BIZOMAT MAKEOS · Fasteners
Retaining Ring Thrust Capacity and Groove Edge Margin
What thrust load can this retaining ring and groove carry, and how far from the end must the groove be?
Allowable thrust on a retaining ring application by the handbook formulas: ring shear capacity, the load at the onset of groove yielding for spiral-wound rings, the governing (lower) value, and the minimum distance of the groove from the end of the shaft or bore.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Shaft or housing diameter | mm | Diameter of the shaft or bore carrying the ring. |
| Ring thickness | mm | Thickness of the ring. |
| Groove depth | mm | Depth of the groove. |
| Shear strength of the ring material | MPa | Shear strength of the ring material (from the ring supplier). |
| Yield strength of the groove material | MPa | Compressive yield strength of the grooved part. |
| Shear strength of the groove material | MPa | Shear strength of the grooved part. |
| Safety factor | Safety factor (the handbook notes 3 is usual for ring shear). | |
| Applied thrust load | kN | Axial load the ring must hold. |
| Ring type | choice | Spiral rings contact the whole groove; stamped rings only part of it. |
| Groove contact fraction (stamped) | % | Share of the groove circumference a stamped ring touches. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Shaft or housing diameter
- What it is
- The diameter of the shaft (external ring) or the bore (internal ring) that carries the groove. Both capacities and the groove edge distance are worked out round this circumference.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 25 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Both the ring shear and groove capacities are directly proportional to this diameter.
- Get it right
- Use the shaft or bore diameter, not the groove bottom diameter or the free diameter of the ring.
What this means: Ring thickness
- What it is
- The axial thickness of the ring material, the dimension that is sheared through if the ring itself fails. Take it from the ring supplier’s catalogue.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 50 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The ring shear capacity is directly proportional to the thickness.
- Get it right
- This is the ring’s axial thickness, not its radial section height.
What this means: Groove depth
- What it is
- The radial depth of the groove the ring sits in, from the shaft or bore surface to the groove bottom. It is the shoulder that bears the thrust.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 50 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.5 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The groove yield capacity is directly proportional to the groove depth.
- Get it right
- Groove depth is radial, measured on one side; half the difference between shaft and groove diameters.
What this means: Shear strength of the ring material
- What it is
- The shear strength of the material the ring is made from, which sets the load at which the ring shears through its thickness. Ring suppliers state it for their materials.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 5000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1000 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The ring shear capacity is directly proportional to it.
- Get it right
- Use the ring maker’s figure for the actual ring material and heat treatment, not a generic steel value.
What this means: Yield strength of the groove material
- What it is
- The compressive yield strength of the shaft or housing material in which the groove is cut. The groove wall starts to yield under the ring at this stress.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 5000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 250 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The groove yield capacity is directly proportional to it.
- Get it right
- This belongs to the grooved part, not the ring; soft shafts usually govern.
What this means: Shear strength of the groove material
- What it is
- The shear strength of the grooved part’s material, used to find how far the groove must sit from the end of the shaft or bore so the end does not shear off.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 5000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 200 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher shear strength shortens the minimum groove distance from the end.
- Get it right
- Take it from the material data sheet for the grooved part, not the ring.
What this means: Safety factor
- What it is
- The safety factor that divides both capacities and multiplies the groove edge distance, covering uncertainty in loads and material.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 20. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger factor lowers both capacities and lengthens the minimum groove distance in proportion.
- Get it right
- Choose it from your design standard or the ring supplier’s guidance; the guide notes the handbook’s usual figure for ring shear.
What this means: Applied thrust load
- What it is
- The axial thrust the ring must hold in service, compared with the allowable thrust and used to size the groove distance from the end.
- Units and format
- Enter a number in kN: kilonewtons (1 kN = 1000 N). The form accepts 0 kN to 100000 kN. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 kN as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The minimum groove distance from the end rises in proportion to the load.
- Get it right
- Include shock or impact loads in this figure; the method is for static thrust.
What this means: Ring type
- What it is
- The kind of ring: a spiral-wound ring bears on the whole groove circumference, a stamped ring touches only part of it, which lowers the groove capacity.
- Units and format
- Choose one of 2 options from the list: Spiral-wound (full contact); Stamped (partial contact).
- Example
- The form opens with “Spiral-wound (full contact)” selected as a worked example. Choose the option that matches your case.
- Get it right
- Choose stamped for ordinary circlips with lugs or gaps; then set the contact fraction.
What this means: Groove contact fraction (stamped)
- What it is
- The share of the groove circumference that a stamped ring actually touches. It scales the groove yield capacity; it is ignored for spiral-wound rings.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 70% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The groove yield capacity is directly proportional to this share.
- Get it right
- Use the ring maker’s data for the actual ring; it is not used when the ring type is spiral-wound.
Method and formulas
- Ring shear: P_s = π D t S_s ÷ K.
- Groove yield onset: P_G = π D d S_y ÷ K (× contact fraction for stamped rings).
- Allowable thrust = the lower of the two; minimum groove distance from the end Y = K P ÷ (π D S_c).
- Example: a 25 mm shaft with a 0.5 mm groove in 250 MPa steel allows 3.2725 kN.
Limitations
- Static thrust with square groove corners and line-to-line contact; chamfers and corner radii on the retained part reduce capacity.
- Use the ring supplier’s ratings for final selection.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a circlip or spiral ring against an axial load
- Choose groove material and depth for a higher thrust
- Locate a groove safely near a shaft end
Who it is for
- Design engineers
- Maintenance engineers
- Assembly engineers
What you get
- Ring shear capacity
- Groove yield capacity
- Minimum groove distance from the end
Interpreting the result
- Groove yield usually governs; a harder groove material or a deeper groove raises capacity.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1763–1789. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · Library collection
Retaining rings and circlips: choosing types, designing grooves and installing them so they stay put
In Machine Elements and Mechanical Design
What it covers: How internal and external circlips, E-clips, spiral rings and push-on rings locate parts on shafts and in bores, how grooves and abutting parts set their capacity, and how to avoid common failures.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Retaining Ring Thrust Capacity and Groove Edge Margin calculator