What Bearing Should You Use for Heavy Radial Loads, Electric Motors and Gearboxes? A Complete Guide to Cylindrical Roller Bearings

Cylindrical roller bearings are radial rolling bearings with rollers shaped like cylinders. The contact between the rollers and raceways is line contact, which provides 2–3 times higher radial load capacity compared to the point contact of deep groove ball bearings, making them the preferred solution for heavy radial load conditions. Cylindrical roller bearings mainly bear radial loads. The friction between the rolling elements and the ring edges is low, making them suitable for high-speed rotation, with limiting speeds close to those of deep groove ball bearings. Based on whether the rings have flanges, single-row cylindrical roller bearings can be divided into NU, N, NJ, NUP, NF types, and double-row cylindrical roller bearings into NNU, NN types. These bearings have separable inner and outer rings, which makes installation and maintenance convenient. The NU type has fixed flanges on both sides of the outer ring and no flanges on the inner ring, allowing slight axial displacement of the shaft relative to the bearing housing. It is suitable for free-end applications such as gearbox support ends and non-driving ends of motors. The NJ type has fixed flanges on both sides of the outer ring and one flange on the inner ring, capable of carrying unidirectional axial loads. It is usually paired with deep groove ball bearings or angular contact ball bearings and is suitable for fixed ends of gearboxes and driving ends of large motors. The NUP type adds a separable flat flange on the basis of the NJ type, allowing bidirectional axial positioning. It is suitable for applications requiring precise positioning and capable of bearing axial loads in both directions. The N type has no flanges on the outer ring and double flanges on the inner ring, mainly used in special cases requiring axial free displacement. Cylindrical roller bearings are generally used only to bear radial loads. Compared with deep groove ball bearings of the same size, they have higher radial load capacity. The limiting speed is close to that of deep groove ball bearings, but they require higher precision in shaft and housing bore processing, allowing very small misalignment (2°–4°) between the inner and outer rings. If axial loads must be borne, they can only be used together with other types of bearings that carry axial loads. Why choose cylindrical roller bearings? First, extremely high radial load capacity: the line contact design provides a load capacity far higher than that of ball bearings of the same size, making it the preferred solution for heavy radial load conditions. Second, high limiting speed: precision fit between the rollers and the cage allows speeds up to 80%–100% of deep groove ball bearings. Third, low friction coefficient: optimized raceway geometry and cage guidance reduce operational friction and heat generation. Fourth, separable structure: most cylindrical roller bearings have separable inner and outer rings, making installation and maintenance more convenient. Fifth, the clearance is adjustable and the structure is flexible. Single-row bearings can have their clearance adjusted during installation. NU/N types are suitable for the free end, while NJ/NUP types are suitable for the fixed end, covering a variety of bearing configuration needs. Cylindrical roller bearings are mainly used in: the drive and non-drive end support of medium and large motors, locomotives, machine tool spindles, internal combustion engines, generators, and gas turbines; the input and output shaft support of reducers, the fixed and support ends of gearboxes; four-row cylindrical roller bearings in rolling mills for large cold and hot rolling machines; support for crushers and vibrating screens in vibratory screens, lifting and transportation machinery, construction machinery, port machinery, and mining machinery; steel and metallurgical equipment, wind power equipment, industrial robots; as well as precision fields such as textiles, printing, and aerospace. Those who need cylindrical roller bearings include: OEM procurement for medium and large motor manufacturers, reducer and gearbox manufacturers, metallurgical rolling mill equipment manufacturers, mining equipment manufacturers and maintenance teams, machine tool manufacturers, construction machinery and railway equipment manufacturers, industrial equipment dealers and bearing stockists, equipment maintenance and replacement procurement teams, and overseas EPC contractors. In which situations should cylindrical roller bearings be chosen or replaced? When equipment needs to withstand large pure radial loads and deep groove ball bearings are insufficient; when reducers and gearboxes require a combination of free-end and fixed-end bearing configurations; when medium and large motors require bearings with high radial load capacity and high limit speed; when rolling mills and vibrating screens need reliable support under heavy-load impact conditions; when worn bearings cause increased vibration and abnormal temperature rise and need replacement; when equipment requires separable structures for convenient installation and maintenance; when export projects require bearings interchangeable with ISO standards. How to choose cylindrical roller bearings? First, determine the type of load. Cylindrical roller bearings are mainly used to withstand radial loads. NU/N types cannot bear axial loads, NJ types can bear unidirectional axial loads, and NUP types can bear bidirectional axial loads. Choose the appropriate type according to the load direction. Second, determine the structural form: single-row for conventional radial loads, double-row NN/NNU types for high-rigidity machine tool spindles, four-row for rolling mills and other ultra-high radial load applications. Step three: Determine the size series. Select the NU200/NU300/NU2200/NU2300 series according to the shaft diameter and inner diameter code; Step four: Select the clearance. For standard conditions, choose CN; for high temperature or interference fit, choose C3/C4; Step five: Determine the accuracy grade. For general machinery, choose P0; for precision machine tools and high-speed motors, choose P6/P5/P4; Step six: Confirm the cage material. The standard is stamped steel or Nylon 66; for heavy load conditions, choose a solid brass cage or PEEK cage; Step seven: Confirm the mounting fit. The inner ring of NU/N type with the shaft usually uses k6/m6 fit, while the locating end of NJ/NUP type requires attention to axial fixation; Step eight: Confirm the lubrication method, either grease or oil lubrication, selected according to speed and working temperature.

