An elastic coupling is a mechanical device used to connect two rotating shafts (e.g., a motor shaft and a pump shaft) to transmit torque while accommodating for various types of misalignment and absorbing shock loads. The key feature is the inclusion of a flexible, "elastic" element that provides this forgiveness.

Key Characteristics and Purpose

Compensates for Misalignment: Unlike rigid couplings, elastic couplings can handle:

Angular Misalignment: Shafts are at a slight angle to each other.

Parallel Misalignment: Shafts are parallel but offset from one another.

Axial Misalignment: Shafts move slightly towards or away from each other along their axis (end float).

Vibration Damping and Shock Absorption: The elastic element (often made of rubber, polyurethane, or a metallic spring) acts as a damper. It absorbs vibrations from one side (e.g., the motor) and prevents them from being fully transmitted to the other side (e.g., the driven machine). It also softens the impact of sudden torque spikes, protecting both the driver and driven equipment.

Transmits Torque: Its primary function remains the efficient transmission of rotational power from one shaft to another.

Protects Bearings: By reducing vibration and misalignment stresses, elastic couplings extend the life of connected equipment bearings.

Common Types

Jaw Couplings (Spider Couplings): Feature two metal hubs with interlocking "jaws." A spider-shaped elastomeric element (the "spider") fits between the jaws, providing the flexibility. Very common and cost-effective.

Gear Couplings: Use crowned gear teeth that mesh with each other, with flexibility coming from the clearance and the ability of the teeth to slide. They are very robust and can handle high torque.

Beam Couplings (Helical Couplings): Made from a single piece of metal cut in a helical pattern. They are excellent for precision applications (like encoders) and accommodate misalignment through the flexing of the beam.

Tire Couplings: Use a rubber element that resembles a tire, bolted between two hubs. They are excellent for high shock load applications and can accommodate significant misalignment.

Disc Couplings: Use a pack of thin metallic discs that flex to accommodate misalignment. They are precise, maintenance-free, and excellent for high-speed applications.

Advantages

Reduced Maintenance: Protects equipment from wear and tear.

Smoother Operation: Dampens noise and vibration.

Ease of Installation: Tolerates installation inaccuracies better than rigid couplings.

Electrical Insulation: Non-metallic elastic elements can provide insulation between connected shafts.