A Type, B Type, and C Type Sprockets: Hub Design, Bore Specifications, and Installation Methods Explained
Company Profile
Tianjin OuNaiDa Transmissions Technology Co., Ltd. is a professional manufacturer specializing in precision motion components and power transmission solutions. With more than 20 years of manufacturing experience, we provide high-quality gears, gear racks, sprockets, roller chains, timing pulleys, timing belts, linear guides, ball screws, and customized mechanical transmission components for global customers.
Equipped with advanced CNC machining centers, gear processing equipment, precision grinding machines, and professional inspection systems, OuNaiDa focuses on stable quality, accurate manufacturing, and reliable delivery. Our engineering team supports OEM and ODM projects by producing components according to customer drawings, samples, or specific application requirements.
Our products are widely applied in industrial automation, CNC machinery, robotics, packaging equipment, manufacturing systems, and various mechanical transmission applications. We continuously improve our production technology and quality management system to meet international standards and customer expectations.
With a commitment to precision, reliability, and customer-oriented service, Tianjin OuNaiDa has established long-term partnerships with customers worldwide. We aim to become a trusted global partner for precision motion components and intelligent manufacturing solutions.
Precision Motion Components | Empowering Global Intelligent Manufacturing
The Main Difference Between A, B, and C Type Sprockets Is the Hub Structure
The primary difference between A, B, and C type sprockets is the design and position of the hub.
A Type sprockets
typically consist only of a toothed plate without a projecting hub.
B Type sprockets
have a hub on one side of the sprocket plate.
C Type sprockets
have hubs on both sides of the sprocket plate.
Sprockets
Some manufacturers also offer special designs, such as asymmetric double-hub structures or customized configurations. Therefore, sprocket selection should always be based on the manufacturer's dimensional drawing rather than appearance alone.
Where Are A Type Sprockets Used?
A Type sprockets have a relatively thin overall structure and are commonly used in applications where the sprocket is mounted to another component, such as:
Flanges
Hubs
Clutches
Special mounting plates
They can also be used as part of multi-sprocket assemblies.
Because A Type sprockets do not have an integrated hub, they are not always suitable for directly transmitting high torque through a shaft connection. The actual load capacity depends on:
Mounting structure
Bolt arrangement
Supporting components
Connection rigidity
Proper mechanical design is required to ensure reliable torque transmission.
Why Are B Type Sprockets the Most Common?
B Type sprockets feature a hub on one side, providing a longer bore engagement length between the sprocket and shaft.
Advantages include:
Easy machining of keyways
Convenient installation of set screws
Compatibility with taper bush systems
Compact overall design
Because of their balance between strength, size, and installation convenience, B Type sprockets are widely used in industrial power transmission systems.
During design, the hub orientation must be confirmed to avoid interference with:
Bearing housings
Machine frames
Adjacent components
When Should C Type Sprockets Be Selected?
C Type sprockets have hubs on both sides, providing a longer total bore length and improved shaft support.
They are suitable for applications requiring:
Longer shaft engagement
Larger hub diameter
Higher installation stability
Increased torque capacity
However, C Type sprockets require more axial installation space. Designers should consider:
Total sprocket thickness
Shaft spacing
Assembly and removal clearance
It is important to note that a double-row or multi-row sprocket is not automatically a C Type sprocket. Chain rows and hub configuration are two separate specifications.
LTB, Bore, and Keyway Dimensions Must Be Confirmed Together
LTB (Length Through Bore) refers to the total length of the sprocket bore along the shaft direction.
Typical measurement methods:
B Type sprocket: measured from the hub face to the opposite side of the sprocket plate
C Type sprocket: measured from one hub face to the other hub face
For finished bore sprockets, the following information must also be specified:
Bore diameter tolerance
Keyway width and depth
Set screw quantity and position
Hub dimensions
A sprocket with the same bore diameter may still be unsuitable if the keyway or LTB dimensions are different.
Pilot Bore, Finished Bore, and Taper Bush Sprockets
Pilot Bore Sprockets
Pilot bore sprockets are supplied with a smaller machining hole and are intended for customer-side secondary machining.
Advantages:
Flexible customization
Suitable for special shaft requirements
Finished Bore Sprockets
Finished bore sprockets are supplied ready for installation, including:
Shaft bore
Keyway
Set screw arrangement
They are commonly used for standard industrial replacement applications.
Taper Bush Sprockets
Taper bush sprockets use a standardized taper bush system for shaft connection.
Advantages include:
Easy installation and removal
Convenient maintenance
Reduced inventory complexity
However, customers must confirm:
Correct taper bush series
Shaft diameter
Installation direction
Different connection methods should not be modified without checking hub strength and torque capacity.
Recommended Information for Sprocket Enquiries
For accurate sprocket selection, please provide:
Chain type and size
Number of teeth
Number of chain rows
A, B, or C type configuration
Outside diameter
Bore diameter
Keyway dimensions
Set screw requirements
Hub diameter
LTB dimension
Material specification
Tooth surface heat treatment
Required quantity
For replacement sprockets, it is recommended to provide:
Front view photo
Side view photo
Bore and keyway photos
Photos with a caliper or scale reference
Reliable Sprocket Solutions for Industrial Power Transmission
Correct sprocket selection requires more than matching chain size and tooth number. Hub structure, bore design, shaft connection method, and installation conditions must all be considered to ensure reliable operation.
Tianjin OND Precision Motion Components provides standard sprockets, finished bore sprockets, and customized machining services according to customer drawings, samples, and application requirements.
Providing complete hub and bore information helps prevent common problems such as additional machining, incorrect fit, or installation failure after delivery.
Precision Motion Components | Empowering Global Intelligent Manufacturing