Model example: `NU206EM`, meaning NU type cylindrical roller bearing, 2 for size series (light narrow), 06 for inner diameter code (06×5=30mm), E for reinforced design, M for machined brass cage.

Main models and parameters of cylindrical roller bearings (example)

Model	Type	Inner diameter d mm	Outer diameter D mm	Width B mm	Rated dynamic load Cr kN	Rated static load C0 kN	Limiting speed rpm (grease lubrication)	Limiting speed rpm (oil lubrication)	Weight kg
NU204	NU	20	47	14	16.0	13.6	18000	22000	0.110
NU205	NU	25	52	15	18.6	16.0	16000	20000	0.140
NU206	NU	30	62	16	24.0	21.0	14000	17000	0.200
NU207	NU	35	72	17	30.8	27.0	12000	15000	0.290
NU208	NU	40	80	18	36.5	32.5	10000	13000	0.380
NU209	NU	45	85	19	41.5	38.0	9500	12000	0.430
NU210	NU	50	90	20	46.5	43.0	9000	11000	0.490
NU211	NU	55	100	21	57.0	53.0	8500	10000	0.660
NU212	NU	60	110	22	68.0	63.0	7500	9000	0.850
NU213	NU	65	120	23	78.0	73.0	7000	8500	1.050
NU214	NU	70	125	24	84.0	80.0	6700	8000	1.150
NU215	NU	75	130	25	90.0	86.0	6300	7500	1.250
NU216	NU	80	140	26	102	98.0	6000	7000	1.550
NU217	NU	85	150	28	118	115	5600	6700	1.920
NU218	NU	90	160	30	135	132	5300	6300	2.360
NU219	NU	95	170	32	152	150	5000	6000	2.870
NU220	NU	100	180	34	170	168	4800	5600	3.420
NU306	NU	30	72	19	32.0	26.5	12000	15000	0.310
NU308	NU	40	90	23	52.0	45.0	9000	11000	0.620
NU310	NU	50	110	27	75.0	67.0	7000	8500	1.080
NU312	NU	60	130	31	102	93.0	6000	7000	1.720
NU314	NU	70	150	35	135	125	5300	6300	2.650
NU316	NU	80	170	39	168	158	4500	5600	3.850
NJ206	NJ	30	62	16	24.0	21.0	14000	17000	0.210
NJ210	NJ	50	90	20	46.5	43.0	9000	11000	0.500
NJ214	NJ	70	125	24	84.0	80.0	6700	8000	1.180
NJ220	NJ	100	180	34	170	168	4800	5600	3.500
NUP206	NUP	30	62	16	24.0	21.0	14000	17000	0.215
NUP210	NUP	50	90	20	46.5	43.0	9000	11000	0.510
NUP214	NUP	70	125	24	84.0	80.0	6700	8000	1.200
NUP2224ECML	NUP	120	215	58	520	630	2200	3000	9.500
NUP2328	NUP	140	300	102	920	1250	1800	2200	36.8

