot. Bearing axial tightening in housing bore is simplified. The housing bore can be made into pylome to reduce axial dimension of components.

Double-row Cylindrical Roller Bearing

NN Type:
The inner race is provided with rib, while the outer race is not provided with rib. The outer race and the inner components can be separately mounted, and the axial displacement of shaft and housing is not limited. The bearing can not be subject to axial load. Compared with single-row cylindrical roller bearings of the same radial dimensions, this type of bearing can be subject to larger radial load.
The bearing is characterized in compact structure and small deformation when being subject to load, so it is very applicable for bearing of machine tool shaft.

NN…K Type:
The structure is the same with NN type bearing, but the internal bore is conical, which facilitates the minim adjustment of the radial windage and mounting and dismounting. Most of the machine tool shafts adopt this type of bearing. The bearing is mounted on the conical shaft, and the radial windage is adjusted by the press-in amount of the inner race.

NNU Type, NNU…K Type:
The outer race is provided with rib, while the inner race is not provided with rib. This type of bearing can be divided into two types, namely the bearing with cylindrical bore and the one with conical bore. Axial displacement of shaft or housing is not limited, and the bearing can not be subject to axial load. Compared with single-row cylindrical roller bearings of the same radial dimensions, the bearing can be subject to larger radial load.

NNCF Type:
The inner race is provided with three ribs, while the outer race is provided with one rib, and axial location in one direction can be done. A retainer ring is mounted on one side of a rib on the outer race to make the bearing become one.

NNCL Type:
The inner race is provided with three ribs, while the outer race is provided with no rib. There are limit rings on the two sides, which make the bearing become non-separated bearing.

NNCS Type:
The inner race is provided with three ribs, and the outer race has no rib. There is a middle locking collar in the middle of the outer race, and the bearing becomes non-separated bearing. Definite axial displacement between shaft and bearing block is permitted. And the bearing can be used as free end bearing.

Four-row Cylindrical Roller Bearing

Four-row cylindrical roller bearing can be subject to major radial load and impact load. It is provided with high machining precision, and is applicable for high speed.

Grind the inner raceway surface and the roller surface simultaneously after press the inner race into roller path. This is favorable for enhancing rolling precision, and mounting windage of the bearing can be freely adjusted.

The bearing are mainly applied on the working roll or supporting roll of machines such as cold mill, hot mill and roughing mill etc, it can also be applied on other occasions.

FC： double outer races, single inner race, no rib on the inner race
FCD： double outer races, double inner races, no rib on the inner race
FCDP：double outer races, with only middle rib on and loose rib on the outer race, double inner races, no rib on the inner race.

■　Size Range

The fundamental dimensions of ZWZ cylindrical roller bearings are listed in the dimension datasheet
Inner diameter range:25mm～1900mm
Outer diameter range:52mm～2300mm
Width range: 13mm～400mm

◆　Tolerance

ZWZ produces single-row, double-row and four-row cylindrical roller bearings bellow P4 grade. Meanwhile, ZWZ produces double-row cylindrical roller bearings of special tolerance grade such as SP and UP grade for machine tool main shaft.

▲　Radial Windage

The standard products of ZWZ single-row cylindrical roller bearing are provided with base group radial windage. C3 and C4 group windage can also be supplied.

The standard products of ZWZ double-row cylindrical roller bearing are provided with C1 group windage. Cylindrical bore bearing can offer C2 and C3 group windage, and conical bore bearing can offer C2 group windage.

The standard products of ZWZ four-row cylindrical roller bearing are provided with C3 group windage, and products of other windage group can be offered at the same time.

Please refer to preface table for standard windage value. Bearing whose radial windage is greater or less than standard value can be produced according to user's requirement.

★　Holder

Single-row cylindrical roller bearing mainly adopts sweeping entity holder, stamping holder and nylon holder etc.

Double-row cylindrical roller bearing mainly adopts sweeping brass holder, and sometimes nylon holder is offered.

Four-row cylindrical roller bearing mainly adopts sweeping brass holder, and bearing of large dimension should adopt sweeping entity mainstay holder.

Holder code is marked as follow:
1. When adopting stamping holder, the postposition code of the holder is marked as J; if various stamping holder structures are not identical, user J, J1, and J2… in turn to indicate.
2. When adopting groove holder, the postposition code is marked as CJ;
3. When adopting brass entity holder, the postposition code is marked as M;
4. When bearing outer diameter D>400mm, steel entity holder is adopted, and the postposition code is not marked. But when it is inner leading or outer leading, corresponding postposition code of the holder material and the leading type should be simultaneously marked. (outer leading is A, and inner leading is B).

Double-row cylindrical roller bearing adopts brass entity holder and should not be marked.

■　Equivalent Moving Load

When being subject to radial load, P = Fr

★　Equivalent Dead Load

P0r= Fr
When the inner race and the outer race of the bearing are all provided with ribs or retainer rings, the bearing will be subject to radial load and be subject to definite axial load at the same time. The axial load capacity at the moment is determined by roller end situation, rib load capacity, lubricating condition and rotate speed etc.