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Pilot Bore Sprockets – 1/2” Pitch Roller Chain Sprockets

At Bolton Engineering Products Ltd, we stock a full range of pilot bore sprockets designed for reliable, efficient power transmission in machinery, conveyors, automation systems, and chain-driven equipment.

These plain bore sprockets (Type A) have an unprepared bore and require a keyway and set screw for installation, allowing them to be fully customized to fit any shaft size and meet your specific needs.

BEP Ltd have you covered – whether it be a light-duty sprocket or an item designed for continuous use, all our parts are made from high-strength materials and custom machined to tight tolerances at very competitive prices.

What Is a Pilot Bore Sprocket?

A pilot bore sprocket is a chain sprocket supplied with a basic, oversized bore, allowing engineers or machinists to finish-machine it to the exact shaft diameter or keyway required.

These sprockets are popular in:

  • Manufacturing & processing equipment
  • Agricultural and industrial machinery
  • Conveyors and material handling systems
  • Motorcycles, bicycles & chain-driven vehicles
  • General engineering and fabrication workshops

Their flexibility makes them a go-to choice for custom drive systems and OEM applications.

Technical Specifications

Specification

Details

Product Type

Pilot Bore / Plain Bore Sprocket

Chain Pitch

1/2” Pitch (BS Standard Roller Chain)

Tooth Count Options

8T to 50T+

Material

C45 Steel / Hardened Steel

Bore Type

Pilot Bore (Machinable to Required Shaft Size)

Mounting Style

Direct Shaft, Hub, or Bushing Mount

Tooth Profile

British Standard (BS / ISO Chain)

Applications

Industrial, Agricultural, Conveyor, Mechanical Drives

Finish

Untreated / Phosphate / Black Oxide (model dependent)

Key Features & Benefits

  • Customizable Bore: Machine the bore and keyway exactly as required.
  • Smooth Power Transfer: Precisely machined teeth ensure accurate chain engagement.
  • High-quality Steel made: Any types of metal work, 5” Heavy Duty.
  • Large Size Range: Will work small equipment all the way up to large industrial machinery.
  • Also compatible with BS standard: Suits all 1/2" pitch standard roller chains.
  • Bulk order discount: Great for OEMs, garages and maintenance facilities.

Why Choose Bolton Engineering Products Ltd?

As one of the UK’s trusted suppliers of pilot bore sprockets, BEP Ltd offers:

  • Large inventory of plain bore sprockets in multiple tooth counts
  • High-quality components sourced from reliable manufacturers
  • Competitive prices with trade & bulk discounts
  • Expert technical support for sizing and application queries
  • Fast UK dispatch with reliable shipping options

When you need precision, durability, and flexibility, BEP Ltd has the right pilot bore sprocket for your job.

FAQs

Q1: What is the difference between a pilot bore sprocket and a finished bore sprocket?

A pilot bore sprocket has an oversized bore that requires machining. A finished bore sprocket comes pre-machined to a specific shaft size.

Q2: Is a pilot bore the same as a plain bore?

Yes — plain bore sprockets and pilot bore sprockets describe the same unfinished, machinable bore design.

Q3: Can I machine the bore myself?

Yes. Many customers machine the bore, keyway, and grub-screw holes in-house. We can also advise on machining allowances.

Q4: Are these sprockets compatible with standard roller chains?

Absolutely. All our sprockets fit 1/2” pitch BS roller chains.

Roller Chain Pilot Bore Sprockets - 1/2"

Pilot Bore Sprockets – 1/2” Pitch Roller Chain Sprockets

At Bolton Engineering Products Ltd, we stock a full range of pilot bore sprockets designed for reliable, efficient power transmission in machinery, conveyors, automation systems, and chain-driven equipment.

These plain bore sprockets (Type A) have an unprepared bore and require a keyway and set screw for installation, allowing them to be fully customized to fit any shaft size and meet your specific needs.

