Sprocket 20B-2 z=38 with hub, Cast iron

Product Description

Sprocket 20B-2 z=38, with cast iron hub

Sprocket 20B-2 with hub, 38 teeth, duplex - a product matched to chain with a pitch of 31.75 mm (1 1/4"). The material is grey cast iron - an economical solution with good vibration damping that proves itself in drives running at constant speed; the hub has a pilot bore that must be bored out individually to suit the shaft.

Technical data

Frequently asked questions

How long can a sprocket be kept in storage without losing its properties?

A properly preserved sprocket (dried, coated with grease or anti-corrosion oil, stored in a dry room) can be kept in storage for many years without any loss of its mechanical parameters. The only risk is surface corrosion due to improper storage - it does not affect the tooth geometry, but it is advisable to clean the sprocket and preserve it again before installation.

How do I determine the centre distance between the driving and driven sprockets?

The centre distance should provide an adequate chain wrap angle on the smaller sprocket (usually a minimum of about 120°) and sufficient chain length so that the number of links is a whole number, preferably even. Too small a centre distance increases the meshing frequency and accelerates wear, while too large a one leads to excessive chain sag.

How do I select a sprocket with bearing for a tensioning system?

An idler sprocket (with built-in bearing) is selected according to the pitch of the working chain and mounted on the slack side (not on the tight side). It is important that the bearing is protected against dust, especially in agricultural machinery.

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.

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?

20B-2 sprockets operate in drives of construction machinery, goods lifts, aggregate conveyors and woodworking machines - wherever tooth durability under load matters.

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.