71904 ACD/P4ATBTC
71900 Series Super Precision Angular Contact Ball Bearings
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Part No.
Part No.
71904 ACD/P4ATBTC
Basic Information
System of measurement
Metric
Weight
0.11 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
27 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
2790 lbf
Radial static load rating
2059 lbf
Limiting speed
100.5 X 1000 rpm
Lubrication
Lubricated
Matched arrangement
Triplex Back-to-Back (TBT)
Number of bearings in matched set
3
Universal matching bearing
No (Standard)
Preload
Moderate / Class C
Materials
Ring material
Chrome Steel
Ball material
Chrome Steel
Cage material
Phenolic
Technical Drawings
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In Stock
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71904 ACD/P4ATBTC Bearing Product Overview & Core Advantages
The **71904 ACD/P4ATBTC** is a **precision angular contact ball bearing** configured in a **triplex back-to-back (TBT) matched set**. This advanced arrangement is engineered to deliver exceptional **system rigidity** and stability, making it ideal for applications requiring the highest levels of **running accuracy**. The set is pre-lubricated and features a **Moderate (Class C) preload**, ensuring optimal performance from installation without the need for initial adjustment. Its design is optimized to handle **combined loads**—significant radial and thrust loads simultaneously—with high reliability.
71904 ACD/P4ATBTC Bearing Model Code Explained, Specifications & Naming Convention
| Code Segment | Technical Meaning |
|---|---|
| 71904 | Basic bearing series, indicating a light series metric angular contact bearing with a 20mm bore. |
| ACD | **A**ngular **C**ontact bearing with a **25°** contact angle and a **D**uplex (two-bearing) design concept, here supplied as part of a triplex set. |
| P4A | Indicates a **high-precision tolerance class** (superior to ABEC 7/P4), defining extremely tight limits on bore, outside diameter, and width runout for superior **rotational accuracy**. |
| TBT | **T**riplex **B**ack-to-**B**ack arrangement. Three bearings are matched and mounted in a back-to-back configuration to maximize **moment rigidity** and system stability. |
71904 ACD/P4ATBTC Bearing Structural Features & Performance Benefits
- Superior Rigidity and Stability: The triplex back-to-back (TBT) configuration creates a statically determinate bearing system that provides extremely high resistance to moment loads and shaft deflection, which is critical for maintaining precision under heavy combined loads.
- High-Precision Performance: Manufactured to a P4A tolerance class, this bearing set guarantees minimal runout and vibration, enabling smooth operation essential for high-speed applications up to 100,500 rpm.
- Optimized for Speed and Load: The 25° contact angle offers an excellent balance between radial and axial load capacity. The phenolic cage is lightweight and robust, contributing to lower friction and higher limiting speeds.
- Ready-to-Install Solution: The set comes pre-lubricated and with a moderate preload (Class C) applied, simplifying installation and ensuring immediate, optimal performance without complex setup procedures.
71904 ACD/P4ATBTC Bearing Typical Application Areas
This precision-matched bearing set is designed for the most demanding applications, including:
- High-Frequency Machine Tool Spindles
- Precision Grinding Spindles
- High-Speed Robotic Drives
- Aerospace Control Systems
- Medical and Dental Drill Handpieces