BEP Ltd have you covered – whether it be a light-duty sprocket or an item designed for continuous use, all our parts are made from high-strength materials and custom machined to tight tolerances at very competitive prices.

What Is a Pilot Bore Sprocket?

A pilot bore sprocket is a chain sprocket supplied with a basic, oversized bore, allowing engineers or machinists to finish-machine it to the exact shaft diameter or keyway required.

These sprockets are popular in:

  • Manufacturing & processing equipment
  • Agricultural and industrial machinery
  • Conveyors and material handling systems
  • Motorcycles, bicycles & chain-driven vehicles
  • General engineering and fabrication workshops

Their flexibility makes them a go-to choice for custom drive systems and OEM applications.

Technical Specifications

Specification

Details

Product Type

Pilot Bore / Plain Bore Sprocket

Chain Pitch

1/2” Pitch (BS Standard Roller Chain)

Tooth Count Options

8T to 50T+

Material

C45 Steel / Hardened Steel

Bore Type

Pilot Bore (Machinable to Required Shaft Size)

Mounting Style

Direct Shaft, Hub, or Bushing Mount

Tooth Profile

British Standard (BS / ISO Chain)

Applications

Industrial, Agricultural, Conveyor, Mechanical Drives

Finish

Untreated / Phosphate / Black Oxide (model dependent)

Key Features & Benefits

  • Customizable Bore: Machine the bore and keyway exactly as required.
  • Smooth Power Transfer: Precisely machined teeth ensure accurate chain engagement.
  • High-quality Steel made: Any types of metal work, 5” Heavy Duty.
  • Large Size Range: Will work small equipment all the way up to large industrial machinery.
  • Also compatible with BS standard: Suits all 1/2" pitch standard roller chains.
  • Bulk order discount: Great for OEMs, garages and maintenance facilities.

Why Choose Bolton Engineering Products Ltd?

As one of the UK’s trusted suppliers of pilot bore sprockets, BEP Ltd offers:

  • Large inventory of plain bore sprockets in multiple tooth counts
  • High-quality components sourced from reliable manufacturers
  • Competitive prices with trade & bulk discounts
  • Expert technical support for sizing and application queries
  • Fast UK dispatch with reliable shipping options

When you need precision, durability, and flexibility, BEP Ltd has the right pilot bore sprocket for your job.

FAQs

Q1: What is the difference between a pilot bore sprocket and a finished bore sprocket?

A pilot bore sprocket has an oversized bore that requires machining. A finished bore sprocket comes pre-machined to a specific shaft size.

Q2: Is a pilot bore the same as a plain bore?

Yes — plain bore sprockets and pilot bore sprockets describe the same unfinished, machinable bore design.

Q3: Can I machine the bore myself?

Yes. Many customers machine the bore, keyway, and grub-screw holes in-house. We can also advise on machining allowances.

Q4: Are these sprockets compatible with standard roller chains?

Absolutely. All our sprockets fit 1/2” pitch BS roller chains.

4SR13-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-13-Tooth

4SR13 (08B-1-13) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 13 Tooth

£14.53 - £14.53
£14.53
£14.53 - £14.53
£14.53

4SR13 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR13 Pitch 1/2 Teeth 13 Outside...

View full details
£14.53 - £14.53
£14.53
£14.53 - £14.53
£14.53
4SR17-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-17-Tooth

4SR17 (08B-1-17) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 17 Tooth

£18.06 - £18.06
£18.06
£18.06 - £18.06
£18.06

4SR17 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR17 Pitch 1/2 Teeth 17 Outside...

View full details
£18.06 - £18.06
£18.06
£18.06 - £18.06
£18.06
4SR18-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-18-Tooth

4SR18 (08B-1-18) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 18 Tooth

£20.06 - £20.06
£20.06
£20.06 - £20.06
£20.06

4SR18 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR18 Pitch 1/2 Teeth 18 Outside...

