The maximum clamping moment of the power clamps GN 864 is reached once the clamping arm is at the end of its stroke. For this reason the working stroke should be completed as closely as possible to the stroke end. The type FG is equipped with an anti-stick coating of polytetrafluorethylene (PTFE) for protection against welding spray and corrosion. With protective covers GN 864.1 (see page ) the tensioning mechanism can be additionally protected against penetrating dirt.