1. Definition and Overview
A Snake Spring Coupling is a flexible power transmission component designed to connect two shafts, accommodating misalignment while damping vibration and shock loads. Its name derives from its unique flexible element: a series of flat, serpentine-shaped springs (the "snake") fitted into the grooves of two aluminum or cast iron hubs.
2. Key Components
Two Hubs: Typically made of lightweight aluminum or high-strength cast iron, each hub attaches to a shaft (the driving and driven shafts). The hubs have curved, lobed grooves on their faces.
Snake Spring Assembly: The core element is a modular spring pack, consisting of multiple flat springs arranged in a serpentine pattern. This assembly is inserted into the grooves of the two hubs.
3. Working Principle
The coupling operates on a simple yet effective principle:
In operation, the torque is transmitted from the driving hub to the spring element.
The spring flexes as it engages and disengages with the lobes of the hubs, transmitting power smoothly to the driven hub.
This flexing action allows the coupling to accommodate angular, parallel, and axial misalignments between the connected shafts.
The spring also acts as a cushion, absorbing vibrations and damping shock loads that occur during operation, protecting both the driving and driven equipment.
4. Key Features and Advantages
Excellent Flexibility and Misalignment Capacity: It can accommodate significant degrees of misalignment, making it ideal for applications where precise shaft alignment is difficult to maintain.
Good Torsional Flexibility: Provides some torsional give, which helps to dampen torsional vibrations and protect systems from resonant frequencies.
High Power Density: Capable of transmitting high torque for its size and weight, especially compared to gear couplings.
Maintenance-Free and Lubrication-Free: Unlike gear couplings, snake spring couplings do not require internal lubrication, reducing maintenance needs and eliminating contamination risks.
Long Service Life: The spring is designed for high-cycle fatigue resistance, ensuring a long operational life under normal conditions.
Simple Installation: The modular design allows for easy assembly and disassembly without needing to move the connected machinery.
5. Potential Disadvantages / Considerations
Limited End-Float Capacity: While good for angular and parallel misalignment, its ability to handle axial movement (end-float) may be less than that of some other coupling types like diaphragm or bellows couplings.
Backlash: There can be a small amount of rotational backlash (free movement between the hubs) due to the clearances necessary for the spring to flex. This may not be suitable for ultra-precise, zero-backlash applications.
Speed Limitation: At very high speeds, centrifugal forces can affect the spring, imposing operational speed limits.
6. Typical Applications
Snake spring couplings are widely used in medium to heavy-duty industrial applications involving variable loads and moderate misalignment, such as:
Marine Propulsion Systems: Connecting ship engines to propellers.
Pumps and Compressors
Generators and Diesel Engines
Mining Equipment
Fans and Blowers
Heavy-Duty Conveyors