View full details
£20.06 - £20.06
£20.06
£20.06 - £20.06
£20.06
4SR21-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-21-Tooth

4SR21 (08B-1-21) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 21 Tooth

£26.88 - £26.88
£26.88
£26.88 - £26.88
£26.88

4SR21 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR21 Pitch 1/2 Teeth 21 Outside...

View full details
£26.88 - £26.88
£26.88
£26.88 - £26.88
£26.88
4SR22-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-22-Tooth

4SR22 (08B-1-22) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 22 Tooth

£28.60 - £28.60
£28.60
£28.60 - £28.60
£28.60

4SR22 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR22 Pitch 1/2 Teeth 22 Outside...

View full details
£28.60 - £28.60
£28.60
£28.60 - £28.60
£28.60
4SR23-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-23-Tooth

4SR23 (08B-1-23) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 23 Tooth

£29.64 - £29.64
£29.64
£29.64 - £29.64
£29.64

4SR23 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR23 Pitch 1/2 Teeth 23 Outside...

View full details
£29.64 - £29.64
£29.64
£29.64 - £29.64
£29.64
4SR25-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-25-Tooth

4SR25 (08B-1-25) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 25 Tooth

£32.25 - £32.25
£32.25
£32.25 - £32.25
£32.25

4SR25 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR25 Pitch 1/2 Teeth 25 Outside...

View full details
£32.25 - £32.25
£32.25
£32.25 - £32.25
£32.25
4SR26-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-26-Tooth

4SR26 (08B-1-26) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 26 Tooth

£36.31 - £36.31
£36.31
£36.31 - £36.31
£36.31

4SR26 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR26 Pitch 1/2 Teeth 26 Outside...

View full details
£36.31 - £36.31
£36.31
£36.31 - £36.31
£36.31
4SR30-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-30-Tooth

4SR30 (08B-1-30) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 30 Tooth

£45.07 - £45.07
£45.07
£45.07 - £45.07
£45.07

4SR30 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR30 Pitch 1/2 Teeth 30 Outside...

View full details
£45.07 - £45.07
£45.07
£45.07 - £45.07
£45.07
4SR34-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-34-Tooth

4SR34 (08B-1-34) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 34 Tooth

£55.56 - £55.56
£55.56
£55.56 - £55.56
£55.56

4SR34 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR34 Pitch 1/2 Teeth 34 Outside...

View full details
£55.56 - £55.56
£55.56
£55.56 - £55.56
£55.56
4SR38-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-38-Tooth

4SR38 (08B-1-38) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 38 Tooth

£66.73 - £66.73
£66.73
£66.73 - £66.73
£66.73

4SR38 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR38 Pitch 1/2 Teeth 38 Outside...

View full details
£66.73 - £66.73
£66.73
£66.73 - £66.73
£66.73
4SR40-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-40-Tooth

4SR40 (08B-1-40) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 40 Tooth

£70.02 - £70.02
£70.02
£70.02 - £70.02
£70.02

4SR40 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR40 Pitch 1/2 Teeth 40 Outside...

View full details
£70.02 - £70.02
£70.02
£70.02 - £70.02
£70.02
4tr95-pilot-bore-08b-1-2-pitch-sprocket

4TR95 (08B-3-95) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 95 Tooth

£0.00 - £0.00
£0.00
£0.00 - £0.00
£0.00

4TR95 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR95 Pitch 1/2 Teeth 95 Outside Dia (mm) 390.1 ...

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£0.00 - £0.00
£0.00
£0.00 - £0.00
£0.00
4tr76-pilot-bore-08b-1-2-pitch-sprocket

4TR76 (08B-3-76) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 76 Tooth

£91.97 - £91.97
£91.97
£91.97 - £91.97
£91.97

4TR76 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR76 Pitch 1/2 Teeth 76 Outside Dia (mm) 313.3 ...

View full details
£91.97 - £91.97
£91.97
£91.97 - £91.97
£91.97
4tr57-pilot-bore-08b-1-2-pitch-sprocket

4TR57 (08B-3-57) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 57 Tooth

£58.95 - £58.95
£58.95
£58.95 - £58.95
£58.95

4TR57 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR57 Pitch 1/2 Teeth 57 Outside Dia (mm) 236.4 ...

