sleeve coupling

A sleeve coupling is a mechanical device used to connect two shafts together end-to-end to transmit torque (rotary power). It is the simplest type of rigid coupling, meaning it does not accommodate for misalignment between shafts and requires precise installation for optimal performance.
🛠️ Structure and Design
A traditional rigid sleeve coupling is essentially a hollow cylinder, often made of cast iron.
• Sleeve (or Muff): A hollow pipe or cylinder with an inner diameter that matches the outer diameter of the shafts being connected.
• Shafts: The driving and driven shafts are inserted into each end of the sleeve and abut against each other.
• Key and Keyway: A key (often a gib head sunk key) is fitted into keyways in both the shafts and the inner bore of the sleeve. This prevents the shafts and sleeve from slipping relative to one another and ensures power transmission occurs through the key.
• Securing Mechanisms: Threaded holes are sometimes provided in the sleeve so that set screws or bolts can lock the coupling in position, preventing axial (longitudinal) movement.
⚙️ Function and Operation
Sleeve couplings are used where precise shaft alignment is required and the load capacity is light to medium duty.
• Power Transmission: The primary function is to transmit power from the driving shaft to the driven shaft.
• Rigidity: Because they are rigid, any misalignment will put stress on the coupling and connected machinery, which is why precise alignment during installation is crucial.
• Simplicity: Power transmission is straightforward, with no power loss due to friction or flexing components.
💡 Variations
While the basic design is rigid, variations exist for specific applications:
• Split Muff Coupling: The sleeve is split into two semi-cylindrical halves that are bolted together around the shafts. This design allows for easier assembly and disassembly without needing to move the connected machinery.
• Flexible Sleeve Couplings: Other types of "sleeve couplings" might refer to flexible variations that use a synthetic or nylon sleeve insert between two hubs to accommodate minor misalignments, absorb shocks, and reduce vibration.
• Pipe Repair Sleeves: In plumbing or HVAC, "sleeve couplings" can refer to devices used to connect or repair pipes of varying materials and diameters, often using gaskets for a leak-proof seal.