COMPENSATING CHAIN SPROCKET

How a compensating drive sprocket works:

The chordal action of long-pitch chains usually subjects the conveyor and its driving parts to an additional load of speed-ups and slow-downs. This occurs because of the rise and fall of the chain as it enters the sprocket. Although this chordal action cannot be eliminated, its effect can be cancelled through the use of a compensating sprocket mounted on the conveyor head shaft.

When the chain pivot approaches the top of the sprocket the pitch diameter and the speed of the chain is at its highest. The rotational revolutions of the sprocket remain the same but the chain slows down due to the changing of the chain pull diameter. Because of this, the effective pull diameter increases and decreases during this rotation.

The compensating sprocket is used to counteract the speed difference of the chain. To offset this pitch diameter change which effects of the chain speed, the compensating sprocket will increase and decrease the driven chain speed. This is accomplished by using the same increasing and decreasing of the drive sprocket. This will in turn adversely counteract the conveyor chain speed.

As the conveyor chain raises on the conveyor sprocket and increases the rotational speed, the driven chain sprocket will fall and reduce the speed. This is the counter action required to maintain a more consistent chain speed.

When the chordal action of the conveyor sprocket drives the conveyor at its fastest rate, the compensating sprocket will drive the conveyor chain at a slower rate. When the chordal action drives the conveyor at its slowest rate, the compensating sprocket will drive the head shaft at a faster rate. The difference between the speeds is significant considering the mass of the conveyor parts plus the mass of the material being conveyed. This change will greatly reduce the surging of the conveyor chain.

The drawing shows how a compensating drive sprocket and the chain pitch diameter changes in speed.