Sprocket 20B-2 z=21 with hub, hardened

Product Description

Sprocket 20B-2 z=21, hardened hub

Sprocket 20B-2 (pitch 1 1/4" - 31.75 mm), duplex, 21 teeth, with hardened hub. Sprocket compliant with DIN 8187 / ISO 606, milled from C45E steel (EN 10083-1); the teeth are induction hardened (45-55 HRC), while the core and hub remain soft, allowing the bore to be safely machined to the shaft size.

Technical data

Frequently asked questions

What causes premature wear of the side faces of the teeth?

This is most often the result of misalignment of the sprockets on the shafts (so-called lateral runout of the drive). The chain does not run straight, and its inner plates catch on the sides of the teeth, wearing them down to bare metal. The system must be realigned immediately.

How do I bore the hole in a sprocket to fit a motor shaft?

A sprocket with a pilot bore should be clamped in a lathe (gripping the hub to avoid runout) and bored to the required diameter with an H7 tolerance. If the sprocket has hardened teeth, the hub is usually soft and easy to machine.

When should I choose a sprocket with hub and when a flat one (plate wheel)?

Flat sprockets (plate wheels) are most often used where they are mounted onto an existing flange or drum, or when there is extremely little space on the shaft. We choose a sprocket with hub when it must reliably transmit high torque directly from the shaft via a key - the hub provides a longer contact surface.

Is a duplex sprocket the same as a tandem sprocket (for two single chains)?

No, even though they look very similar. A tandem sprocket is also a single, monolithic sprocket, but with a different (wider) spacing of the toothed rims - designed specifically for two independent simplex chains running in parallel. This duplex sprocket has a rim spacing matched to a single duplex chain, in which both strands are integrated with each other. Using a duplex sprocket for two single chains is a mistake - the spacing is too narrow and the chains will rub against each other, which leads to accelerated wear and, in extreme cases, to serious drive failure.

Where is this product used?

Typical applications of the 20B-2 sprocket: drives for pumps, mixers and industrial fans, as well as control systems for industrial gates and roller shutters, where resistance to continuous operation is required.

When placing your order, please check the current stock level of this gear - the lead time depends on it and is clearly stated according to the quantity available in the given warehouse.

Product photos are for illustrative purposes only.