Overview
The Timken Fafnir RCJ1 5/8 is an industrial-duty flange-mount ball bearing unit designed for standard applications requiring reliable shaft support. This unit features a wide-inner-ring ball bearing housed in a durable cast iron flanged cartridge with four bolt holes for direct mounting onto machinery. The RCJ series combines proven bearing design with field-proven construction, making it suitable for general-purpose industrial automation and power transmission systems.
Key Features
- Four-Bolt Flange Mounting: Direct installation on flat surfaces with 4.125″ bolt center-to-center length and 5.844″ bolt circle diameter.
- Wide-Inner-Ring Bearing: Provides additional shaft support and accommodates relubrication without removal.
- Eccentric Locking Collar: Self-locking design secured with setscrew for slip-fit mounting on straight shafts.
- Cast Iron Housing: Robust, corrosion-resistant construction suitable for wet and contaminated environments.
- Factory Prelubricated: Comes assembled with grease and stainless steel grease fitting for scheduled maintenance.
- Contact Seal Design: Double rubber seals protect the bearing from contaminants and moisture.
Technical Specifications
- Bore Diameter (Shaft Size): 1-5/8 inches
- Mounting Style: Four-Bolt Flange Mount
- Bolt Center-to-Center Length: 4.125 inches
- Bolt Circle Diameter: 5.844 inches
- Overall Length/Diameter: 5.375 inches
- Overall Depth: 2.334 inches
- Housing Material: Cast Iron
- Bearing Type: Single-Row Ball Bearing with Wide Inner Ring
- Locking Device: Eccentric Collar with Setscrew
- Seal Type: Double Rubber Contact Seal
- Lubrication: Factory Prelubricated, Relubricatable with Grease Fitting
- Radial Dynamic Load Capacity: 36,300 lbf
- Radial Static Load Capacity: 4,600 lbf
- Maximum Speed: 3,230 rpm
- Operating Temperature Range: -30°F to 275°F (-22°C to 135°C)
- Duty Type: Standard Industrial Duty
Typical Applications
The RCJ1 5/8 is widely used in industrial machinery including conveyor systems, electric motors, agricultural equipment, mining machinery, logging equipment, and food processing systems. Its robust cast iron housing and sealed bearing design make it ideal for applications exposed to moisture, dust, and other environmental contaminants. The slip-fit mounting accommodates retrofit installations on existing equipment.
Compatibility & Replacements
Compatible With
- Industrial shaft alignment up to 1-5/8″ diameter
- Standard four-bolt flange mounting patterns
- Grease-based lubrication systems
- General industrial machinery and equipment
Replaces / Drop-In Replacement For
The Timken Fafnir RCJ1 5/8 is a direct replacement for original Fafnir RCJ1 5/8 units. When replacing mounted bearing units, verify mounting dimensions and load requirements with your equipment manufacturer or system integrator before ordering.
Works With
- Cast iron pillow block and flange mount housings
- Timken and Fafnir bearing lubrication products
- Standard industrial maintenance and relubricatable bearing protocols
- Shaft sleeve and adapter systems for slip-fit applications


















