STANDARD REFERENCE / YZEFY SPROCKETS
BS sprockets
BS sprockets are used with British Standard and related B-series roller chains identified by references such as 06B, 08B, 10B and 12B. They serve UK and European equipment, industrial drives, conveyors, material handling, packaging and MRO replacement work. A BS chain number is only the starting point. The finished sprocket also depends on simplex, duplex or triplex construction, number of teeth, bore, keyway and hub. For a standard, custom or replacement part, send the BS drawing, chain marking, old sprocket, sample or measured dimensions with the quantity and application.
Standard reference
BS Sprockets
- SpecificationDetails
- Standard referencesBS ISO 606:2015 for the current UK implementation, with BS 228 retained as a legacy drawing reference
- Common B-series references04B, 05B, 06B, 08B, 10B, 12B, 16B, 20B and 24B
Quick Specifications
| Specification | Details |
|---|---|
| Standard references | BS ISO 606:2015 for the current UK implementation, with BS 228 retained as a legacy drawing reference |
| Common B-series references | 04B, 05B, 06B, 08B, 10B, 12B, 16B, 20B and 24B |
| Reference pitch range | 6.000 mm to 38.100 mm in the table below |
| Strand | Simplex, duplex and triplex, stated with the complete chain suffix |
| Sprocket forms | Type A plate, Type B hub, Type C double hub and drawing-defined forms |
| Bore options | Pilot bore, finished bore, keyed bore, bushing interface and custom shaft interface |
| Selection basis | B-series dimensions, teeth, strand spacing, bore, keyway, hub and drawing revision |
| Custom and replacement | BS drawing, BS 228 reference, chain marking, sample, photo or measured sprocket |
Available Sizes
BS, DIN and ISO pages use one shared B-series child page for each canonical chain size.
Chain & Size Reference
The following common B-series chain dimensions are in millimetres. They provide a first check for the mating chain. They are not a complete sprocket size table. Sprocket pitch diameter, outside diameter, tooth width and bore depend on the number of teeth and the selected form.
| Chain reference | Pitch | Roller diameter | Inner width |
|---|---|---|---|
| 04B | 6.000 | 4.000 | 2.800 |
| 05B | 8.000 | 5.000 | 3.000 |
| 06B | 9.525 | 6.350 | 5.720 |
| 08B | 12.700 | 8.510 | 7.750 |
| 10B | 15.875 | 10.160 | 9.650 |
| 12B | 19.050 | 12.070 | 11.680 |
| 16B | 25.400 | 15.880 | 17.020 |
| 20B | 31.750 | 19.050 | 19.560 |
| 24B | 38.100 | 25.400 | 25.400 |
Add the strand suffix to the chain reference. The transverse spacing and total tooth width for 08B-2 or 08B-3 are different from 08B-1, so the sprocket cannot be selected from the base number alone.
Available Sprocket Configurations
Sprocket forms
- Type A plate sprockets for hubless or separately mounted assemblies.
- Type B sprockets with a hub on one side.
- Type C sprockets with hubs on both sides or a wider shaft interface.
- Idler, split, weld-on, bushing-mounted and other drawing-defined forms.
Strand configurations
Simplex, duplex and triplex forms are selected from the chain row count and transverse spacing. State the complete reference, such as 08B-1, 08B-2 or 08B-3, together with the tooth count and mounting dimensions.
Materials
Carbon steel is common for general BS transmission and conveyor drives. Alloy steel can be selected for higher load, shock or wear requirements. Stainless steel suits corrosion, washdown and cleaning exposure. Cast iron, aluminum and engineering plastics may be considered for specific low-load or weight-sensitive applications.
State the material grade, supply condition and certificate requirement in the RFQ. The correct material depends on load, speed, shock, lubrication, corrosion, temperature and cleaning conditions, not on the BS label alone.
Heat Treatment & Surface Treatment
Tooth hardening and induction hardening can address repeated tooth wear. Carburizing may be specified when a hard case and tougher core are required. Protective surface treatments can be considered for corrosion exposure, storage or washdown service.
