Tips on Comparing Different Types of Collars and Couplings
Additional Information on Material Content and Finishes
Material content
- Steel is mild low carbon to ASTM A 283 GrC or equivalent, which can be machined, welded, and case hardened.
- Stainless steel is 18-8 series, passivated.
- Aluminum is aircraft Grade 2024A or equivalent, which has high strength, excellent fatigue resistance, and a bright finish.
Finishes
- Standard finishes on steel collars are RoHS-compliant bright zinc and clear chromate or black oxide and oil.
- Custom finishes such as chrome, nickel, zinc, and yellow dichromate are also available on steel split collars and couplings.
Note: Plated shaft collars and couplings come with unplated screws. This is to protect against hydrogen embrittlement, which causes failures when hardened socket cap screws are plated.
Shaft Collars Comparison Chart
| Type | Key Advantage | Characteristics | Available Materials and Finish |
| Set | Most economical shaft collar |
Install on the shaft by tightening a set screw that extends through the shaft collar. Unfortunately, the screw often mars the shaft.
|
Inch – steel, zinc plated, black oxide, plain and bright finish. Stainless steel Metric – steel, black oxide. Stainless steel |
| Single split | Doesn’t mar the shaft and provides a much greater axial load than set screw collars. |
Used when the end of the shaft is accessible, and collars can be slid into position. Functions as a clamp around the circumference of the shaft. Held in place by one socket head cap screw. Diameters up to 1-1/2 inches (35mm) have a relief cut, which allows the smaller screws used in those diameters to provide maximum clamping load.
|
Inch – steel, black oxide, bright finish stainless steel, and aluminum Metric – steel, black oxide, and bright finish stainless steel |
| Double split | Loaded values exceed that of a single split collar by about 10%. |
Used for mid-shaft applications when components such as bearings, sprockets, or sheaves are already in place, or when a slightly greater axial load is desired. Can compensate for a slightly undersized or oversized shaft. Held in place by two socket head cap screws. |
Inch -steel, black oxide, and bright finish stainless steel, aluminum Metric – steel, black oxide, and bright finish stainless steel |
| Heavy split | Slightly larger outer diameter than standard split collars | Comes as single and double split. Have recessed screw heads. |
Inch -steel black oxide and bright finish stainless steel
|
| Threaded | Split collars are used on threaded shafts. | Available in USS (coarse) and SAE (fine) thread. Single and double split styles. |
Inch - Single – steel black oxide, bright finish stainless steel Inch - Double – steel, black oxide |
Shaft Couplings Comparison Chart
| Type | Key Advantage | Characteristics | Available Materials and Finish |
| Rigid | Most economical. Comes with or without keyways. Held by two set screws. |
Installed by a set screw that extends through the shaft collar. Unfortunately, that screw often mars the shaft. |
Inch – steel, black oxide |
| Single split | Comes with or without keyways. |
Come with straight and stepped bores (inch only) for joining different diameter shafts. Clamp with four cap screws. Stepped bores are available in inch without a keyway. |
Inch – steel, black oxide, and bright finish stainless steel Metric – steel, black oxide, and bright finish stainless steel |
| Double split | Comes with or without keyways. |
Come with straight and stepped bores (inch only) for joining different diameter shafts. Develop a greater load than a single split shaft coupling, due to the eight-socket cap screws vs. the four used in a single split. Double split with keyway provides the greatest load available in a coupling application. Stepped bores are available with and without keyways in inch. |
Inch - steel, black oxide, and bright finish stainless steel. Aluminum Metric – steel, black oxide. and bright finish stainless steel |
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