Z7 Type Locking Assembly(JB/T 7934‑1999)
Z7 Type Shrink Disc is an external‑clamping keyless locking device complying with JB/T 7934‑1999 standard, including Z7A, Z7B and Z7C variants.
Different from Z1‑Z5 series locking assemblies which fit between shaft and hub, Z7 shrink disc mounts on the outer circumference of the hub, not directly touching the shaft. By tightening high‑strength screws, the conical rings compress the hub radially inward, so that the hub clamps firmly onto shaft to transmit torque and combined axial‑torque loads .
Main Features
‑ Specially designed for thin‑wall hub applications, avoid cracking thin‑walled hubs during installation.
‑ Very high torque capacity. Can be used single‑piece or multiple units connected in series for higher load performance.
‑ Equipped with 12.9 grade high‑strength hexagon socket screws. Tighten screws diagonally step‑by‑step following specified torque value.
‑ Keyless connection, eliminates shaft strength reduction caused by keyway. Angular position is freely adjustable before final tightening. Non‑destructive assembly & disassembly, reusable.
‑ Anti‑slip performance under shock load and frequent forward‑reverse rotation. Over‑load slipping protects expensive drive components.
‑ Excellent self‑centering performance, low vibration during operation.
Recommended Machining Tolerances
‑ Shaft：h7 / h8
‑ Hub bore：H7 / H8
‑ Mating surface roughness：Rz ≤16 μm
Applications：Large drums, metallurgical machinery, mining conveyors, heavy gearbox output ends, large rollers, coupling hubs, fans, paper‑making equipment.
Sub‑types brief
‑ Z7A: Standard basic version
‑ Z7B: More clamping screws for higher torque
‑ Z7C: Extended structure for maximum load capacity