*Data source: General cylindrical roller bearing size parameter table, actual product samples prevail. NU204–NU220 belong to the NU200 series light narrow series, NU306–NU316 belong to the NU300 series medium narrow series. NUP2224ECML has a basic dynamic load rating C of 520,000 N, basic static load rating C0 of 630,000 N, grease lubrication speed 2,200 r/min, oil lubrication speed 3,000 r/min, weight 9.5 kg. NUP2328 has a basic dynamic load rating of 920,000 N, basic static load rating 1,250,000 N, grease lubrication speed 1,800 r/min, oil lubrication speed 2,200 r/min, weight 36.8 kg.*

General technical parameters table

Parameters	Specifications
Type	Cylindrical Roller Bearing (Single Row/Double Row/Four Row)
Structure type	NU (outer rim double flange, inner ring without flange) / N (inner ring double flange, outer ring without flange) / NJ (outer ring double flange, inner ring single flange) / NUP (NJ + flat flange) / NF (outer ring single flange) / NN/NNU (dual row)
Inner diameter range	20–600mm (Standard Series); Larger sizes can be customized
Outer diameter range	47–730mm
Size Series	NU200/NU300/NU2200/NU2300/NJ200/NJ300/NUP200/NUP300, etc
Standard material	GCr15 high-carbon chromium bearing steel (optional GCr15SiMn, GCr18Mo, G2Cr2Ni4A)
Cage	Stamped steel plate (standard); Nylon 66 (TVP2); Machined brass (M/M1); PEEK (high-speed type)
Accuracy grade	P0 (Standard Group); Optional P6, P5, P4, P2
Clearance level	CN (standard clearance); Optional options include C2 (less than standard), C3 (greater than standard), C4, and C5
Sealing type	Open type (standard); Optional ZZ dust cover and 2RS rubber seal
Lubrication method	Grease lubrication/oil lubrication
Permitted tilt angle	2°–4′ (2°–4 minutes, i.e., minimal tilt)
Operating temperature	-30°C to +150°C (standard); High-temperature models can be even higher
Environmental compliance	RoHS/REACH compliance

Reference for Supporting Applications (Example)

Application scenarios	Recommended Structure Type	Recommended Series	Typical Model	Key Requirements
Large and Medium Motor Drive End	NJ/NUP (Locating End)	NJ200/NUP200	NJ210/NUP210	Unidirectional/Bidirectional Axial Location
Large and Medium Motor Non-Drive End	NU/N (Free End)	NU200/NU300	NU210/NU310	Axial Free Displacement Compensation
Reducer Input Shaft	NJ/NUP + NU Combination	NJ200/NU200	NJ206+NU206	Locating End + Free End Configuration
Reducer Output Shaft	NU/NJ (Heavy Load)	NU300/NJ300	NU312/NJ312	High Radial Load
Rolling Mill (Four-Row)	Four-Row Cylindrical Roller	FC Series	FC4054170	Ultra-High Radial Load
Machine Tool Spindle	Double-Row NN/NNU	NN3000/NNU4900	NN3016	High Rigidity, High Precision
Vibrating Screen	NU/NJ (Heavy Load)	NU300/NJ300	NU316/NJ316	Shock Resistant, Wear-Resistant
Mining Crusher	NU/NJ (Heavy Load)	NU2200/NU2300	NU2220	High Radial Load, Shock Resistant
Railway Locomotive	NU/NJ	NU200/NJ200	NU214/NJ214	High Reliability, Long Life

The above are examples; actual selection must be comprehensively calculated according to bearing load, speed, operating temperature, and life requirements.

