The Martin metric double, also known as a duplex, type B sprocket is suitable for use with the series ISO 12B-2/metric 50-2 chain with 19.05 mm (0.750”) pitch for driver or driven sprocket applications. Varying numbers of teeth and pitch diameters offer application flexibility. Made from high carbon steel, it has high strength and durability. Multiple chain capability allows for more power at higher operational speeds with greater load capacity.

Type B sprockets have a hub extension on one side to provide stability, and allow for the use of full-depth keyways and standard setscrews to attach the sprocket. They can also accommodate a wide range of shafts. The double style accepts two chains side-by-side.

The chain data for this class of sprockets is BS 228/13, ISO 12B-2; pitch is 19.05 mm (0.750”); roller diameter is 12.07 mm (0.475”); roller width is 11.68 mm (0.460”); and tensile strength is 5,900 kg (13,000 lb.).

The options for this class of sprocket are: number of teeth from 11 to 114; pitch diameter from 67.62 to 691.36 mm; stock bore size from 16 to 40 mm; maximum bore size from 32 to 93 mm; hub diameter from 47 to 140 mm; length through bore from 50 to 85 mm; and approximate weight from 1.00 to 41.86 kg. The face width (not including the hub) is 30.33 mm (1.194”). The chain row thickness is 10.87 mm (0.428”) nominal. Maximum bores will accommodate standard keyseat and setscrew over keyseat. Slightly larger bores are possible with no keyseat, shallow keyseat, or setscrew at angle to keyseat. All Martin sprockets meet or exceed ANSI standards.

A sprocket is a wheel with teeth around the perimeter that meshes with a chain, track, or other perforated or indented material. Unlike gears that mesh with another gear, sprockets mesh with a chain, which then interacts with another sprocket. Gears can be used to transmit power around a corner, based on how they fit together. Sprockets with chains only work in straight lines. Some common benefits of chain-drive systems include minimal slippage, a fixed ratio between rotating shafts, and versatility with many different chain attachments and sprocket material selections. An example of a power transmission system is a standard bicycle, which has a sprocket and a chain to deliver power from the rider’s legs to the wheels making the bike move.

Martin Sprocket & Gear manufactures power transmission and conveying products. The company was founded in 1951 and is headquartered in Arlington, TX. Martin provides tools that meet American National Standards Institute (ANSI), National Aerospace Standard (NAS), and Deutsches Institut für Normung (DIN) standards.