Description
TS7Z42×78 Locking Assembly – 42mm Shaft 78mm OD Keyless Rigid Shaft-Hub Connector
The TS7Z42×78 covers the 42 mm shaft size found in certain European standard motors and heavy-duty gearbox output shafts. The slight OD increase to 78 mm provides additional ring wall section compared to the 75 mm OD models at a closely adjacent bore size, supporting the 64 MPa surface pressure rating with an adequate safety margin in standard steel shaft materials. For a complete listing of all TS7Z locking assembly models, visit our product catalog.
The TS7Z locking assembly operates on the principle of tapered ring compression: two tapered steel rings — inner and outer — are drawn together axially by the clamping screws. The taper geometry converts axial screw preload into a radial clamping force, expanding the inner ring against the shaft surface and contracting the outer ring against the hub bore simultaneously. The resulting surface pressure — 64 MPa for the TS7Z42×78 at the specified M_a of 42 N·m — generates a friction connection that transmits both torque (Mt = 0.624 kN·m) and axial force (Ft = 31.2 kN) without any mechanical interlock element. No keyway is required in either the shaft or the hub bore.
The elimination of the keyway is the principal engineering advantage of the TS7Z over traditional keyed hub connections. A keyway introduces a stress concentration at its corners that can initiate fatigue cracks under the cyclic torsion loading of a rotating drive — particularly at high surface hardness or in applications with frequent torque reversals. The TS7Z distributes torque loading uniformly around the full circumference of the shaft bore, eliminating this stress riser and significantly extending the fatigue life of the connected shafts. For high-cycle, high-torque drives — mills, fans, compressors, and crushers — this durability improvement is a primary selection rationale.
Technical Specifications
| Parameter | Value |
|---|---|
| Model | TS7Z42×78 |
| Type | Locking Assembly (Keyless Shaft-Hub Connection) |
| Shaft Bore (d) | 42 mm |
| Outer Diameter (D) | 78 mm |
| Rated Axial Force (Ft) | 31.2 kN |
| Rated Torque (Mt) | 0.624 kN·m |
| Surface Pressure (Ps) | 64 MPa |
| Installation Screw Torque (Ma) | 42 N·m |
| Mass (G) | 1.33 kg |
| Material | Steel |
| Standard | GB/T 5106 compatible |
Dimensional Reference
Structural Cross-Section
Installation and Design Guidance
Installation of the TS7Z42×78 requires the shaft surface to be clean, dry, and within an h6 or k6 shaft tolerance, with a surface finish of Ra 0.8–1.6 μm. The hub bore should be machined to H7 tolerance. Clamping screw threads and head bearing faces must be lubricated with MoS₂ paste before installation to ensure the M_a = 42 N·m tightening torque produces the correct clamping force. Tighten all screws in a star pattern in at least three progressive passes — do not fully tighten one screw before the others.
To verify shaft material suitability, check: Ps (64 MPa) ≤ 0.9 × shaft yield strength. For C45 steel (yield ~370 MPa): 0.9 × 370 = 333 MPa > 64 MPa — acceptable. For aluminium alloy 6061-T6 (yield ~275 MPa): 0.9 × 275 = 247 MPa; compare with 64 MPa for this model. If the shaft material yield strength is insufficient, contact our contact our team for a re-rated configuration.
Keyless Design
No keyway in shaft or hub. Eliminates keyway stress concentration and fretting wear. Angular position can be set freely — no keyway angular constraint.
Self-Releasing Disassembly
Back off clamping screws in a star pattern — the taper geometry produces a self-releasing action requiring no extraction tools or heat. Shaft and hub surfaces are undamaged after removal.
Uniform Load Distribution
Torque is transmitted through friction uniformly around the full shaft circumference, distributing stress evenly and enabling the same torque to be carried at lower peak shaft stress than a keyed connection.
Bidirectional Torque
Frictional connection transmits equal torque in both rotational directions. No directional constraint — suitable for reversing drive applications without additional design consideration.
Customer Reviews and Case Studies
★★★★★
Italy — Agricultural Machinery OEM
Used in combine harvester threshing drum drive connections. The TS7Z42×78’s installation procedure via a calibrated torque wrench is straightforward for our field service teams and the locking assembly releases cleanly during drum overhaul without requiring specialised extraction equipment.
— Mechanical Engineer, Turin
★★★★★
France — Food & Beverage Processing
Installed on conveyor drive shaft connections in our bottling plant. The TS7Z42×78 allowed installation by our maintenance team using only standard torque tools. The published surface pressure of 64 MPa was used to verify shaft suitability in our design review, which is not possible with conventional keyed connections.
— Applications Engineer, Lyon
★★★★☆
Finland — Wood Processing Equipment
The TS7Z42×78 is installed on chipper disc drive shaft connections at our wood processing facility. The locking assembly handles the high-energy shock loads from disc chipping operations without slip. The 1.33 kg mass is manageable by our two-person maintenance team without lifting equipment.
— Senior Engineer, Tampere
Frequently Asked Questions
Does the TS7Z locking assembly require a keyway in the shaft?
No. This is a primary advantage of the locking assembly design. The shaft requires only a plain, ground cylindrical surface within the bore tolerance — no keyway machining is required. This eliminates the keyway stress concentration and simplifies shaft manufacturing.
What is the Ps (surface pressure) parameter and how is it used?
Ps is the radial contact pressure between the inner ring and the shaft surface at the specified installation torque. It is used to verify that the shaft material’s yield strength is not exceeded. The design rule is: Ps must be less than 0.9 × yield strength of the shaft material. For mild steel shafts (yield ~250 MPa), Ps must be below 225 MPa.
What is the Ft (axial force) capacity of the TS7Z?
Ft is the maximum axial force the locking assembly can resist at the specified installation torque. In most applications, the combined torque and axial force loading must be checked against the rated values — if both torque and axial force act simultaneously, the effective capacity of each is reduced proportionally. Consult the interaction formula provided in the product documentation.
What is the maximum shaft diameter for the TS7Z series?
The TS7Z series covers shaft bore diameters from 15 mm (TS7Z15×45) to 110 mm (TS7Z110×160). If a shaft diameter outside this range is required, contact Ever Power to discuss alternative locking assembly series that may cover your requirement.
Is the TS7Z suitable for use in explosive atmospheres (ATEX)?
The TS7Z is a mechanical component and does not carry an ATEX electrical rating. The steel body has low spark risk from mechanical contact, and locking assemblies are commonly used in ATEX Zone 1 and Zone 2 machinery. Confirm the overall machine ATEX certification requirements with your safety engineer and Ex certification body.
Source the TS7Z42×78 Locking Assembly
Ever Power manufactures the TS7Z42×78 and the complete TS7Z locking assembly series — 31 bore sizes from 15 mm to 110 mm — direct from our factory. Provide your shaft diameter, hub bore, application torque, and quantity for a prompt technical review and factory-direct pricing.