RÖHM DURO-A 3-Jaw Wedge-Hook Power Chuck with Through-Hole for CNC Lathes

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Product Specifications

Brand: RÖHM
Part Number: DURO-A
Type: 3-Jaw Power Chuck
Clamping Mechanism: Wedge Hook
Sizes: 110, 135, 165, 210, 254, 315, 400 mm
Max. Clamping Force: 250 kN (Size 400)
Max. Speed: 8,500 rpm (Size 110)
Through-Hole: 27–133 mm (size-dependent)
Mounting: Cylindrical Center Mount (ZA) / Short Taper (DIN ISO 702-1)

Product Description

The RÖHM DURO-A is a three-jaw power chuck with through-hole, designed for automated CNC lathes and turning centers. It is the successor to the legacy KFD-HE and KFD-HS power chucks, delivering higher speed ratings, a reduced interference contour for automated machining, and full backward compatibility with existing KFD-series top jaws. The wedge-hook clamping mechanism is rated for over 500,000 cycles and is backed by a 36-month manufacturer warranty.

DURO-A Size Range and Technical Specifications

Parameter	110	135	165	210	254	315	400
Outer Diameter (mm)	110	135	165	210	254	315	400
Through-Hole (mm)	27	34	46	54	79	98.5	133
Jaw Stroke (mm)	3.2	3.2	3.5	4.5	5.5	6.2	7.5
Max. Clamping Force (kN)	48	70	86	110	150	180	250
Max. Speed (rpm)	8,500	8,000	8,000	6,500	5,000	4,200	3,150
Piston Stroke (mm)	12	12	13	17	20.5	23	28
Max. Operating Force (kN)	17	25	30	38	53	62	90
Weight (kg)	4.3	6.9	11.5	19.6	33	56.8	108.6

What makes the wedge-hook clamping mechanism durable?

The DURO-A uses a proven wedge-hook principle: an annular piston drives three wedge hooks that pull the base jaws inward, converting axial draw-tube force into radial clamping force. Unlike wedge-bar designs, the hook geometry distributes load across a larger contact surface, reducing wear at the force-transmission interface. RÖHM rates the mechanism for over 500,000 clamping cycles and backs it with a 36-month warranty — a durability benchmark in the power chuck market. The chuck body is also prepared for air sensing to confirm jaw closure before spindle start.

What mounting configurations are available?

The DURO-A is offered in two spindle interface options. The cylindrical center mount version (ZA) uses a 60° serration and is supplied with an intermediate flange for bolt-on installation to the machine spindle nose. The short taper mount version (DIN ISO 702-1) mounts directly to the spindle taper for higher concentricity and faster changeover. Both versions include a threaded ring ready-prepared for draw tube connection. Mounting screw patterns and centering diameters vary by size — from 3×M10 on the 110 to 3×M24 on the 400.

Are legacy KFD-series jaws compatible with the DURO-A?

Yes. The DURO-A base jaw interface is designed for full backward compatibility with KFD-HE and KFD-HS top jaws. Shops upgrading from the older KFD series can reuse their existing jaw inventory without modification. The standard DURO-A uses fixed base jaws with top jaws secured via T-nut bolts (M8 to M20 depending on chuck size). For shops requiring faster jaw changeover — under 60 seconds — the DURO-A RC variant adds individual jaw unlocking and straight-tooth base jaws with up to 17% weight reduction compared to conventional quick-change chucks in the same class.