50B18 18-Tooth Sprocket for #50 Chain – 1" Bore, 1/4" Keyway

The 50B18 18-Tooth Sprocket is a heavy-duty chain-drive sprocket designed for use with #50 roller chain in compatible commercial garage door operators, jackshaft systems, industrial door equipment, and other chain-driven mechanical assemblies.

This sprocket features 18 teeth, a 1-inch finished bore, and a 1/4-inch keyway for positive engagement with a keyed shaft. The keyed bore helps transfer torque between the shaft and sprocket while reducing the possibility of the sprocket slipping under load.

SSC supplies this sprocket with set screws included, allowing it to be secured to a compatible keyed shaft during installation.

Features

• 18-tooth sprocket

• Designed for #50 roller chain

• 1" finished bore

• 1/4" keyway

• Set screws included

• Designed for keyed-shaft installation

• Suitable for chain-driven commercial garage door equipment

• Useful for replacement of worn or damaged drive sprockets

• Compatible with properly sized #50 chain systems

• Durable mechanical drive component for professional service and repair applications

#50 Roller Chain Compatibility

This sprocket is specifically designed for:

#50 Roller Chain

#50 chain has a nominal pitch of 5/8", so the sprocket tooth profile must match this chain size for correct engagement and reliable operation.

Do not substitute a sprocket intended for #41, #40, #65, or another chain size.

SSC separately lists sprockets for multiple chain sizes, making correct chain identification important before ordering.

18-Tooth Configuration

The sprocket uses:

18 Teeth

Tooth count is important because it affects the relationship between shaft speed, chain speed, and driven-component speed.

When replacing an existing sprocket, use the same tooth count unless the drive system has been intentionally engineered for a different ratio.

Changing sprocket tooth count can alter:

• Door or operator speed

• Torque multiplication

• Chain travel speed

• Drive-system loading

• Overall mechanical ratio

For direct replacement, match the original 18-tooth configuration.

1" Finished Bore

The sprocket has a:

1" Bore

This finished bore is designed to mount on a compatible 1-inch shaft.

Before ordering, measure the shaft diameter carefully. A sprocket with the wrong bore size will not properly fit the shaft and should not be forced into place.

1/4" Keyway

The bore includes a:

1/4" Keyway

The keyway accepts a compatible shaft key that mechanically locks the sprocket's rotation to the shaft.

This arrangement allows torque to be transmitted through the shaft and sprocket without relying solely on set-screw pressure.

A properly installed key is especially important in powered chain-drive applications where the sprocket may experience repeated starting, stopping, and reversing loads.

Set Screws Included

SSC specifies that its sprockets include:

Set Screws

The set screws provide additional retention on the shaft after the sprocket and shaft key are positioned correctly.

During installation, verify that:

• The shaft key is properly seated

• The sprocket is aligned with the chain path

• Set screws are properly tightened

• The sprocket does not wobble or move axially

• Chain alignment remains straight

Common Applications

The 50B18 sprocket may be used in compatible:

• Commercial garage door operators

• Jackshaft drive assemblies

• Chain-driven overhead door systems

• Industrial door equipment

• Shaft-driven mechanical assemblies

• Replacement operator drive systems

• General #50 roller-chain applications

Compatibility depends on the original equipment configuration, shaft diameter, chain size, and required tooth count.

Replacement Applications

A sprocket may require replacement if you notice:

• Worn or hooked teeth

• Excessive chain noise

• Uneven chain engagement

• Damaged keyway

• Loose fit on the shaft

• Cracked or damaged sprocket hub

• Excessive chain jumping

• Abnormal drive vibration

Whenever replacing a worn sprocket, also inspect the roller chain and other sprockets in the drive system.

A badly worn chain can quickly damage a new sprocket.

Specifications

• SSC Part Number: 50B18

• Product Type: Roller Chain Sprocket

• Chain Size: #50

• Chain Pitch: 5/8"

• Tooth Count: 18

• Bore Diameter: 1"

• Keyway: 1/4"

• Set Screws: Included

• Mounting Type: Keyed Shaft

• Operation: Mechanical Chain Drive

• Quantity: 1 Sprocket

Package Contents

• 1 × 50B18 18-Tooth Sprocket

• Set Screw(s)

50B18 vs. Other #50 Chain Sprockets

SSC offers several sprocket sizes for #50 chain, including:

• 50B12 – 12 Tooth, 1" Bore

• 50B18 – 18 Tooth, 1" Bore

• 50B24 – 24 Tooth, 1" Bore

• 50B30 – 30 Tooth, 1" Bore

• 50B40 – 40 Tooth, 1" Bore

All of these listed #50-chain sprockets use a 1" bore with a 1/4" keyway, but the tooth count changes the drive ratio.

Always replace the original sprocket with the correct tooth count unless the equipment manufacturer specifies otherwise.

Before Ordering

Confirm all of the following:

• Chain is #50 roller chain

• Existing sprocket has 18 teeth

• Shaft diameter is 1"

• Shaft uses a 1/4" keyway

• Overall sprocket configuration matches the equipment

• There is sufficient clearance for the replacement sprocket

Do not order based only on bore diameter or tooth count. Chain size must also match.

Installation Notes

Before installation:

• Disconnect electrical power to powered equipment

• Secure the door and drive system against movement

• Inspect the shaft and keyway

• Inspect the chain for wear or damage

• Position the sprocket in alignment with the mating sprocket

• Install the correct shaft key

• Tighten the supplied set screws securely

• Adjust chain tension according to the equipment manufacturer's requirements

Poor sprocket alignment can cause excessive chain wear, noise, vibration, and premature component failure.

Safety

Always disconnect and lock out power before servicing chain-driven garage door operators or industrial equipment.

Never work on sprockets, chains, shafts, or drive assemblies while the system can move unexpectedly.

Commercial garage door systems may contain heavy doors, counterbalance springs, chains, and rotating components capable of causing serious injury. Service should be performed by individuals familiar with the equipment and proper safety procedures.