Description
TS7Z25×55 Locking Assembly – 25mm Shaft 55mm OD Keyless Rigid Shaft-Hub Connector
The TS7Z25×55 addresses the highly standardised 25 mm shaft size common in IEC frame 112 and 132 motors across global industrial applications. The 0.315 kN·m torque rating, 25.2 kN axial force capacity, and 91 MPa surface pressure at 17 N·m installation torque make this one of the most application-matched models in the TS7Z series for general industrial drive connections. 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 — 91 MPa for the TS7Z25×55 at the specified M_a of 17 N·m — generates a friction connection that transmits both torque (Mt = 0.315 kN·m) and axial force (Ft = 25.2 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 | TS7Z25×55 |
| Type | Locking Assembly (Keyless Shaft-Hub Connection) |
| Shaft Bore (d) | 25 mm |
| Outer Diameter (D) | 55 mm |
| Rated Axial Force (Ft) | 25.2 kN |
| Rated Torque (Mt) | 0.315 kN·m |
| Surface Pressure (Ps) | 91 MPa |
| Installation Screw Torque (Ma) | 17 N·m |
| Mass (G) | 0.77 kg |
| Material | Steel |
| Standard | GB/T 5106 compatible |
Dimensional Reference
Structural Cross-Section
Installation and Design Guidance
Installation of the TS7Z25×55 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 = 17 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 (91 MPa) ≤ 0.9 × shaft yield strength. For C45 steel (yield ~370 MPa): 0.9 × 370 = 333 MPa > 91 MPa — acceptable. For aluminium alloy 6061-T6 (yield ~275 MPa): 0.9 × 275 = 247 MPa; compare with 91 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
★★★★★
Malaysia — Mining & Mineral Processing
We specify the TS7Z25×55 for crusher drive shaft connections in our hard rock mining operations. The locking assembly’s published radial force capacity and the known surface pressure on the shaft allow us to design to a traceable standard rather than relying on empirical keyway sizing rules.
— Engineering Director, Kuala Lumpur
★★★★★
Indonesia — Metallurgical Equipment
Installed on billet rolling mill drive connections. The TS7Z25×55 handles the peak torque during cobble-clearing operations — a significant shock load above normal rolling torque — without slip. The locking assembly’s frictional connection distributes this shock load evenly rather than transmitting it through a key contact point.
— Applications Specialist, Jakarta
★★★★☆
Thailand — Quarrying & Aggregates
The TS7Z25×55 is used in primary jaw crusher drive connections at our quarry. The cyclic shock loading of jaw crushing operations is handled by the locking assembly’s high preload friction without any evidence of progressive slip or position change over our 12-month inspection interval.
— Design Engineer, Bangkok
Frequently Asked Questions
Can the TS7Z be used in high-temperature environments?
The TS7Z is made from steel with standard industrial surface treatment. It can operate continuously up to approximately 120°C. For higher temperatures, consult Ever Power for material and lubrication guidance. Thermal cycling can affect preload if shaft and hub materials have different thermal expansion coefficients.
How does the TS7Z locking assembly compare to a keyed connection?
A locking assembly distributes torque and axial force uniformly around the shaft circumference through friction, eliminating the stress concentration of a keyway. This typically allows the same torque to be transmitted through a smaller shaft diameter, or significantly extends fatigue life at the same shaft size. Locking assemblies also allow precise angular positioning, which is not possible with a keyed connection unless the keyway is machined to a specific angular reference.
Is the TS7Z available in stainless steel?
The standard TS7Z locking assembly is manufactured in steel with a standard surface treatment for industrial environments. For corrosion-resistant requirements, contact Ever Power to discuss material alternatives or protective coating options for your specific application.
Can the TS7Z be installed and removed without special tools?
Installation requires only a calibrated torque wrench with the correct hex key bit for the clamping screws. Removal is performed by loosening the clamping screws in a star pattern — the tapered ring geometry produces a self-releasing action as the screws are backed off. No hydraulic or heating tools are required for standard installations.
Does the TS7Z require periodic retightening?
In normal operating conditions with the correct installation torque applied, retightening is not required between scheduled maintenance intervals. However, installations subject to sustained vibration, thermal cycling, or repeated load reversal transients should have the clamping screw torque verified at the first scheduled maintenance after initial installation.
Source the TS7Z25×55 Locking Assembly
Ever Power manufactures the TS7Z25×55 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.