The Schunk ROTA NCR-A sealed 6-jaw pendulum compensation chuck has special seals at the jaw interface and the piston to keep the grease from being washed out and the clamping force from being gradually lost.
 
The Schunk ROTA NCR-A consists of a central chuck piston, carrying three inner pendulums aligned at 120°. Each pendulum is connected to two base jaws. This ensures workpiece centering between six contact points, which can be adjusted in pairs. As the clamping forces are directed towards the chuck, optimum centering is achieved without redundant dimensioning of the workpiece. The chuck with its oscillating jaws perfectly adapts to the workpiece. In case of a conventional jaw clamping, this configuration ensures maximum roundness of the workpieces. 

The Schunk ROTA NCR-A is available in sizes from Ø 190 mm to Ø 1,000 mm with maximum clamping forces between 36 kN and 300 kN, and jaw strokes from 6 mm to 25 mm. The power lathe chucks of sizes 190 to 225 are equipped with tongue and groove; from size 250 it is equipped with a versatile fine serration (1.5 mm x 60° or 1/16'' x 90°). From size 630 on, the lathe chuck is prepared for the use on vertical lathes. Depending on the chuck size, the pendular compensation amounts between ± 1 mm and ± 6 mm, and the maximum speed is 600 rpm to 4,000 rpm.