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ASME PALD 7a-1989 — Mechanical Scissors Jacks Safety Standard Addenda (a)
📦 ASME/ANSI PALD-7a-1989 is the first Addenda to the ASME/ANSI PALD-7-1988 Mechanical Scissors Jacks volume. It was approved by ANSI on December 14, 1989, and issued on January 31, 1990. Addenda revise the base edition through replacement pages, with changes marked by the margin note (a). The PALD-7 volume covers mechanical scissors jacks — the “scissors-construction” tire-changing jacks widely supplied with passenger cars, which lift the vehicle by expanding two scissor link sets driven by a threaded screw. This Addenda focuses on the proof load definition, restructuring of the marking paragraphs, and warning/use provisions.
💡 Effect of an Addenda: PALD series revisions become effective three months after the Addenda issue date. Manufacturers, purchasers, and inspectors working with PALD-7-1988 should adopt this Addenda in parallel to keep products and practices compliant with the current requirements.
1. Summary of Changes 📌
| Page | Location | Change |
|---|---|---|
| 1 | Introduction — second paragraph of General | Revised |
| 2 | Section I (Scope) | Revised |
| 5 | Section 2 — definition of “proof load” | Revised |
| 6 | Para. 4.2 (identification) | Revised |
| 6 | Para. 4.3 | Deleted |
| 6 | Former para. 4.4 | Redesignated as 4.3 |
| 7 | Section 6 (product instructions and warnings) | (1) Subparagraph (c) revised; (2) penultimate paragraph revised |
| 8 | Para. 7.1.5 | Added |
⚠️ Watch the renumbering: this Addenda deletes the former para. 4.3 and redesignates the former 4.4 as 4.3. When citing “PALD-7-1988, para. 4.3,” always confirm which version you reference to avoid mixing old and new numbers.
2. Proof Load Definition and Design Testing 🔬
The “proof load” definition is revised in this Addenda, further clarifying its nature as a test load — greater than the rated capacity, applied centrally to the saddle to confirm structural integrity. This matters especially for a scissors jack: its load-carrying ability depends on the strength of the link pivots, the compressive/flexural strength of the screw threads, and the saddle/base structure. The centered and off-center load tests of design qualification (Section 5) exist precisely to verify adequate safety margin in these critical areas above rated capacity.
🚨 The weak links of a scissors jack are usually the link pivots and the screw drive. With the proof load definition revised, the acceptance is stricter: after testing there must be no functional damage — no permanent deformation that causes loss of load or excursions beyond the qualification limits (worn pivots, buckled links, bent screw) — otherwise the product is nonconforming.
3. Marking and Warning Requirements 🏷️
Section 4 was restructured in this Addenda: para. 4.2, as revised, requires identifying mark(s) of the original manufacturer or supplier with the date of manufacture traceable; the former 4.3 was deleted and the former 4.4 redesignated as 4.3. The revised subparagraph (c) and penultimate paragraph of Section 6 complete the elements of the warning label — the word WARNING as a heading, a statement of the hazard, what to do to avoid or reduce it, and a reminder to study and follow all instructions. Typical warnings include “do not overload,” “place the load on the center of the saddle,” and “use on hard, level ground; place the vehicle on support stands after lifting.” The new para. 7.1.5 adds in-service inspection duties.
4. Impact on Manufacturers and Users 📊
- 🔍 Documentation sync: update design and instruction manuals to the current text of “base edition + 7a” and check the renumbering.
- 🔧 Test plans: update design qualification test plans and acceptance criteria to the revised proof load definition.
- 📐 Marking verification: verify that rated capacity, manufacturer identification, and warning labels meet the revised Sections 4 and 6.
- 📋 Inspection updates: incorporate the new para. 7.1.5 into pre-use checks and periodic inspection procedures.
5. Frequently Asked Questions ❓
❓ Q: How does PALD-7a-1989 relate to the 1988 edition?
A: 7a-1989 is the first Addenda to PALD-7-1988. The currently effective text is the 1988 base pages plus this Addenda’s replacement pages; cite the Standard as “including Addenda PALD-7a-1989.”
A: 7a-1989 is the first Addenda to PALD-7-1988. The currently effective text is the 1988 base pages plus this Addenda’s replacement pages; cite the Standard as “including Addenda PALD-7a-1989.”
🔍 Q: What is the difference between a scissors jack (PALD-7) and a screw jack (PALD-5)?
A: Both are mechanical, self-contained emergency tire-changing jacks. The scissors type (PALD-7) lifts by expanding scissor links, has a low initial height and flat stowed profile, and is the mainstream fitment for passenger cars; the threaded-column type (PALD-5) covers vehicles up to 11,000 lb GVW. Choose according to the vehicle manufacturer’s supplied equipment.
A: Both are mechanical, self-contained emergency tire-changing jacks. The scissors type (PALD-7) lifts by expanding scissor links, has a low initial height and flat stowed profile, and is the mainstream fitment for passenger cars; the threaded-column type (PALD-5) covers vehicles up to 11,000 lb GVW. Choose according to the vehicle manufacturer’s supplied equipment.
❓ Q: Why was para. 4.3 deleted and renumbered?
A: The committee consolidated marking requirements and removed duplication, deleting the old 4.3 and redesignating the former 4.4 as 4.3 to keep numbering continuous. Documents citing the old number must be updated.
A: The committee consolidated marking requirements and removed duplication, deleting the old 4.3 and redesignating the former 4.4 as 4.3 to keep numbering continuous. Documents citing the old number must be updated.
❓ Q: When must manufacturers comply with this Addenda?
A: Under the PALD series rules, revisions take effect three months after the Addenda issue date (January 31, 1990, for this one); products manufactured thereafter must meet the current text.
A: Under the PALD series rules, revisions take effect three months after the Addenda issue date (January 31, 1990, for this one); products manufactured thereafter must meet the current text.
