71911 ACD/P4AQBCB
71900 Series Super Precision Angular Contact Ball Bearings
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Part No.
Part No.
71911 ACD/P4AQBCB
Basic Information
System of measurement
Metric
Weight
0.72 kg
Tolerance class
P4A
Seal type
Open
For load direction
Angular Contact
Main Dimensions
Bore diameter
55 mm
Bore diameter tolerance
-0.004mm to 0
Outside diameter
80 mm
Outside diameter tolerance
-0.004mm to 0
Width
52 mm
Width tolerance
-0.2mm to 0
Contact angle
25 °
Ball & Washer Dimensions
Ball diameter
7.938 mm
Ball quantity
23
Performance
Temperature range
- 30°C to 110 °C
Radial dynamic load rating
10980 lbf
Radial static load rating
12375 lbf
Limiting speed
34 X 1000 rpm
Lubrication
Lubricated
Matched arrangement
Quadruplex Back-to-Back (QBC)
Number of bearings in matched set
4
Universal matching bearing
No (Standard)
Preload
Light / Class B
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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71911 ACD/P4AQBCB Bearing Product Overview & Core Advantages
The 71911 ACD/P4AQBCB is a super-precision angular contact ball bearing designed for the most demanding applications. Its defining feature is its quadruplex back-to-back (QBC) matched arrangement, delivering exceptional system rigidity and stability under complex loading conditions. Manufactured to a P4A tolerance class, this bearing offers extremely high running accuracy, making it ideal for high-speed spindles and other precision machinery where minimal runout and vibration are critical. The combination of a 25° contact angle and a light preload (Class B) ensures optimal performance for handling combined radial and axial loads simultaneously.
71911 ACD/P4AQBCB Bearing Model Code Explained, Specifications & Naming Convention
| Code Segment | Technical Meaning |
|---|---|
| 71911 | Basic bearing series and size designation (55mm bore, 80mm OD, 52mm width). |
| ACD | Angular Contact design with a 25° contact angle. |
| P4A | Indicates a high-precision tolerance class (superior to ABEC 7/P4), ensuring extremely tight dimensional and running accuracy. |
| QBC | Signifies the bearing is supplied as a Quadruplex Back-to-Back matched set. This arrangement provides maximum rigidity against moment loads. |
| B | Denotes a Light Preload applied to the bearing set, which eliminates internal clearance for precise shaft positioning and improved system stiffness. |
71911 ACD/P4AQBCB Bearing Structural Features & Performance Benefits
- Unmatched Rigidity and Stability: The quadruplex back-to-back (QBC) arrangement of four bearings creates an extremely rigid support system. This configuration is highly effective at resisting moment loads and tilting, which is crucial for maintaining precision in machine tool spindles.
- High-Speed Capability: The use of a lightweight, durable phenolic resin cage reduces centrifugal forces, allowing for a high limiting speed of 34,000 rpm. The open design and factory-applied lubrication facilitate efficient heat dissipation.
- Superior Load Capacity: With a 25° contact angle, this bearing is optimized to handle significant combined radial and axial loads. The dynamic and static load ratings (10,980 lbf and 12,375 lbf respectively) ensure long service life under demanding conditions.
- Precision Engineering: The P4A tolerance class guarantees minimal dimensional variation and extremely low running vibration, which is essential for achieving high surface finishes and positional accuracy in precision applications.
71911 ACD/P4AQBCB Bearing Typical Application Areas
This high-precision bearing is specifically engineered for advanced machinery requiring the highest levels of accuracy, speed, and rigidity. Key application areas include:
- High-Speed Machine Tool Spindles (e.g., for milling, grinding, and drilling)
- Precision Grinding Spindles
- High-Frequency Machining Centers
- Advanced Robotic Drives and Servo Motors
- Aerospace and Defense Positioning Systems