Dimension Diagram Placeholder: `[Image: /images/cylindrical-roller-bearing-dimension-drawing.webp]`

Material Table

Components	Standard material	Optional Materials	Description
Inner ring, outer ring, rolling element	GCr15 high carbon chromium bearing steel	GCr15SiMn、GCr18Mo、G20Cr2Ni4A	GCr15 is industry standard, high load and fatigue resistance
Cage (standard)	Stamped steel plate	Nylon 66 (TVP2)	Commonly used in small and medium sizes
Cage (heavy duty)	Machined brass (M/M1)	PEEK	Brass is suitable for impact load and high vibration conditions
Cage (high speed)	Machined brass	PEEK	PEEK is suitable for high speed, high rigidity applications
Seal (ZZ)	Metal dust cover	—	Blocks larger particles
Seal (2RS)	Nitrile rubber	Fluorine rubber	Contact seal, dust and water resistant
Lubricating grease	High-quality lithium-based grease	High temperature grease, extreme pressure grease	Select open bearings according to working conditions

Installation fit and clearance selection table

Working conditions	Shaft tolerance	Housing bore tolerance	Recommended clearance	Description
Light load, inner ring rotation	k6	H7	CN	Suitable for motors, pumps
Normal load, inner ring rotation	m5/m6	H7	CN	Commonly used for gear reducers, gearboxes
Heavy load or impact load	n6/p6	K7	C3/C4	Large interference fit, C3/C4 compensation required
High temperature conditions	Appropriately increase interference	—	C3/C4	High temperature causes clearance reduction
High-precision operation (machine tool spindle)	IT5	IT6	CN/C3	High rotation accuracy required
Free End (NU/N Type)	Proper fit with the shaft	Proper fit with the housing bore	CN/C3	Allows axial displacement

Key points for installation inspection: Cylindrical roller bearings are separable structures, and the inner and outer rings can be installed separately. The installation environment should be kept clean to prevent dust and foreign objects from entering; use dedicated installation tools, and never strike the bearing directly with a hammer; for NU/N type free end bearings, either the inner ring or the outer ring must be able to accommodate changes in the shaft and housing length, allowing axial movement. Only N and NU type cylindrical roller bearings can move internally; for NJ/NUP type locating ends, axial fixation must be ensured, usually paired with deep groove ball bearings or angular contact ball bearings to withstand axial loads; after installation, check whether the bearing rotates smoothly and whether there is any sticking or abnormal sound; double-row cylindrical roller bearings (NN/NNU type) have higher requirements for shaft and housing bore machining and must ensure that the fit accuracy meets the requirements.

Application Scenario Table

Industry	Application	Recommended Configuration	Key Requirements
Medium and Large Motors	Drive End and Non-Drive End Support	NJ/NUP (Locating End) + NU (Free End)	High radial load, high limit speed
Gearboxes for Reducers	Input Shaft, Output Shaft, Intermediate Shaft	NJ/NUP + NU Combination	Locating End + Free End Configuration, Radial Load
Metallurgical Rolling Mill	Large Cold and Hot Rolling Mills	Four-Row Cylindrical Roller Bearings (FC Series)	Extremely high radial load, low-speed heavy load
Machine Tools	Spindle, Feed System	Double-Row NN/NNU Type	High rigidity, high precision P5/P4
Mining Machinery	Crushers, Vibrating Screens, Hoists	NU/NJ Heavy-Duty Series	Impact-resistant, wear-resistant, high load-bearing
Construction machinery	Cranes, excavators, loaders	NU/NJ series	Impact-resistant, dustproof
Railway vehicles	Axle boxes, wheelset supports	NU/NJ series	High Reliability, Long Life
Wind power equipment	Main shaft, gearbox	Double-row / four-row cylindrical roller	High load-bearing, long lifespan
Industrial robots	Joint reducers	High-precision cylindrical rollers	High rigidity, low friction

Note: Cylindrical roller bearings generally only handle radial loads. NU/N type cannot bear axial loads, NJ type can bear unidirectional axial loads, and NUP type can bear bidirectional axial loads. If large axial loads need to be supported, other types of bearings (such as deep groove ball bearings or angular contact ball bearings) must be used simultaneously to handle the axial load. Cylindrical roller bearings allow only a slight tilt of the inner ring axis relative to the outer ring axis (2°–4′), requiring high processing accuracy for shafts and housing holes.

