DWH Technical Topic: Dancer cylinders

By Clarence Klassen, P. Eng. 

I recently came across a case where a dancer could not provide enough force to establish rated web tension. The cylinder had to lift the tare weight of the roller plus provide the required tension force. The cylinder was mounted such that the rod side had to be pressurized to lift the roller. The rod side has less surface area and thus less force is available.

The two possible solutions were to invert the dancer cylinders to get a bit more force or to use larger cylinders. In this case, the supplier opted for larger cylinders. That provided more than enough force. The pressure was reduced from 5 bar to 1.5 bar. However, the larger cylinder had more stiction, so tension control was not ideal.

Image: Yellow Submarine Original Artwork. Copyright 2014