QJ300 Series

The QJ300 Series Double Row Angular Contact Ball Bearings are precision-engineered rotating components designed to accommodate simultaneous radial and axial loads in both directions. Structurally, this series corresponds to two single-row angular contact ball bearings arranged in a back-to-back configuration, integrated into a compact single-unit design. The internal geometry features a specific contact angle that facilitates high axial stiffness and the ability to manage tilting moments. Manufactured from vacuum-degassed chrome steel (GCr15), these bearings undergo standardized heat treatment processes to ensure dimensional stability and fatigue resistance. The QJ300 series is characterized by its reduced axial space requirement compared to paired single-row units, making it an essential component for industrial drivetrain optimization and high-speed mechanical assemblies requiring rigid shaft support.

Send inquiry

Technical Specifications and Engineering Overview: QJ300 Series Double Row Angular Contact Ball Bearings

Core Technical Advantages

Bidirectional Axial Support: The double-row configuration enables the bearing to manage thrust loads from both directions without additional components.
Space Efficiency: The integrated design offers a narrower width than two single-row bearings, allowing for compact housing designs.
High Load Density: Optimized raceway curvatures and ball complements maximize dynamic load ratings within a standard ISO 300-series footprint.
Operational Rigidity: Minimal internal clearance and high contact angles enhance the overall stiffness of the shaft system.

Key Product Characteristics

Parameter Category	Technical Specification
Material	High-Carbon Chromium Bearing Steel (GCr15/SAE 52100)
Contact Angle	Standard 30° / 40° Options
Precision Class	P6 (ABEC-3) / P5 (ABEC-5)
Cage Material	Pressed Steel / Machined Brass / Nylon (PA66)
Lubrication Type	Open / Z (Shielded) / RS (Sealed)
Internal Clearance	C2 / C0 (Normal) / C3

Primary Application Scenarios

Industrial Pumps & Compressors: Managing axial thrust and radial shaft deflection in fluid handling equipment.
Agricultural Machinery: Support for wheel hubs and power take-off (PTO) units exposed to multidirectional stress.
Transmission Systems: Integration into gearboxes and reducers where precise shaft positioning is required under load.
Textile & Printing Equipment: Ensuring synchronized movement in high-speed rollers requiring low vibration levels.

Handling and Maintenance Protocols

Storage Conditions

Bearings must be stored in their original anti-rust packaging in a dry, temperature-controlled environment with relative humidity not exceeding 60%. Avoid direct contact with floors or walls to prevent moisture condensation. For sealed bearings, verify the manufacture date to ensure grease stability within its shelf life.

Installation and Usage Notes

Force Application: During mounting, apply pressure only to the ring being fitted (inner ring for shaft fits, outer ring for housing fits) to avoid "brinelling" or raceway damage.
Cleanliness: Maintain a contaminant-free workspace; microscopic particles can lead to premature surface fatigue and spalling.
Alignment: Precise concentricity between shaft and housing is mandatory, as angular contact bearings are sensitive to severe misalignment which causes uneven load distribution.
Lubrication Management: For open-type bearings, ensure the lubricant is compatible with the operating temperature and rotational velocity of the specific application.

Designation	Principal dimensions(mm)				Basic load ratings(KN)		Basic load ratings(kgf)		Limiting Speed (rpm)		Distance of action point	Installation dimensions(mm)			Weight
Designation	d	D	B	r(min)	Cr	Cor	Cr	Cor	Grease	Oil	a0(mm)	da(min)	Da(max)	ra(max)	(kg)
QJ306	30	72	19	1.1	46000	63000	4700	6450	8000	11000	35.7	37	65	1	0.42
QJ307	35	80	21	1.5	55000	80000	5600	8150	7100	9500	40.3	44	71	1.5	0.57
QJ308	40	90	23	1.5	67000	100000	6850	10200	6300	8500	45.5	49	81	1.5	0.78
QJ309	45	100	25	1.5	87500	133000	8900	13500	5600	7500	50.8	54	91	1.5	1.05
QJ310	50	110	27	2	102000	159000	10400	16200	5000	6700	56	60	100	2	1.35
QJ311	55	120	29	2	118000	187000	12000	19100	4500	6300	61.3	65	110	2	1.75
QJ312	60	130	31	2.1	135000	217000	13800	22200	4300	5600	66.5	72	118	2	2.15
QJ313	65	140	33	2.1	153000	250000	15600	25500	3800	5300	71.8	77	128	2	2.7
QJ314	70	150	35	2.1	172000	285000	17500	29100	3600	5000	77	82	138	2	3.18
QJ315	75	160	37	2.1	187000	320000	19100	33000	3400	4800	82.3	87	148	2	3.9
QJ316	80	170	39	2.1	202000	360000	20600	37000	3200	4300	87.5	92	158	2	4.6
QJ317	85	180	41	3	218000	405000	22300	41000	3000	4000	92.8	99	166	2.5	5.34
QJ318	90	190	43	3	235000	450000	23900	45500	2800	3800	98	104	176	2.5	6.4
QJ319	95	200	45	3	251000	495000	25600	50500	2600	3600	103.3	109	186	2.5	7.4