Quick answer: The effective spool radius changes as layers build or disappear. Spring torque must be evaluated together with that radius.
Why can pull force change with cable payout?
At a given torque, cable tension is approximately torque divided by effective radius before friction. A larger radius therefore reduces tension. Record the layer geometry and cable diameter rather than assigning a constant pull from the spring's nominal rating.
A practical verification method
Measure tension at initial, middle and maximum payout and compare with the actual spool build.
| Item | What to record | Purpose |
|---|---|---|
| Reference configuration | Part or assembly identity and drawing revision | Make comparisons traceable |
| Test conditions | Relevant position, direction and operating condition | Compare the same characteristic |
| Decision evidence | Measure tension at initial, middle and maximum payout and compare with the actual spool build. | Resolve the specific question before approval |
Use the result in an engineering request
Describe the observed condition and the required function separately. Include the relevant drawing revision and your results from the check above. If an acceptance limit has not been established, identify it as an open design input rather than treating a successful trial as approval.
Review the related Leading Spring product information. For a project-specific review, send the mechanism description, available geometry and the evidence relevant to this decision through the contact page.
Editorial note: AI-assisted engineering guidance, prepared from the topic-specific reasoning shown here and the company’s public product context. Illustrations explain decisions; they are not customer-case photographs or test results. Product-specific suitability requires review against your approved requirements.