Selection considerations (compared to deep groove ball bearings and tapered roller bearings): The core difference between cylindrical roller bearings and deep groove ball bearings or tapered roller bearings lies inthe type and capacity of load-bearing.. Deep groove ball bearings mainly bear radial loads and certain bidirectional axial loads, feature point contact design, have the highest limiting speed, and lowest friction torque, suitable for light-load high-speed general applications; tapered roller bearings have line contact between rollers and raceways, can bear heavier combined radial and axial loads, the larger the contact angle the higher the axial load capacity, suitable for heavy-load conditions that require bearing both radial and axial loads, but have relatively lower limiting speed and are usually installed in pairs; cylindrical roller bearings have line contact between rollers and raceways, radial load capacity is 2–3 times higher than deep groove ball bearings of the same size, limiting speed is close to that of deep groove ball bearings, mainly bear radial loads, NU/N types cannot bear axial loads, NJ/NUP types can bear unidirectional/bidirectional axial loads, suitable for heavy radial load conditions where certain limiting speed is required. When selecting, prioritize cylindrical roller bearings for pure heavy radial loads, tapered roller bearings for combined heavy radial and axial loads, and deep groove ball bearings for light-load high-speed.

## Technical FAQ

1. What is a cylindrical roller bearing?

A cylindrical roller bearing is a radial rolling bearing with cylindrical rollers as rolling elements, with line contact between rollers and raceways, mainly bearing radial loads. Its radial load capacity is 2–3 times higher than that of a deep groove ball bearing of the same size, suitable for heavy radial load conditions.

2. How to read the model of a cylindrical roller bearing?

The model consists of the structural type code + dimension series + inner diameter code. Example: NU206, where NU is the structural type (outer ring with double flanges, inner ring without flange), 2 is the dimension series (light/narrow), 06 is the inner diameter code (06×5=30mm). The NJ type can bear unidirectional axial loads, the NUP type can bear bidirectional axial loads, and the N type is used for applications with axial free displacement.

3. What are the main structural types of cylindrical roller bearings?

NU type (outer ring with double flanges, inner ring without flange, free end), N type (inner ring with double flanges, outer ring without flange, free end), NJ type (outer ring with double flanges, inner ring with single flange, unidirectional axial load), NUP type (NJ type + flat flange, bidirectional axial positioning), NF type (outer ring with single flange), and double row NN/NNU types.

4. What are the differences between NU, NJ, and NUP types?

NU type has a double flange on the outer ring and no flange on the inner ring, cannot bear axial load, allows axial displacement of the shaft within the bearing, used for the free end; NJ type has a double flange on the outer ring and a single flange on the inner ring, can bear unidirectional axial load, used for the locating end; NUP type is based on NJ type with an added flat retaining ring, can bear bidirectional axial load, used for the fully locating end.

5. Can cylindrical roller bearings bear axial load?

Cylindrical roller bearings are generally used to bear radial load only. NU/N types cannot bear axial load; NJ type can bear unidirectional axial load; NUP type can bear bidirectional axial load. If a larger axial load is required, other types of bearings (such as deep groove ball bearings or angular contact ball bearings) must be used simultaneously to bear it.

6. What is the limit speed of cylindrical roller bearings?

The limit speed depends on the model and lubrication method. For example, for NU206, the limit speed is about 14000 r/min with grease lubrication and about 17000 r/min with oil lubrication. NUP2224ECML has 2200 r/min with grease lubrication and 3000 r/min with oil lubrication. The limit speed is close to that of deep groove ball bearings.

7. What is the material of cylindrical roller bearings?

The standard material is GCr15 high carbon chromium bearing steel; optional materials include GCr15SiMn, GCr18Mo, G20Cr2Ni4A. The standard cage is stamped steel or Nylon 66; for heavy-duty conditions, a machined brass cage (suffix M/M1) can be selected; for high-speed types, a PEEK cage can be chosen.

8. What are the accuracy grades of cylindrical roller bearings?

The standard is P0 (ordinary series); optional grades are P6, P5, P4, P2. For precision machine tools and high-speed motors, P6/P5/P4 is recommended; for ordinary machinery, P0 is sufficient.

9. How to select the clearance for cylindrical roller bearings?

For standard conditions, select CN (ordinary series); for high temperature or interference fit conditions, select C3 (larger than standard clearance); for heavy load impact conditions, select C4 (larger than C3). The clearance codes comply with ISO 5753 standard and are only applicable to bearings that are not installed and under no measuring load.

