Cylindrical Roller Bearings

Did You Know? Earthquake-Proof Buildings The new San Francisco International Airport uses many advanced building technologies to help it withstand earthquakes. One of these technologies involves giant ball bearings. The 267 columns that support the weight of the airport each ride on a 5-foot-diameter (1.5-meter) steel ball bearing. The ball rests in a concave base that is connected to the ground. In the event of an earthquake, the ground can move 20 inches (51 cm) in any direction. The columns that rest on the balls move somewhat less than this as they roll around in their bases, which helps isolate the building from the motion of the ground. When the earthquake is over, gravity pulls the columns back to the center of their bases.

Cylindrical roller bearings use rollers for rolling elements, and therefore has a high load capacity. The rollers are guided by ribs on either the inner or outer ring, therefore these bearings are also suitable for high speed applications. The inner and outer rings can be separated to facilitate assembly, and both can be fit with shaft or housing tightly.

If there is no ribs, either the inner or the outer ring can move freely in the axial direction. Cylindrical roller bearings are therefore ideal to be used as so-called "free side bearings" that absorb shaft expansion.

Physical Characteristics

Although the rolling elements in cylindrical roller bearings are called "cylindrical," they are not true cylinders. True cylinders would produce stress concentrations at the ends of the roller-race contact, resulting in high wear and high sensitivity to misalignment. Instead, rollers are usually crowned or end relieved.

You will find various types and characteristics of cylindrical roller bearings in the following tables:
Click here - Single row cylindrical roller bearing types and characteristics
Click here - Non-standard type cylindrical roller bearing characteristics

Application Of Cylindrical Roller Bearings

Cylindrical roller bearings are used in power generation, oilfield, mining and aggregate processing, gear drives, rolling mills, machine tools, transmissions, vibration machines and as wheelset bearings for rail vehicles.

Types Of Cylindrical Roller Bearings

There are three basic types of cylindrical roller bearings:

• Single or Double Row Bearings
• Full Complement Cylindrical Roller Bearings
• Crossed Cylindrical Roller Bearing

Buying Tips Consider the followings before you go and shop for Cylindrical Roller Bearings: Radial load capacity Dimension series and sizes Stress distribution in the contact zones Roller materials Operational cost & lubrications Allowable axial load

Single Row Bearings
The rollers of single row cylindrical roller bearings with cage are guided on one of the bearing rings. The bearing ring with integral flanges and the roller and cage assembly can be withdrawn from the other ring. This allows easy mounting and dismounting. They have high radial load carrying capacity at high speeds. EC type bearings have larger load carrying capacity. Depending on the type and location of the flanges, they are of different types:

1. Two integral flanges on the outer ring only.
2. Two integral flanges on the inner ring only.
3. Two integral flanges on the outer ring and one on the inner.
4. Two integral flanges on the outer ring, one integral and one loose on the inner.

Full Complement Cylindrical Roller Bearings
They incorporate maximum number of rollers and low sectional height as compared to width allowing very high load carrying capacity. They are suitable for very high radial loads. The rollers are in direct contact with each other and slide against each other while rolling.

The single row bearings are developed as standard single row designs they have two integral flanges on the inner ring and one on the outer. This helps locate the shaft in one direction. They are suitable for heavily loaded slow speed applications.

The double row bearings have an annular groove for lubrication. All different types of double row cylindrical roller bearings differ in the number of flanges in the outer ring.


Crossed Cylindrical Roller Bearings
The raceways in the inner and the outer rings of the crossed cylindrical roller bearings are inclined at an angle of 45 °. The diameter of the rollers is larger than the length. They provide stiff bearing arrangements and can carry very heavy loads. They require minimum of space and require very less space. They can accommodate radial, axial and moment loads. Their surface finish maximizes lubricant film formation and optimizes rolling motion of the rollers.

Apart from the standard single row they are available in other:

1. Single or double row bearings in full compliment or caged forms
2. Bearings with clearance and preload
3. Bearings with integral gears for bolt attachments in bearing rings
4. Bearings with integral seals.

Cylindrical Roller Bearings Specifications & Standards

Standard cage types
The following table shows the standard cage types for cylindrical roller bearings:

Dimensions - The dimensions are as per the ISO recommendations

Allowable misalignment - They are designed to adjust to limited angular misalignments of the inner ring with respect to the outer to a few minutes of the arc. The elastic deformation in the crossed cylindrical type is minimal because of large number of rollers and line of contact between them.

Although values vary somewhat depending on bearing type and internal specifications, under general load conditions, to avoid the occurrence of edge loading, allowable misalignments have been set as follows:

Bearing width series 0 or 1: ………0.001 rad (3.5') Bearing width series 2: ………0.0005 rad (1.5') Double row cylindrical roller bearings ………0.0005 rad (1.5')

Tolerance - They are usually meant for normal

Internal Clearance - For radial internal clearance of single and double row, normal is taken as standard and the axial clearance varies.

