The KH2 Series from Berg Spanntechnik is a 2-jaw wedge-bar power chuck engineered for high-speed lathe turning where both heavy roughing cuts and precision finishing passes are performed on the same machine. Unlike conventional draw-tube power chucks that lose clamping force at elevated RPM due to centrifugal jaw lift-off, the KH2 eliminates this problem at the design level — not through add-on compensation — making it suitable for sustained operation at speeds up to 8,000 rpm.

How does the wedge-bar design eliminate centrifugal force loss?

In a wedge-bar chuck, the hydraulic piston drives wedge-shaped bars — two per base jaw — that translate axial piston movement into radial jaw clamping. The critical design choice is mass reduction: every centrifugally loaded component in the jaw drive train is minimized, and the wedge geometry provides a mechanical advantage that resists jaw lift-off. The result is a chuck that maintains consistent clamping force across its entire speed range without needing the counterweights, levers, or spring packs that conventional centrifugal compensation systems rely on. A secondary benefit is the absence of clamping force hysteresis — the chuck does not overshoot and potentially deform thin-walled workpieces during the clamping stroke.

Which mount type do I need?

The KH2 is offered in two spindle interface configurations. KH2-A uses the DIN 55026 short taper mount system, the standard for European CNC lathe spindles, with bolt circle dimensions matched to the spindle nose size (A4 through A8). KH2-Z uses a cylindrical flat flange mount for machines with flat spindle noses — common on certain Japanese and Taiwanese lathe brands. Clamping force, speed rating, and weight are identical across mount types for a given size; only the rear interface geometry differs.

Size selection