10. Can cylindrical roller bearings be used in motors?

Yes, it is the core bearing type for medium and large motors. The motor drive end usually uses NJ or NUP type (locating end), and the non-drive end uses NU or N type (free end) to compensate for axial displacement caused by thermal expansion.

11. Can cylindrical roller bearings be used on gear reducers?

Yes, cylindrical roller bearings are widely used on the input and output shafts of gear reducers. Normally an NJ/NUP (locating end) + NU (free end) combination is used to bear radial load and compensate for axial displacement.

12. Can cylindrical roller bearings be used in mining machinery?

Yes, cylindrical roller bearings are widely used in mining crushers, vibrating screens, hoists, and other equipment, providing reliable support under heavy radial and impact loads. For heavy-duty conditions, it is recommended to select the NU300/NU2200 series with a brass cage.

13. What is the allowable tilt angle for cylindrical roller bearings?

Cylindrical roller bearings allow very small misalignment between the inner and outer rings (2°–4′), which requires high precision in shaft and housing bore machining. If a larger angular error needs compensation, it is recommended to use spherical roller bearings.

14. How should the fit for cylindrical roller bearing installation be selected?

The inner ring and shaft usually adopt an interference fit, while the outer ring and housing bore usually adopt a clearance fit. For light load inner ring rotation, select k6 for the shaft and H7 for the housing; for normal load, select m5/m6 for the shaft; for heavy or impact load, select n6/p6 for the shaft and K7 for the housing. For NU/N type free end bearings, either the inner or outer ring must accommodate changes in the shaft and housing length.

15. What should be noted when installing cylindrical roller bearings?

They have a separable structure; the inner and outer rings can be installed separately. Keep the installation environment clean; use special tools, and never directly hit the bearing. For NU/N type free end bearings, either the inner or outer ring must allow axial movement; for NJ/NUP type locating ends, axial fixation should be considered. After installation, check if the rotation is smooth without jamming or abnormal noise.

16. What is the difference between cylindrical roller bearings and deep groove ball bearings?

Deep groove ball bearings have point contact, mainly bear radial loads and certain bidirectional axial loads, have the highest limiting speed, and the lowest friction torque, suitable for light-load high-speed general scenarios; cylindrical roller bearings have line contact, radial load capacity is 2–3 times higher than deep groove ball bearings of the same size, limiting speed is close to deep groove ball bearings, mainly bear radial loads, suitable for heavy-load radial conditions.

17. What is the difference between cylindrical roller bearings and tapered roller bearings?

Tapered roller bearings can bear relatively heavy combined radial and axial loads; the larger the contact angle, the higher the axial load capacity, but the limiting speed is relatively low and usually requires paired installation; cylindrical roller bearings mainly bear radial loads, have high radial load capacity, higher limiting speed, the NU/N type cannot bear axial loads, while the NJ/NUP type can bear unidirectional/bidirectional axial loads.

18. Can cylindrical roller bearings be customized?

Materials (GCr15SiMn/GCr18Mo/G20Cr2Ni4A/Stainless Steel/Ceramic), cages (Brass/Nylon/PEEK), accuracy grades (P6/P5/P4/P2), clearance (C2/C3/C4/C5), sealing forms (ZZ/2RS/Open), special grease (High Temperature/Extreme Pressure), etc., can be customized.

19. How is the lifespan of a cylindrical roller bearing calculated?

Bearing life is usually expressed by basic rated life L10, calculated by the formula L10=(C/P)^(10/3)×10^6/60n, where C is the rated dynamic load, P is the equivalent dynamic load, and n is the speed. The life exponent for cylindrical roller bearings is 10/3 (for ball bearings it is 3).

20. Do cylindrical roller bearings comply with RoHS and REACH?

Standard cylindrical roller bearings comply with RoHS (2011/65/EU) and REACH regulations, and do not contain SVHC (Substances of Very High Concern).

Technical FAQ

What is the difference between NU and NJ?

NU generally allows axial displacement, while NJ can locate the shaft in one direction. Confirm the full arrangement with the opposite bearing.

Can cylindrical roller bearings carry axial load?

Only certain flange arrangements can carry meaningful axial load. Do not assume every cylindrical bearing is suitable for thrust.

Authoritative references

For dimensional and quality references, see ISO standards and confirm the exact edition required for your market with the engineering team.

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