View full details
£58.95 - £58.95
£58.95
£58.95 - £58.95
£58.95
4tr45-pilot-bore-08b-1-2-pitch-sprocket

4TR45 (08B-3-45) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 45 Tooth

£40.16 - £40.16
£40.16
£40.16 - £40.16
£40.16

4TR45 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR45 Pitch 1/2 Teeth 45 Outside Dia (mm) 188 ...

View full details
£40.16 - £40.16
£40.16
£40.16 - £40.16
£40.16
4tr40-pilot-bore-08b-1-2-pitch-sprocket

4TR40 (08B-3-40) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 40 Tooth

£32.75 - £32.75
£32.75
£32.75 - £32.75
£32.75

4TR40 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR40 Pitch 1/2 Teeth 39 Outside Dia (mm) 166.8 ...

View full details
£32.75 - £32.75
£32.75
£32.75 - £32.75
£32.75
4tr39-pilot-bore-08b-1-2-pitch-sprocket

4TR39 (08B-3-39) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 39 Tooth

£31.07 - £31.07
£31.07
£31.07 - £31.07
£31.07

4TR39 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR39 Pitch 1/2 Teeth 39 Outside Dia (mm) 162.7 ...

View full details
£31.07 - £31.07
£31.07
£31.07 - £31.07
£31.07
4tr38-pilot-bore-08b-1-2-pitch-sprocket

4TR38 (08B-3-38) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 38 Tooth

£29.97 - £29.97
£29.97
£29.97 - £29.97
£29.97

4TR38 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR38 Pitch 1/2 Teeth 38 Outside Dia (mm) 158.6 ...

View full details
£29.97 - £29.97
£29.97
£29.97 - £29.97
£29.97
4tr37-pilot-bore-08b-1-2-pitch-sprocket

4TR37 (08B-3-37) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 37 Tooth

£28.85 - £28.85
£28.85
£28.85 - £28.85
£28.85

4TR37 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR37 Pitch 1/2 Teeth 37 Outside Dia (mm) 154.6 ...

View full details
£28.85 - £28.85
£28.85
£28.85 - £28.85
£28.85
4tr36-pilot-bore-08b-1-2-pitch-sprocket

4TR36 (08B-3-36) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 36 Tooth

£27.89 - £27.89
£27.89
£27.89 - £27.89
£27.89

4TR36 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR36 Pitch 1/2 Teeth 36 Outside Dia (mm) 151 ...

View full details
£27.89 - £27.89
£27.89
£27.89 - £27.89
£27.89
4tr35-pilot-bore-08b-1-2-pitch-sprocket

4TR35 (08B-3-35) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 35 Tooth

£25.67 - £25.67
£25.67
£25.67 - £25.67
£25.67

4TR35 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR35 Pitch 1/2 Teeth 35 Outside Dia (mm) 146.7 ...

View full details
£25.67 - £25.67
£25.67
£25.67 - £25.67
£25.67
4tr34-pilot-bore-08b-1-2-pitch-sprocket

4TR34 (08B-3-34) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 34 Tooth

£24.70 - £24.70
£24.70
£24.70 - £24.70
£24.70

4TR34 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR34 Pitch 1/2 Teeth 34 Outside Dia (mm) 142.6 ...

View full details
£24.70 - £24.70
£24.70
£24.70 - £24.70
£24.70
4tr32-pilot-bore-08b-1-2-pitch-sprocket

4TR32 (08B-3-32) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 32 Tooth

£22.55 - £22.55
£22.55
£22.55 - £22.55
£22.55

4TR32 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR32 Pitch 1/2 Teeth 32 Outside Dia (mm) 134.3 ...

View full details
£22.55 - £22.55
£22.55
£22.55 - £22.55
£22.55

Hi. Need any help?