Product Description:

The 04.17.670-120U is a spring-applied, electrically released brake from KEB’s Combistop Spring Brakes series. It is mounted between a motor and load to generate static holding force and controlled torsional stopping in automated machinery. By clamping the shaft whenever power is removed, the unit prevents unintended motion and supports fail-safe positioning within conveyors, hoists, and general drive systems.

This model develops a rated holding torque of 16.5 Nm and is designed for a 100% duty cycle, so it can stay engaged continuously without thermal derating. Fast engagement is possible in direct-current drive circuits, where the armature seats in 35 ms; in alternating-current applications, the same action is completed in 145 ms. The release time on an AC supply is limited to 65 ms, allowing predictable restart sequences during cycling. The pilot diameter is 4.500 in, and the bolt circle spans 5.875 in, providing a centered interface that aligns with standard NEMA or IEC motor flanges. Coupling integrity is maintained by a bolt torque of 17.5 lb-ft, while the hub is secured to the shaft with a set-screw torque of 3.7 lb-ft. Axial and radial alignment limits are tight; flange runout may not exceed 0.004 in TIR, and shaft runout is capped at 0.002 in TIR.

Dynamic operation is supported by a rotor inertia of 1.3 × 10^-4 kg·m², which minimizes the additional load during drive acceleration. The brake can absorb up to 3.5 × 10³ J during a single stop, while continuous operation is restricted to 100 J/s to prevent the lining from overheating. The bearing system tolerates a maximum overhung load of 83 lb, so pulley or sprocket side loads must remain within this limit. Its overall length is 3.500 in, allowing installation in compact gear-motor assemblies without spacer modifications.