An idler sprocket is sprocket which serves only to transmit rotation from one shaft to another, in applications where it is undesirable to connect them directly. For example, connecting a motor to the platter of a phonograph, or the crankshaft-to-camshaft gear train of an automobile.

Because it does no work itself, it is called an "idler". 

For idler sprockets, there always have to press into something, such as bearing, bronze bushing, etc. To press the bearing or bushing into sprocket correctly is very important. Too loose or too tight all would caused quality problem,  

Our factory pay special attention to idler sprocket manufacture, especially the bearing/bushing assemble process.

Two videos showed how we press the bearing into the sprockets process, we process bearing into sprocket bore by Oil Press Machine.

The right process, the right quality control make the right sprocket.

..........om