71904 ACD/P4ADBC
71900 Series Super Precision Angular Contact Ball Bearings
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Part No.
Part No.
71904 ACD/P4ADBC
Basic Information
System of measurement
Metric
Weight
0.07 kg
Tolerance class
P4A
Seal type
Open
For load direction
Angular Contact
Main Dimensions
Bore diameter
20 mm
Bore diameter tolerance
-0.004mm to 0
Outside diameter
37 mm
Outside diameter tolerance
-0.004mm to 0
Width
18 mm
Width tolerance
-0.2mm to 0
Contact angle
25 °
Ball & Washer Dimensions
Ball diameter
4.762 mm
Ball quantity
15
Performance
Temperature range
- 30°C to 110 °C
Radial dynamic load rating
2106 lbf
Radial static load rating
1372 lbf
Limiting speed
100.5 X 1000 rpm
Lubrication
Lubricated
Matched arrangement
Duplex Back-to-Back (DB)
Number of bearings in matched set
2
Universal matching bearing
No (Standard)
Preload
Moderate / Class C
Materials
Ring material
Chrome Steel
Ball material
Chrome Steel
Cage material
Phenolic
Technical Drawings
No drawings available at the moment, will be launched soon
In Stock
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71904 ACD/P4ADBC Bearing Product Overview & Core Advantages
The 71904 ACD/P4ADBC is a precision angular contact ball bearing designed for demanding applications requiring exceptional rotational accuracy and rigidity. This duplex back-to-back (DB) arrangement comes pre-matched and preloaded (Moderate / Class C), delivering superior performance in handling combined loads—simultaneously managing radial forces and thrust loads in both directions. Manufactured to P4A tolerance class, it ensures minimal runout and vibration, making it ideal for high-speed spindles and other high-precision machinery. Its compact design, with a 20 mm bore and 37 mm outside diameter, offers a space-saving solution without compromising on performance or load capacity.
71904 ACD/P4ADBC Bearing Model Code Explained, Specifications & Naming Convention
| Code Segment | Technical Meaning |
| 71904 | Basic bearing series, indicating a light series angular contact bearing with 20mm bore, 37mm OD. |
| AC | Angular Contact design with a 25° contact angle. |
| D | Duplex Back-to-Back (DB) arrangement. Two bearings are mounted together with their back faces contacting. |
| P4A | High Precision Tolerance Class, providing extremely tight dimensional and running accuracy. |
| DBC | Suffix indicating a specific preload level (Moderate / Class C) applied to the duplex set. |
71904 ACD/P4ADBC Bearing Structural Features & Performance Benefits
- High Rigidity & Stability: The duplex back-to-back (DB) configuration creates a wide, rigid support system that effectively resists moment loads and shaft deflection, ensuring exceptional operational stability.
- Superior Load Capacity: With a 25° contact angle and a dynamic load rating of 2106 lbf, this bearing is engineered to handle significant combined radial and axial loads from both directions simultaneously.
- Optimized High-Speed Performance: The lightweight phenolic resin cage minimizes centrifugal forces, while the precision-ground chrome steel components and optimized internal geometry contribute to a high limiting speed of 100,500 rpm.
- Pre-Configured for Precision: The factory-applied moderate preload (Class C) eliminates internal clearance, reducing axial and radial play for immediate high-accuracy performance upon installation, which is critical for machine tool spindles.
- Pre-Lubricated for Immediate Service: The bearing is supplied lubricated, ready for immediate installation and initial operation within its specified temperature range of -30°C to 110°C.
71904 ACD/P4ADBC Bearing Typical Application Areas
This precision duplex bearing set is specifically engineered for high-performance applications where accuracy, speed, and rigidity are paramount. Key industries and equipment include:
- Machine Tool Spindles: High-speed milling, grinding, and turning centers.
- Precision Rotary Systems: Industrial robots, CNC rotary tables, and indexing heads.
- High-Frequency Motors & Spindles: PCB drilling spindles and small high-speed electric motors.
- Medical & Laboratory Equipment: Centrifuges and precision analytical instruments.
- Aerospace & Defense Systems: Gyroscopes, radar platforms, and other critical guidance mechanisms.
