Z12 Type Locking Assembly(JB/T 7934‑1999)
Z12 Type Shrink Disc is a super‑heavy‑duty external‑clamping keyless locking device complying with JB/T 7934‑1999 standard. The whole shrink disc is mounted on the outer surface of the hub without direct contact with the drive shaft. A large number of 12.9‑grade high‑strength outer‑ring screws compress the conical rings. The conical rings shrink radially inward to squeeze the hub, clamping the hub firmly onto the shaft for transmitting ultra‑high torque and combined torque‑axial loads.
Main Features
‑ External‑clamping design, specially developed for large‑size thin‑wall hubs, prevents hub cracking during mounting.
‑ Maximum torque capacity within external‑clamping series. Available for single‑unit installation or multiple‑units series connection for extreme heavy‑duty conditions.
‑ Equipped with full‑set 12.9‑grade high‑strength hexagon socket screws. Tighten screws diagonally in several steps and strictly follow specified torque values.
‑ Keyless connection eliminates shaft strength reduction caused by keyway. Angular position can be adjusted freely. Non‑destructive assembly and disassembly for repeated use.
‑ Excellent resistance to shock load and frequent forward‑reverse rotation. Over‑load slipping protects costly drive components.
‑ Superior self‑centering performance, low radial run‑out during operation.
Structural note: Z1‑Z5 fit between shaft and hub; Z7, Z11 and Z12 shrink discs are fitted on hub outer diameter. Distinguish structure before selection.
Recommended Machining Tolerances
‑ Shaft：h7 / h8
‑ Hub bore：H7 / H8
‑ Mating surface roughness：Rz ≤ 16 μm
Applications：Extra‑large drums, main metallurgical machinery, mine main transmission, heavy gearbox output ends, large rollers, big‑size fans, heavy papermaking machinery, heavy mixing equipment.