Bore	Radial internal clearance
Diameter		C2		Normal		C3		C4
over	incl.	min	max	min	max	min	max	min	max
mm
-	24	0	25	20	45	35	60	50	75
24	30	0	25	20	45	35	60	50	75
30	40	5	30	25	50	45	70	60	85
40	50	5	35	30	60	50	80	70	100
50	65	10	40	40	70	60	90	80	110
65	80	10	45	40	75	65	100	90	125
80	100	15	50	50	85	75	110	105	140
100	120	15	55	50	90	85	125	125	165
120	140	15	60	60	105	100	145	145	190
140	160	20	70	70	120	115	165	165	215
160	180	25	75	75	125	120	170	170	220
180	200	35	90	90	145	140	195	195	250
200	225	45	105	105	165	160	220	220	280
225	250	45	110	110	175	170	235	235	300
250	280	55	125	125	195	190	260	260	330
280	315	55	130	130	205	200	275	275	350
315	355	65	145	145	225	225	305	30	385
355	400	100	190	190	280	280	370	370	460
400	450	110	210	210	310	310	410	410	510
450	500	110	220	220	330	330	440	440	550
500	560	120	240	240	360	360	480	480	600
560	630	140	260	260	380	380	500	500	620
630	710	145	285	285	425	425	565	565	705
710	800	150	310	310	470	470	630	630	790

Normal radial internal clearance is taken as standard in full compliment cylindrical roller ball bearings.

Normal radial internal clearance is taken as standard in crossed cylindrical roller ball bearings.

Axial internal internal clearence of bearings of series 1
Bore daimeter	NUP2	NJ2+HJ	NUP3	NJ 3 + HJ	NUP 4	NJ4 + HJ	NUP 22	NJ22+HJ	NUP 23	NJ 23 + HJ
d	min max	min max	min max	min max	min max	min max	min max	min max	min max	min max
mm
15	-	42 165	-		-	-	-	-	-	-
17	37 140	42 165	37 140	42 165	-	-	37 140	42 165	47 155	52 183
20	37 140	42 165	37 140	42 165	-	-	47 155	52 185	47 155	52 183
25	37 140	42 165	47 155	42 165	-	-	47 155	52 185	47 155	52 183
30	37 140	42 165	47 155	52 185	-	60 200	47 155	52 185	47 155	52 183
35	47 155	52 185	47 155	52 185	55 155	60 200	47 155	52 185	62 180	72 215
40	47 155	52 185	47 155	52 185	55 155	60 200	47 155	52 185	62 180	72 215
45	47 155	52 185	47 155	52 185	55 155	60 200	47 155	52 185	62 180	72 215
50	47 155	52 185	47 155	52 185	70 185	80 235	47 155	52 185	62 180	72 215
55	47 155	52 185	47 155	52 185	70 185	80 235	47 155	52 185	62 180	72 215
60	47 155	52 185	62 180	72 215	70 185	80 235	62 180	72 215	87 230	102 275
65	47 155	52 185	62 180	72 215	70 185	80 235	62 180	72 215	87 230	102 275
70	47 155	52 185	62 180	72 215	70 185	80 235	62 180	72 215	87 230	102 275
75	47 155	52 185	62 180	72 215	70 185	80 235	62 180	72 215	87 230	102 275
80	47 155	52 185	62 180	72 215	-	80 235	62 180	72 215	87 230	102 275
85	62 180	72 215	62 180	72 215	-	110 290	62 180	72 215	87 230	102 275
90	62 180	72 215	62 180	72 215	-	110 290	62 180	72 215	87 230	102 275
95	62 180	72 215	62 180	72 215	-	110 290	62 180	72 215	87 230	140 375
100	62 180	72 215	87 230	102 275	-	110 290	87 230	102 275	120 315	140 375
105	62 180	72 215	-	102 275	-	110 290	87 230	102 275	120 315	140 375
110	62 180	72 215	87 230	102 275	-	110 290	87 230	102 275	120 315	140 375
120	62 180	72 215	87 230	102 275	-	110 290	87 230	102 275	120 315	140 375
130	62 180	72 215	87 230	102 275	-	-	87 230	102 275	120 315	140 375
140	62 180	72 215	87 230	102 275	-	-	87 230	102 275	120 315	140 375
150	62 180	72 215	87 230	102 275	-	-	87 230	102 275	120 315	140 375
160	87 180	102 275	-	110 310	-	-	-	140 375	-	140 375
170	87 230	102 275	-	-	-	-	-	140 375	-	-
180	87 230	102 275	-	-	-	-	-	140 375	-	-
190	87 230	102 275	-	-	-	-	-	-	-	-
200	87 230	102 275	-	-	-	-	-	-	-	-
220	95 230	110 290	-	-	-	-	-	-	-	-
240	-	110 310	-	-	-	-	-	-	-	-
260	-	110 310	-	-	-	-	-	-	-	-
280	-	110 310	-	-	-	-	-	-	-	-

Minimum Load - For satisfactory operation, the bearings must be subjected to the minimum load that is calculated by:

Radial Bearings :
Deep Groove Ball Bearings | Self Aligning Ball Bearings | Angular Contact Ball Bearings | Cylindrical Roller Bearings | Needle Roller Bearings | Spherical Roller Bearings | Taper Roller Bearings