Idler Sprocket

An idler sprocket rides along a roller chain to guide it, take up slack, or apply tension, without driving the chain itself. 3BG Supply stocks idler sprockets in single and double configurations, including ball-bearing designs, to pair with our roller chain sprockets and tensioners. Browse our full idlers and tensioners category or contact our team for help finding the right size.

Find the right Idler Sprocket for your needs.

  • Brand
  • Category
  • Chain Size
  • Bore / Inner Diameter Inch
  • Bore / Inner Diameter MM
  • Outside Diameter Inch
  • Outside Diameter MM
  • Type
  • Width Inch
  • Width MM
  • Length Thru Bore Inch
  • Length Thru Bore MM
  • Length MM
  • Pitch Inch
  • Pitch MM
  • Overall Length MM
  • Number of Teeth
  • Material
  • Pitch Diameter Inch
  • Pitch Diameter MM
  • Tooth Style
  • Rating
  • Hub Type
  • Hub Diameter Inch
  • Hub Diameter MM

    FAQs

    What is an idler sprocket?

    An idler sprocket is a free-spinning or fixed sprocket that rides along a roller chain to guide its path, take up slack, or maintain proper wrap around the drive and driven sprockets. Unlike a drive sprocket, it does not transmit power itself.

    What does an idler sprocket do in a chain drive?

    An idler sprocket keeps the chain properly seated and tensioned as it travels between the drive and driven sprockets, preventing the chain from sagging, jumping teeth, or wearing unevenly. It is especially useful in layouts with long center distances or multiple direction changes.

    What's the difference between an idler sprocket and a drive sprocket?

    A drive sprocket is mounted to a powered shaft and transmits torque into the chain, while a roller chain sprocket used as an idler simply guides or tensions the chain without adding power. Both use the same tooth profile so they mesh properly with the same chain.

    What is a ball bearing idler sprocket?

    A ball bearing idler sprocket has a sealed ball bearing built into its hub, allowing it to spin freely on a fixed shaft with minimal friction and reduced maintenance. This design is common in continuous-duty conveyor and drive applications.

    What is a double idler sprocket used for?

    A double idler sprocket has two sets of teeth mounted on a shared hub, allowing it to guide or tension two parallel chains at once, or to redirect a single chain in a compact space. It is commonly used in multi-strand conveyor and drive systems.

    How does an idler sprocket work with a chain tensioner?

    An idler sprocket is often mounted on a spring-loaded or adjustable arm as part of a tensioner assembly, so it can move to take up slack as the chain wears or stretches over time. This keeps the chain properly tensioned without manual adjustment.

    Industrial Idler Sprocket Manufacturers