ブログ について Key Principles for Selecting Power Transmission Couplings

Simply put, a coupling is a mechanical device that connects two shafts to transmit power or torque from one to another. Think of it as a bridge linking power sources to actuating mechanisms while ensuring efficient energy transfer.

One might wonder why shafts can't be directly connected. The answer lies in practical applications where shaft alignment often contains imperfections, and operational conditions cause displacements. Direct connections would subject shafts to additional stress and potential damage. Couplings compensate for these misalignments, protect equipment, and maintain smooth power transmission.

Additionally, couplings serve these critical functions:

• Power transmission: Their fundamental role is transferring power from driving to driven shafts.
• Connecting independent components: Linking separately manufactured parts like motor output shafts and generators.
• Providing flexibility: Offering adaptable power transmission in space-constrained environments.
• Overload protection: Safeguarding equipment against damage during excessive loads.
• Dampening shock loads: Flexible couplings reduce impact transfer between shafts.

Couplings come in numerous varieties based on operating principles and structural characteristics. Below we examine common types and their uses:

The simplest coupling type consists of a hollow cylinder (sleeve) whose inner diameter matches the shafts' outer diameters. Both shaft ends insert into opposite sleeve openings, secured via bolts or keys. While inexpensive and straightforward, sleeve couplings cannot compensate for misalignment, making them suitable for well-aligned applications.

Structural features:

• Single cylindrical sleeve construction
• Sleeve inner diameter matches shaft dimensions
• Bolted or keyed fastening

Applications:

• Precision-aligned systems
• Light-to-medium load scenarios
• Basic drive systems with moderate accuracy requirements

Similar to sleeve couplings but featuring a longitudinally split sleeve design. This configuration enables easier installation/removal without shaft displacement. Typically employed for medium-load and moderate-speed applications.

Structural features:

• Two-part sleeve for simplified maintenance
• Bolt-fastened assembly

Applications:

• Frequent maintenance equipment
• Medium-load operations

Comprising two flanged half-couplings (each fixed to a shaft) joined by bolts. This robust design handles medium-to-heavy loads effectively.

Structural features:

• Dual flanged components
• Bolted connection
• Keyway slots for enhanced strength

Applications:

• Heavy-duty torque transmission
• Pumps, compressors, large motors

A common flexible coupling using rubber-bushed pins to connect half-couplings. The elastomeric elements absorb vibrations/shocks while accommodating minor misalignments.

Structural features:

• Rubber-bushed pin connections
• Axial/radial/angular misalignment tolerance

Applications:

• Slightly misaligned systems
• Moderate-load applications
• Motor-reducer-pump combinations

Featuring two external-gear half-couplings mated with an internal-gear sleeve. This high-torque design suits heavy-load, low-speed applications but requires precise alignment and generates operational noise.

Structural features:

• Gear-to-gear power transmission
• Exceptional load capacity

Applications:

• Rolling mills, cranes
• Heavy machinery

Utilizing hydraulic fluid for power transfer between pump (drive shaft) and turbine (driven shaft) impellers. Provides smooth starts and overload protection.

Structural features:

• Hydraulic power transmission
• Pump-turbine assembly
• Vibration damping

Applications:

• Mining equipment
• Conveyor systems
• Marine propulsion

Accommodates substantial angular misalignment via crossed-yoke and spider assembly. Widely used in automotive and construction equipment drivetrains.

Structural features:

• Cross-shaped pivot mechanism
• High angular flexibility

Applications:

• Vehicle transmission systems
• Connecting gearboxes to axles

A specialized universal joint maintaining constant output/input speed ratios despite angular displacement. Critical for front-wheel drive vehicle stability.

Structural features:

• Precision speed synchronization
• Complex manufacturing

Applications:

• Front-wheel drive axles
• Vibration-free vehicle operation

As standardized machine elements, couplings require proper selection, installation, and periodic inspection per application needs. Operators should monitor for abnormal noises/vibrations indicating premature failure. Regular wear and fatigue assessments prolong service life.

Couplings serve as indispensable components in power transmission systems, with diverse types catering to varied industrial needs. Appropriate coupling selection ensures reliable equipment operation and longevity. This overview provides foundational knowledge for making informed coupling choices in practical applications.