Shim Pack Couplings

Shim pack coupling is a high-performance flexible coupling that compensates for the relative displacement between two connected shafts through the elastic deformation of one or more sets of metal diaphragms. Shim pack couplings with their unique performance advantages, have been widely used in industrial fields such as aviation, shipbuilding, power, and petrochemicals.

Compared with traditional gear couplings or rubber elastic couplings, shim pack couplings have significant characteristics such as no wear, no maintenance, and high reliability. The core component is a thin-walled diaphragm group made of high-strength stainless steel, which can adapt to axial, radial, and angular deviations while transmitting torque through precise pre tensioning installation.

A typical shim pack coupling consists of the following main components:

• Wheel hub components: usually made of high-strength alloy steel, directly connected to the drive shaft and the driven shaft
  

• Diaphragm group: an elastic element composed of multiple stainless steel sheets, which is the core component of a coupling
  

• Intermediate shaft: Some models are designed with an intermediate shaft to increase compensation capability
  

• Connecting bolts: high-precision fasteners to ensure reliable connection of various components

According to different structural forms, membranes are mainly divided into:

• Single piece diaphragm: simple structure, suitable for small torque transmission
  

• Multi piece membrane: Improving load-bearing capacity and compensation capability through multi-layer stacking
  

• Corrugated membrane: special corrugated design enhances elastic deformation ability
  

• Fan shaped membrane: segmented design reduces stress concentration

Shim pack couplings compensate for shaft system deviations through the elastic deformation of metal diaphragms:

• Torque transmission: transmitting power through the shear action of the diaphragm group
  

• Deviation compensation: Diaphragm deformation absorbs axial, radial, and angular displacements
  

• Vibration damping: The elasticity of the diaphragm can partially absorb and isolate vibrations

Main performance characteristics

• High torque transmission capability: large torque transmission per unit weight
  

• Zero backlash: ensuring transmission accuracy, suitable for precision transmission
  

• Maintenance free: No worn parts, long service life
  

• High speed adaptability: excellent dynamic balance performance
  

• Corrosion resistance: Stainless steel diaphragm is suitable for harsh environments
  

• Wide temperature adaptability: the working temperature range can reach -50 ℃ to 300 ℃

Types of shim pack couplings

• Classified by structure
  Single membrane type: simple structure, limited compensation capability
  Double membrane type: enhances angular and radial compensation capability
  Multi membrane type: used for high-power and high-precision applications
  Type with intermediate shaft: suitable for long-distance transmission

• Classified by connection method
  Flange connection type
  Clamping type
  Keyway connection type
  Spline connection type

Key parameters

• Rated torque: the maximum torque that the coupling can continuously operate at
  

• Maximum torque: the peak torque that can be sustained in the short term
  

• Speed range: allowable working speed range
  

• Deviation compensation capability:
  Axial displacement: usually 0.2-5mm
  Radial displacement: usually 0.1-3mm
  Angular displacement: usually 0.5 ° -3 °

Selection considerations

• Power and torque requirements of the transmission system
  

• Possible types and sizes of deviations in the shaft system
  

• Working environment conditions (temperature, corrosiveness, etc.)
  

• Installation space restrictions
  

• Dynamic performance requirements (such as critical speed)

Installation precautions

• Ensure that the shaft end is clean and free of burrs
  

• Using the correct method for centering (laser centering is recommended)
  

• Install bolts according to the prescribed tightening torque
  

• To avoid pre deformation of the membrane caused by forced assembly

Although shim pack couplings are generally maintenance free, regular inspections are still necessary

• Check the tightening status of bolts
  

• Observe the membrane for cracks or deformation
  

• Monitor changes in vibration conditions
  

• Check the status of the seals (if any)

Shim couplings are widely used in:

• Energy industry: Steam turbines, generators, compressors
  

• Shipbuilding industry: propulsion systems, auxiliary machinery
  

• Petrochemical industry: pump sets, fans, compressors
  

• Aerospace: Engine Accessories Transmission
  

• Precision machinery: CNC machine tools, measuring equipment

As an important component of modern mechanical transmission systems, shim pack couplings will continue to drive industrial equipment towards high efficiency, reliability, and intelligence through their technological development. With the application of new materials and processes, the performance boundary of shim couplings will continue to expand to meet more demanding industrial application requirements.