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ASME PALD 4c-1991 — Vehicle Support Stands Safety Standard Addenda (c)
📦 ASME/ANSI PALD-4c-1991 is the third and final Addenda to the ASME/ANSI PALD-4-1987 Vehicle Support Stands volume. It was approved by ANSI on February 14, 1991, and issued on April 22, 1991. Changes are marked by the margin note (c), while (a) and (b) identify the two earlier Addenda. With its revisions to definitions, stability, proof load, and testing paragraphs, this Addenda completes the safety framework for vehicle support stands; the new Appendix A (References) provides users with a bibliography of supporting documents.
💡 This Addenda also compiles the Interpretations of PALD-4-1987 as a separate section for the user’s convenience. That section is not part of the Addenda or of the Standard itself, but it records the Committee’s authoritative readings of the technical provisions.
1. Summary of Changes 📌
| Page | Location | Change |
|---|---|---|
| 5–6 | Paras. 1.1–1.4 Scope/Purpose/Classification/Illustrations | Revised |
| 5 | Section 2 — Definitions | Added: functional damage, manufacturer, repair, supplier |
| 5–6 | Para. 3.6 Stability | Revised (H ≥ 8%V rule) |
| 5–6 | Para. 3.7 Proof load capability | Added (150% of rated capacity) |
| 6 | Para. 4.1 Capacity marking | Title and text revised |
| 6 | Para. 4.2 Identification | Revised |
| 6–7 | Para. 5.1 Proof tests | (1) Revised; (2) paras. 5.1.1 and 5.1.2 mutually redesignated and revised |
| 7 | Section 6 — Product instructions and warnings | Penultimate paragraph revised |
| 8 | Para. 7.1.3(c) | Last paragraph revised |
| 8 | Para. 7.1.4 | Second line corrected by Errata |
| 9 | Appendix A — References | Added |
⚠️ The test paragraphs were swapped: the former 5.1.1 was redesignated 5.1.2, and the former 5.1.2 was redesignated 5.1.1. Always verify that a cited test paragraph belongs to the post-1991 current text, so a test plan does not reference the wrong paragraph.
2. New Definitions and the Stability Rule 🔬
This Addenda adds four key definitions to Section 2: functional damage (any detrimental permanent deformation of the stand’s structure, saddle, or column that results in loss of load or failure to meet the design qualification limits of Section 5), manufacturer (a company that produces goods by hand or machinery, often on a large scale), repair (the process of rehabilitation or replacement of parts that are the same as the original, for the purpose of ensuring performance in accordance with the applicable volume), and supplier (a company that controls the performance specifications and/or design of the products distributed to the general public). These definitions give clear grounds for deciding when a stand must be scrapped and who bears product responsibility.
The stability paragraph 3.6 establishes the quantitative criterion: the minimum horizontal distance from the edge of the saddle to the nearest edge of the projected area of the base shall be at least 8% of the maximum extended vertical height (H ≥ 8%V, with the column moved by hand to remove all slack in the direction of the vertical measurement). Together with the new para. 3.7, stands must be capable of performing the proof load test of para. 5.1.2 with a proof load of 150% of rated capacity applied centrally to the saddle.
🚨 The “8% stability rule plus 150% proof load” is the hard engineering target this Addenda leaves to practice: tall, narrow stands and structures lacking rated-capacity margin are nonconforming. When selecting a stand, check the nameplate rated capacity first, then the ratio of base width to maximum extended height — neither can be skipped.
3. Marking, Testing, and Warnings Completed 🏷️
After the revision of para. 4.1, the rated capacity must be marked prominently on the base by casting imprint, metal stamp, or durable materials and attaching methods; para. 4.2 requires identifying mark(s) of the original manufacturer or supplier, with the manufacturer able to identify the date of manufacture. The revised Section 6 requires a complete warning label (WARNING heading, hazard statement, protective measures, and the reminder to study and follow all instructions). The revised final paragraph of 7.1.3(c) and the errata-corrected second line of 7.1.4 further clarify in-service inspection requirements. With this, vehicle support stands are covered end-to-end — design, testing, marking, and use and maintenance.
4. Impact on Manufacturers and Users 📊
- 🔍 Design conformity: new designs must meet the H ≥ 8%V stability criterion and pass the proof load test at 150% of rated capacity.
- 🔧 Definitions in practice: build a scrapping/repair mechanism on the “functional damage” criterion; supplier and manufacturer responsibilities follow the new definitions.
- 📐 Test documents: check the paragraph-number swap (5.1.1/5.1.2) and update test plans and acceptance criteria.
- 📋 Final text: 4c is the last Addenda; the final consolidated text of the 1987 edition is base pages + (a) + (b) + (c).
5. Frequently Asked Questions ❓
❓ Q: Why is 4c called the “final Addenda”?
A: Under the plan stated in the Foreword, the next full edition of the Standard supersedes the addenda mechanism. 4c is the last Addenda issued for the 1987 edition; no further addenda were published for that edition afterward.
A: Under the plan stated in the Foreword, the next full edition of the Standard supersedes the addenda mechanism. 4c is the last Addenda issued for the 1987 edition; no further addenda were published for that edition afterward.
🔍 Q: Do the Interpretations form part of the Standard?
A: No. The interpretations compiled with PALD-4c are the Committee’s authoritative readings of provisions, issued with the Addenda but separate from both the Addenda and the Standard text. Always cite the paragraph and edition when referencing an interpretation.
A: No. The interpretations compiled with PALD-4c are the Committee’s authoritative readings of provisions, issued with the Addenda but separate from both the Addenda and the Standard text. Always cite the paragraph and edition when referencing an interpretation.
❓ Q: How is V measured in the H ≥ 8%V rule?
A: V is the vertical height at maximum extension (the highest published position). Move the column by hand to remove all slack in the direction of the vertical measurement, then compare the horizontal distance H from the saddle edge to the nearest base edge against 8% of V.
A: V is the vertical height at maximum extension (the highest published position). Move the column by hand to remove all slack in the direction of the vertical measurement, then compare the horizontal distance H from the saddle edge to the nearest base edge against 8% of V.
❓ Q: Can a stand with slight deformation after proof testing remain in service?
A: No. Any functional damage — permanent deformation that causes loss of load or failure to meet qualification limits — requires scrapping; repair must use parts the same as the original, and capability must be re-confirmed after repair.
A: No. Any functional damage — permanent deformation that causes loss of load or failure to meet qualification limits — requires scrapping; repair must use parts the same as the original, and capability must be re-confirmed after repair.
