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ASME PALD 14a-1990 — Scissors Type Mobile Lifts Safety Standard Addenda (a)
✂️ ASME/ANSI PALD-14a-1990 is the first addenda to the Scissors Type Mobile Lifts volume, ASME PALD-14-1989. Approved by ANSI on May 30, 1990 and issued on July 24, 1990, it revises the affected clauses of the 1989 edition through the replacement-page mechanism, with margin notes (a) marking the modified areas. Mirroring PALD-13a-1989, this revision completes the “proof load” definition and clause 3.4 with a tiered requirement (150% vs. 125%) depending on whether an internal load limiting device is fitted, revises the operating controls clause, and adds inspection clause 7.1.5.
💡 Scissors type and swing type mobile lifts are both pneumatic portable lifting devices, and their addenda move in the same direction — unifying proof load practice, reinforcing anti-misoperation controls, and completing inspection programs — showing the coordinated evolution of the PALD series.
1. Principal Changes in This Addenda 📝
Per the Summary of Changes, the modifications in PALD-14a-1990 are:
| Page | Location | Change |
|---|---|---|
| 5 | Section 2 — Definitions | Definition of proof load revised |
| 5 | 3.1 Operating Controls | Revised |
| 6 | 3.4 Proof Load | Revised in its entirety |
| 8 | 7.1.5 | Added |
⚠️ Addenda are issued as replacement pages; retain the addenda title and copyright pages and all replaced pages, and reference clauses from the consolidated text that includes this addenda.
2. Tiered Proof Load Requirements 🔧
The revised 3.4 sets the proof load tier by equipment configuration, anchored on the “load limiting device” concept:
- Lifts without internal load limiting devices: must perform the proof load test of para. 5.1.1 with a proof load of 150% of rated capacity.
- Lifts equipped with internal load limiting devices: must perform the proof load test of para. 5.1.1 with a proof load of 125% of rated capacity.
The logic: a limiting device caps the lift’s actual lifting capability, making a 150% overload physically unattainable; verifying 125% within the device’s envelope covers the limit state. Lifts without such devices must be verified at the 150% margin. Inspectors must apply the multiplier matching the actual configuration.
| Configuration | Proof Load Multiplier | Basis | Purpose |
|---|---|---|---|
| No internal load limiting device | 150% of rated capacity | 3.4(a), 5.1.1 | Full-travel structural integrity verification |
| Internal load limiting device fitted | 125% of rated capacity | 3.4(b), 5.1.1 | Strength verification within the limiting device envelope |
🚨 The proof load tier must match the actual configuration: a claimed limiting device that is missing, or a set point inconsistent with rated capacity, leaves verification inadequate and structural failure possible under overload. Verify the device’s presence, set point, and seal on acceptance.
3. Operating Controls and Other Requirements 🔩
The revised 3.1 makes explicit that control operation must be clear to the operator by position, function, labeling, or a combination thereof, and that the release system requires intentional positive action to prevent accidental lowering. Combined with the 1989 base clauses, the complete safety design of a scissors type mobile lift includes travel limits (3.2), overload capacity (3.3), proof load (3.4), a secondary load holding means (3.5), and saddle restraints with limited lateral adjustment (3.6). The newly added 7.1.5 belongs to the operation, maintenance, and inspection section and must be included in inspection checklists.
4. Engineering Practice Essentials 🛠️
- 🔍 Acceptance verification: confirm the load limiting device configuration matches the proof load multiplier; check test records, set points, and seals.
- 🔧 Operating discipline: use only on hard level surfaces; distribute loads evenly on the saddles in the vehicle manufacturer’s specified areas; transfer to proper supports immediately after lifting.
- 📊 Inspection program: fold revised 7.1.3–7.1.5 into the checklist; regularly inspect pneumatic components, scissors structure, and saddles.
- 📋 Version management: the 1989 edition plus this addenda (a) is the current consolidated text; later addenda continue to stack.
💡 This addenda became effective 3 months after issuance, with prospective application only. Perform acceptance and annual checks against the latest consolidated text and keep revision records for traceability.
From a management standpoint, users should also note the following. First, the scissors pivot points and pneumatic seals are the areas most prone to wear and leakage; periodic inspection should focus on pivot pins, air-line fittings, and seal condition, with immediate removal from service on wear or leakage. Second, maintenance and calibration of the limiting device belong in the equipment file — any adjustment must be performed and recorded by authorized personnel, preventing operators from changing set points. Third, training should combine the standard’s requirements with the manufacturer’s specific operating steps and maintenance intervals to form a complete safety management system. Fourth, because this addenda adds inspection clause 7.1.5, checklists and work instructions should be updated and the new requirement communicated in refresher training. For export or outsourced procurement, cite the current consolidated version (1989 edition plus all addenda) in contracts and require the manufacturer to supply limiting-device set-point documentation and tiered verification test reports, locking in standard conformance at the document level.
5. Frequently Asked Questions ❓
❓ Q: Why is PALD-14a-1990 similar to PALD-13a-1989?
A: Both are first addenda to the scissors and swing type volumes, developed by the same PALD Committee with aligned directions (proof load tiering, operating controls, inspection clauses), reflecting technical coordination across the series.
A: Both are first addenda to the scissors and swing type volumes, developed by the same PALD Committee with aligned directions (proof load tiering, operating controls, inspection clauses), reflecting technical coordination across the series.
❓ Q: How do I choose between the 150% and 125% proof loads?
A: Use 150% for lifts without internal load limiting devices and 125% for lifts with them. The wrong choice either under-verifies the structure or demands an unimplementable test.
A: Use 150% for lifts without internal load limiting devices and 125% for lifts with them. The wrong choice either under-verifies the structure or demands an unimplementable test.
❓ Q: What does the new clause 7.1.5 require?
A: It supplements the operation, maintenance, and inspection section; the exact text governs in the addenda replacement pages. Users should fold it into checklists and training.
A: It supplements the operation, maintenance, and inspection section; the exact text governs in the addenda replacement pages. Users should fold it into checklists and training.
🔍 Q: What should I focus on when accepting a scissors lift?
A: Durable, legible capacity and warning markings; load limiting device configuration matching the proof load tier; complete design qualification test records (especially 5.1.1 and 5.1.3); and complete operator instructions.
A: Durable, legible capacity and warning markings; load limiting device configuration matching the proof load tier; complete design qualification test records (especially 5.1.1 and 5.1.3); and complete operator instructions.
