Description
TS7Z20×50 Locking Assembly – 20mm Shaft 50mm OD Keyless Rigid Shaft-Hub Connector
The TS7Z20×50 is one of the most commonly specified models in the TS7Z small-bore range, addressing the widely standardised 20 mm motor shaft size (IEC frames 90 and 100). The 0.168 kN·m rated torque covers a broad range of fractional to 1 kW industrial drives, and the 95 MPa surface pressure is well within the capability of standard C45 shaft steel. 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 — 95 MPa for the TS7Z20×50 at the specified M_a of 17 N·m — generates a friction connection that transmits both torque (Mt = 0.168 kN·m) and axial force (Ft = 16.8 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 | TS7Z20×50 |
| Type | Locking Assembly (Keyless Shaft-Hub Connection) |
| Shaft Bore (d) | 20 mm |
| Outer Diameter (D) | 50 mm |
| Rated Axial Force (Ft) | 16.8 kN |
| Rated Torque (Mt) | 0.168 kN·m |
| Surface Pressure (Ps) | 95 MPa |
| Installation Screw Torque (Ma) | 17 N·m |
| Mass (G) | 0.5 kg |
| Material | Steel |
| Standard | GB/T 5106 compatible |
Dimensional Reference
Structural Cross-Section
Installation and Design Guidance
Installation of the TS7Z20×50 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 (95 MPa) ≤ 0.9 × shaft yield strength. For C45 steel (yield ~370 MPa): 0.9 × 370 = 333 MPa > 95 MPa — acceptable. For aluminium alloy 6061-T6 (yield ~275 MPa): 0.9 × 275 = 247 MPa; compare with 95 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
★★★★★
Mexico — Textile Machinery OEM
Specified for weaving machine main shaft connections. The TS7Z20×50 provides a vibration-resistant keyless connection that eliminates the micro-fretting wear we experienced with key-and-keyway connections under the high-cycle, low-amplitude vibration loading of our textile machinery.
— Technical Buyer, Monterrey
★★★★★
Japan — Printing Machine Manufacturing
Used in web offset printing press ink roller drive connections. The locking assembly’s zero-backlash rigid connection is essential for print registration accuracy — any shaft play would appear directly as registration error in the printed product. The TS7Z20×50 has maintained its position integrity through our planned maintenance disassembly cycles.
— Engineering Lead, Osaka
★★★★☆
Finland — Wood Processing Equipment
The TS7Z20×50 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 0.5 kg mass is manageable by our two-person maintenance team without lifting equipment.
— Senior Engineer, Tampere
Frequently Asked Questions
Is the TS7Z suitable for very low-speed, high-torque applications?
Yes. Locking assemblies are particularly well suited to low-speed, high-torque applications such as crusher drives, mill drives, and mixer agitators — where the torque per unit of shaft diameter is high and keyway fatigue is a concern. The TS7Z’s frictional connection distributes load uniformly without the stress concentration of a keyway.
What surface treatment is applied to the TS7Z?
The standard TS7Z locking assembly components are manufactured from steel with a phosphate or similar surface treatment that provides moderate corrosion protection during storage and in dry industrial environments. For outdoor or wet environments, additional protection such as periodic light oiling of external surfaces is recommended.
Can the TS7Z be used with aluminium hubs?
Yes, provided the aluminium hub material has sufficient yield strength to withstand the Ps contact pressure from the outer ring. For common aluminium alloys (e.g. 6061-T6, yield ~275 MPa; 7075-T6, yield ~500 MPa), the Ps value for the selected TS7Z model must be below 0.9 × hub material yield strength.
What is the difference between TS7Z Ma_small and Ma_large values?
Some TS7Z models list two M_a values corresponding to different screw sizes within the assembly. The smaller screws (inner ring) and larger screws (outer ring) may have different specified tightening torques. Always tighten all screws of the same size to the same specified torque and verify with the product documentation for your specific model.
How do I calculate whether the TS7Z is suitable for my application?
Three checks are required: (1) Mt ≥ application torque × safety factor; (2) Ft ≥ application axial force × safety factor; (3) Ps ≤ 0.9 × shaft material yield strength. A recommended safety factor of 1.5 to 2.0 should be applied to rated values. Contact Ever Power’s engineering team for a free application check if you have any uncertainty.
Source the TS7Z20×50 Locking Assembly
Ever Power manufactures the TS7Z20×50 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.