50B12 12-Tooth #50 Roller Chain Sprocket – 1" Bore, 1/4" Keyway

The 50B12 is a 12-tooth roller chain sprocket designed for ANSI #50 single-strand roller chain and compatible 1" keyed shafts.

Its finished 1" bore and 1/4" keyway provide a secure mechanical connection between the sprocket and shaft, making it suitable for commercial garage door operators, chain-drive assemblies, gate operators, and other mechanical drive systems using #50 roller chain.

The keyway is timed with the centerline of a sprocket tooth for consistent shaft and sprocket orientation.

Product Features

• 12-tooth drive sprocket

• Designed for ANSI #50 roller chain

• 1" finished bore

• 1/4" keyway

• Keyway timed with centerline of tooth

• Designed for keyed shaft installation

• Compact 12-tooth configuration

• Suitable for commercial operator and mechanical drive applications

• Replacement sprocket for compatible chain-drive assemblies

Specifications

• Model / SKU: 50B12

• Product Type: Roller Chain Sprocket

• Number of Teeth: 12

• Chain Size: ANSI #50

• Chain Pitch: 5/8"

• Bore: 1"

• Bore Type: Finished / Keyed

• Keyway: 1/4" × 1/8"

• Sprocket Style: Type B

• Pitch Diameter: Approximately 2.415"

• Outside Diameter: Approximately 2.71"

• Number of Strands: Single

Common Applications

Suitable for compatible:

• Commercial garage door operators

• Industrial overhead door operators

• Gate operators

• Chain-drive assemblies

• Jackshaft drive systems

• Mechanical power-transmission equipment

• Replacement operator sprocket applications

Compatibility

Before ordering, verify all three critical dimensions:

• Chain: #50 roller chain

• Shaft Diameter: 1"

• Keyway: 1/4"

Do not select a sprocket based only on tooth count. A 12-tooth sprocket designed for another chain size or shaft diameter will not be a direct replacement.

12-Tooth Configuration

A smaller drive sprocket such as a 12-tooth configuration may be used as part of a chain-reduction or operator drive system.

Changing sprocket tooth count can alter the drive ratio, shaft speed, and transmitted torque. When replacing an existing sprocket, match the original tooth count unless the system has been specifically engineered for a different ratio.

Package Contents

• 1 – 50B12 12-Tooth Sprocket

Roller chain, shaft, key stock, bearings, operator, and other drive components are sold separately.

Important Installation Note

Confirm chain size, shaft diameter, keyway dimensions, tooth count, and required drive ratio before installation.

Disconnect power and secure the door or driven equipment before servicing any operator or chain-drive assembly.