Description
GT6 GT Type Sleeve Coupling – 56–80mm Bore Rigid Muff Coupling for Zero-Backlash Shaft Connection
The GT6 GT type sleeve coupling — also known as a muff coupling — is the simplest and most direct form of rigid shaft coupling: a single cylindrical steel body with a through bore machined to receive two co-linear shaft ends, transmitting torque through keyway and fitted key engagement on each shaft side. At 150 mm outer diameter and 302 mm overall length, the GT6 provides a compact, maintenance-free rigid connection for 56–80 mm shaft diameters, rated at 2500 N·m nominal torque at up to 3550 rpm maximum speed. Entering the large-bore GT class, the GT6 at 2,500 N·m covers 56–80 mm shaft connections typical of IEC frame 200 and 225 motors. Large centrifugal pump, fan, and industrial agitator drive connections are its primary application territory.
The operating principle of the GT sleeve coupling is direct and reliable. Each shaft end is inserted into one half of the sleeve bore. A fitted key is placed in the matching keyways of both the shaft and the sleeve bore on each side — two keys total, typically positioned 180° apart. When the coupling rotates, torque is transmitted from the driving shaft to the sleeve through key-keyway bearing contact, and from the sleeve to the driven shaft through the same mechanism on the opposite side. There are no flexible elements, no preloaded fasteners to maintain, and no wear surfaces subject to degradation under normal operating conditions. The result is a permanent, zero-backlash connection that requires essentially no maintenance throughout its service life, provided the connected shafts remain accurately aligned.
The H7 bore tolerance and GB3852-1997 keyway standard ensure dimensional compatibility with standard motor and driven equipment shaft ends throughout the GT series. For special shaft configurations — non-standard diameters, tapered bores, or hydraulic fit bores — custom machining is available. The complete GT series, from GT1 through GT10, is listed on our product catalog page.
Technical Specifications
| Parameter | Value |
|---|---|
| Model | GT6 |
| Type | GT Type Sleeve Coupling (Muff Coupling) |
| Bore Range (d) | 56–80 mm |
| Outer Diameter (D) | 150 mm |
| Overall Length (L) | 302 mm |
| Nominal Torque (Tn) | 2500 N·m |
| Maximum Speed [n] | 3550 rpm |
| Bore Tolerance | H7 standard |
| Keyway Standard | GB3852-1997 |
| Mass | 28.5 kg |
Dimension Reference
Construction and Functional Features
The GT6 body is machined from high-quality cast iron or cast steel — material selection dependent on model size and rated torque. The bore is machined to H7 tolerance to provide a controlled fit against the shaft end, complementing the key-keyway torque transmission with a stable radial contact between shaft and bore. The outer diameter is machined concentric with the bore to ensure rotational balance. Keyway slots are machined to GB3852-1997 standard dimensions for the specified bore size — verifying compatibility with standard motor shaft keyways without modification.
Zero Backlash
Rigid key-keyway torque transmission with no play or compliance — every angular increment on the driving shaft is replicated exactly on the driven shaft. Essential for phase-critical and encoder feedback applications.
Maintenance-Free Service Life
No wear elements, no elastomeric components to degrade, no bolts to retorque. Once correctly installed on aligned shafts, the GT sleeve coupling requires no maintenance throughout its service life.
Compact One-Piece Design
Single cylindrical body — no bolted flanges, no split halves, no external fasteners. Lowest-profile rigid coupling available for co-linear shaft connections, minimising guard size and axial space requirements.
Standard Keyway Compatibility
Bore and keyway dimensions to GB3852-1997 and H7 bore tolerance ensure direct compatibility with standard motor and driven equipment shaft ends throughout the industrial motor range.
Manufacturing Quality
Typical Applications
- Conveyor drive head shaft connections — sustained torque, continuous duty, minimal maintenance
- Compressor motor shaft connections — direct motor to crankshaft coupling with zero torsional play
- Wood processing machinery shaft connections — saw arbor and feed roll rigid drive coupling
- Textile machinery main shaft connections — loom main drive and roller feed rigid coupling
For technical enquiries and volume supply information, visit our contact page.
Customer Reviews and Case Studies
★★★★★
Italy — Industrial Pump OEM
We specify GT6 sleeve couplings for our large centrifugal pump motor connections. The 2,500 N·m rated torque covers our pump range with adequate safety factor, and the rigid connection ensures accurate shaft alignment is maintained between motor and pump bearings.
— Applications Engineer, Milan
★★★★★
Finland — Paper Machine Equipment
Installed on paper machine roll drive connections. The GT6 handles the sustained 2,500 N·m torque at our operating speed and the sleeve coupling’s compact form factor fits within our machine’s tight coupling guard envelope.
— Mechanical Engineer, Helsinki
★★★★☆
Argentina — Mining Equipment
Used on ore conveyor drive shaft connections. The GT6 rigid sleeve coupling has maintained its torque transmission performance through seasonal temperature extremes from -5°C to 40°C at our open-pit mine.
— Equipment Maintenance Engineer, Mendoza
Frequently Asked Questions
What is the advantage of a sleeve coupling over a jaw or spider coupling?
A rigid sleeve coupling transmits torque with absolute zero backlash and no torsional flexibility — ideal for applications where angular fidelity between shafts is required. Jaw or spider couplings introduce torsional compliance, which absorbs shock but introduces angular play. For precision positioning, encoder feedback, and phase-sensitive drives, the rigid sleeve coupling is the correct choice.
Is the GT6 sleeve coupling suitable for direct motor to pump coupling?
Yes. The GT6 with its 2,500 N·m rated torque and 56–80 mm bore range is commonly used for direct motor-to-pump shaft connections on centrifugal pumps in the 75–250 kW power class. Both motor and pump shafts must be accurately aligned — a dial indicator alignment check is recommended before tightening the keys.
What is the rated torque basis for the GT coupling series?
The rated torque Tn is the nominal continuous operating torque the coupling can transmit reliably. It is calculated based on the key-keyway bearing stress limit using the material properties of the sleeve body and shaft material. Peak or intermittent torque should be evaluated against the maximum torque capacity, which is typically 1.5–2.0× the rated torque.
How does the coupling length affect torque capacity?
Longer sleeve length increases the key engagement length, which reduces the bearing stress on the key flanks for a given torque. The GT sleeve series uses proportional length scaling so that each model maintains consistent key bearing stress across its bore range, ensuring the rated torque Tn is achievable for all bore sizes within the model.
What quality checks are performed on GT sleeve couplings during manufacture?
Standard quality checks include dimensional inspection of bore diameter and tolerance, keyway width and depth, OD concentricity with bore, and overall length. Material testing is performed to verify cast iron or steel grade. For special applications, additional checks (ultrasonic testing, hardness verification, dynamic balance) can be requested.
Source the GT6 GT Sleeve Coupling
Ever Power manufactures the GT6 and the complete GT sleeve coupling series — GT1 through GT10, covering 12 mm to 200 mm bore — direct from our factory. Specify bore diameters, keyway requirements, and any non-standard dimensions for a prompt technical and commercial response.