Include hardness, case depth, treated area, surface finish and inspection method when the drawing controls them. If a legacy BS drawing lacks treatment information, send the load cycle, speed, lubrication and environment with the replacement details.
Custom BS Sprockets
Custom BS sprockets are defined by the exact chain reference and machine interface. Send the BS or BS ISO reference, chain size, number of teeth, strand, bore, keyway, hub dimensions and quantity. Include material, treatment, tolerances, marking and inspection requirements from the drawing.
For a repeat OEM order, include the drawing revision and mating chain reference. For a sample-based order, add photos, tooth count, pitch, roller diameter, inner width, face width and shaft measurements. Application speed, load and center distance can help resolve missing dimensions.
Replacement BS Sprockets
Replacement BS sprockets are used for old British machinery, UK and European equipment, legacy BS 228 drawings and MRO work on B-series chain drives. Provide the original drawing, BS or BS ISO reference, chain marking, tooth count, bore, keyway, hub, face width, photos and sample details when available.
BS 228 can remain on an old drawing even when the current project uses BS ISO 606. Keep the legacy reference in the RFQ and compare the chain dimensions, tooth form, strand spacing and shaft interface before selecting a current replacement. Worn tooth tips should not be copied as the design profile.
Applications
BS sprocket inquiries commonly arise from UK and European equipment, legacy British machinery, material handling, conveyors, packaging, processing, agriculture, woodworking and MRO replacement programs. The BS reference can identify the likely B-series family, while the original drawing and chain marking establish the actual part.
The application and country of origin do not determine the tooth count or shaft connection. Confirm the chain dimensions, teeth, strand spacing, bore, keyway and hub before ordering.
Standard & Compatibility Notes
BS 228:1994 is a legacy British Standard record for short-pitch transmission precision roller chains and chain wheels. BSI records that edition as withdrawn and identifies it as identical to ISO 606:1994. Current UK projects may use BS ISO 606:2015, the UK implementation of the ISO system.
The historical relationship is useful for interpreting old drawings, but it is not a blanket interchangeability statement. Check the edition, complete chain designation, series, tooth form, strand spacing and shaft interface. A B-series pitch match alone does not approve a replacement.
How to Select
- Copy the exact BS, BS ISO or BS 228 reference from the drawing.
- Record the complete B-series chain number and simplex, duplex or triplex suffix.
- Confirm pitch, roller diameter, inner width and transverse spacing.
- Record driver and driven teeth, speed ratio, center distance, wrap and chain line.
- Select Type A, Type B, Type C or another drawing-defined form.
- Specify bore, keyway, bushing, hub, material, treatment and inspection.
- Send the original drawing or a measured sample for legacy replacement work.
FAQ
What are BS sprockets?
BS sprockets are used with British Standard and related B-series roller chains. The exact BS or BS ISO reference, chain size, strand and shaft interface are needed for selection.
What is BS 228?
BS 228:1994 is a legacy British Standard reference for short-pitch transmission precision roller chains and chain wheels. It is recorded as withdrawn, so the drawing edition should be retained when a replacement is requested.
What does B-series mean?
B-series identifies the European family of chain dimensions used in many BS, DIN and ISO references. The full chain number and strand suffix still determine the chain dimensions required by the sprocket.
What is the relationship between BS 228 and ISO 606?
BSI records BS 228:1994 as identical to ISO 606:1994, while current UK work may use BS ISO 606:2015. The document edition and actual dimensions still need checking for a replacement.
Are BS and ISO sprockets interchangeable?
Current BS ISO 606 and ISO 606 references are closely related, but a legacy BS drawing or a different chain series can change the fit. Compare chain dimensions, tooth form, strand spacing and mounting details.
Can old BS sprockets be reproduced?
Yes. Send the BS reference, old drawing, chain marking, tooth count, bore, keyway, hub and sample or measured dimensions. The mating chain should be checked before the worn part is reproduced.
Request a Quote for BS Sprockets
Send the BS or BS ISO reference, chain designation, strand count, number of teeth, bore, keyway, hub, quantity and application. For an old British machine, attach the BS 228 drawing, chain marking, photos, sample details and shaft measurements. This supports a standard, custom or replacement sprocket review.