Sprocket 20B-2 z=57 with hub, Cast iron

Product Description

Sprocket 20B-2 z=57, with cast iron hub

Duplex sprocket 20B-2 with hub, 57 teeth - designed for chain with a pitch of 1 1/4" (31.75 mm). Cast iron version of the sprocket - the tooth geometry is identical to the steel version with the same pitch and number of teeth; the bore in the hub is a pilot (preliminary) bore, and the exact size is achieved by turning.

Technical data

Frequently asked questions

Why are cast sprockets less precise than turned and milled ones?

Cheap castings have a rough tooth surface, hidden air bubbles and slight deformations. CNC-turned and milled sprockets mean a smooth working surface, perfect alignment and safety for the most expensive machines.

How does uneven tooth wear affect machine vibration?

Worn teeth cause the so-called polygon effect - the chain drops off and climbs onto the teeth abruptly, which transmits vibrations to the shafts, destroys the bearings and leads to cracking of welds in the machine.

How can you recognise an idler sprocket bearing that is starting to wear before it fails?

The first symptom is usually increased noise and noticeable, excessive play of the sprocket when it is moved by hand with the machine stopped. It is also worth periodically checking the temperature of the bearing housing during operation - an increase compared with other bearings in the system signals progressive wear.

What is the set screw hole in the hub for?

The threaded hole in the hub is used to screw in a headless screw (a so-called grub screw). It secures the sprocket against axial displacement along the shaft during machine vibration.

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.

Does a cast iron sprocket require a different chain than a steel sprocket of the same pitch?

No - the tooth geometry and pitch are identical to those of the steel version of the same size, so the cast iron sprocket works with the same chain. The difference lies in the material of the hub and rim: cast iron dampens vibrations better and is cheaper, but withstands impacts and operation at high rotational speeds less well than steel.

Where is this product used?

This type of sprocket is used in drives of agricultural and industrial machinery, including screw and bucket conveyors, feed conveyors, packaging machines and internal transport systems.

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.