Product Description
The Martin 40B21 is a Type B single-strand roller chain sprocket designed for use with #40 ANSI roller chain (1/2" pitch). It features a plain stock bore of 5/8" that can be re-bored to a maximum of 1-7/8" to accommodate standard keyseats and setscrews. Manufactured from high carbon steel with solid construction, this sprocket meets or exceeds ANSI standards and is engineered with bores concentric to the pitch line to minimize runout in power transmission applications.
Technical Specifications
| Specification | Value |
|---|---|
| Brand | Martin Sprocket & Gear |
| Model / Part Number | 40B21 |
| Product Type | Roller Chain Sprocket |
| Chain Number | #40 |
| Chain Pitch | 1/2" (0.500 in) |
| Number of Teeth | 21 |
| Hub Type | B (Hub One Side) |
| Number of Strands | Single (1) |
| Outside Diameter | 3.617 in |
| Pitch Diameter | 3.355 in |
| Caliper Diameter | 3.03 in |
| Hub Diameter | 2.750 in (2-3/4") |
| Stock Bore Diameter (Min) | 5/8" (0.625 in) |
| Maximum Bore Diameter | 1-7/8" (1.875 in) |
| Length Through Bore | 1.000 in |
| Hub Length Through Bore | 0.716 in |
| Tooth Width (Single Strand) | 0.284 in |
| Bore Type | Stock / Plain Bore (Reborable) |
| Keyway | No Keyway or Setscrew (stock) |
| Hardened Teeth | No |
| Construction | Solid |
| Material | High Carbon Steel |
| Weight | 1.73 lbs |
| ANSI Standard | ANSI B29.1 |
We warranty all items for 30 days from date of purchase.
Other Details
We warranty all items for 30 days from date of purchase. If you experience any issues with your item within this period, please contact us and we will work with you to resolve the problem. This warranty covers defects in functionality but does not cover damage caused by misuse, improper installation, or normal wear and tear.Product Videos
Custom Field
GTIN 679523686185
Hole Diameter 3.03 in
Material High Carbon Steel
Diameter 3.03 in
Manufacturer Martin
Empty Weight 1.73 lbs
Part Number 40B21
Series B
Shelf GS 38
Bore Diameter 0.625 in (5/8" stock bore)
Model 40B21
MPN 40B21
Type Roller Chain Sprocket
